1: # Setting up TCP/IP on NetBSD in practice
2:
3: ## A walk through the kernel configuration
4:
5: Before we dive into configuring various aspects of network setup, we want to
6: walk through the necessary bits that have to or can be present in the kernel.
7: See [[Compiling the kernel|guide/kernel]] for more details on compiling the
8: kernel, we will concentrate on the configuration of the kernel here. We will
9: take the i386/GENERIC config file as an example here. Config files for other
10: platforms should contain similar information, the comments in the config files
11: give additional hints. Besides the information given here, each kernel option is
12: also documented in the
13: [options(4)](http://netbsd.gw.com/cgi-bin/man-cgi?options+4+NetBSD-5.0.1+i386)
14: manpage, and there is usually a manpage for each driver too, e.g.
15: [tlp(4)](http://netbsd.gw.com/cgi-bin/man-cgi?tlp+4+NetBSD-5.0.1+i386).
16:
17: The first line of each config file shows the version. It can be used to compare
18: against other versions via CVS, or when reporting bugs.
19:
20: options NTP # NTP phase/frequency locked loop
21:
22: If you want to run the Network Time Protocol (NTP), this option can be enabled
23: for maximum precision. If the option is not present, NTP will still work. See
24: [ntpd(8)](http://netbsd.gw.com/cgi-bin/man-cgi?ntpd+8+NetBSD-5.0.1+i386) for
25: more information.
26:
27: file-system NFS # Network File System client
28:
29: If you want to use another machine's hard disk via the Network File System
30: (NFS), this option is needed. The guide article about the
31: [[Network File System|guide/net-services#nfs]] gives more information on NFS.
32:
33: options NFSSERVER # Network File System server
34:
35: This option includes the server side of the NFS remote file sharing protocol.
36: Enable if you want to allow other machines to use your hard disk. The mentioned
37: article in the guide about [[NFS|guide/net-services#nfs]] contains more
38: information on NFS.
39:
40: #options GATEWAY # packet forwarding
41:
42: If you want to setup a router that forwards packets between networks or network
43: interfaces, setting this option is needed. It doesn't only switch on packet
44: forwarding, but also increases some buffers. See
45: [options(4)](http://netbsd.gw.com/cgi-bin/man-cgi?options+4+NetBSD-5.0.1+i386)
46: for details.
47:
48: options INET # IP + ICMP + TCP + UDP
49:
50: This enables the TCP/IP code in the kernel. Even if you don't want/use
51: networking, you will still need this for machine-internal communication of
52: subsystems like the X Window System. See
53: [inet(4)](http://netbsd.gw.com/cgi-bin/man-cgi?inet+4+NetBSD-5.0.1+i386) for
54: more details.
55:
56: options INET6 # IPV6
57:
58: If you want to use IPv6, this is your option. If you don't want IPv6, which is
59: part of NetBSD since the 1.5 release, you can remove/comment out that option.
60: See the
61: [inet6(4)](http://netbsd.gw.com/cgi-bin/man-cgi?inet6+4+NetBSD-5.0.1+i386)
62: manpage and [[Next generation Internet protocol -
63: IPv6|guide/net-intro#ipv6-intro]] for more information on the next generation
64: Internet protocol.
65:
66: #options IPSEC # IP security
67:
68: Includes support for the IPsec protocol, including key and policy management,
69: authentication and compression. This option can be used without the previous
70: option INET6, if you just want to use IPsec with IPv4, which is possible. See
71: [ipsec(4)](http://netbsd.gw.com/cgi-bin/man-cgi?ipsec+4+NetBSD-5.0.1+i386) for
72: more information.
73:
74: #options IPSEC_ESP # IP security (encryption part; define w/IPSEC)
75:
76: This option is needed in addition to IPSEC if encryption is wanted in IPsec.
77:
78: #options MROUTING # IP multicast routing
79:
80: If multicast services like the MBone services should be routed, this option
81: needs to be included. Note that the routing itself is controlled by the
82: [mrouted(8)](http://netbsd.gw.com/cgi-bin/man-cgi?mrouted+8+NetBSD-5.0.1+i386)
83: daemon.
84:
85: options ISO,TPIP # OSI
86: #options EON # OSI tunneling over IP
87:
88: These options include the OSI protocol stack, which was said for a long time to
89: be the future of networking. It's mostly history these days. :-) See the
90: [iso(4)](http://netbsd.gw.com/cgi-bin/man-cgi?iso+4+NetBSD-5.0.1+i386) manpage
91: for more information.
92:
93: options NETATALK # AppleTalk networking protocols
94:
95: Include support for the AppleTalk protocol stack. Userland server programs are
96: needed to make use of that. See pkgsrc/net/netatalk and pkgsrc/net/netatalk-asun
97: for such packages. More information on the AppleTalk protocol and protocol stack
98: are available in the
99: [atalk(4)](http://netbsd.gw.com/cgi-bin/man-cgi?atalk+4+NetBSD-5.0.1+i386)
100: manpage.
101:
102: options PPP_BSDCOMP # BSD-Compress compression support for PPP
103: options PPP_DEFLATE # Deflate compression support for PPP
104: options PPP_FILTER # Active filter support for PPP (requires bpf)
105:
106: These options tune various aspects of the Point-to-Point protocol. The first two
107: determine the compression algorithms used and available, while the third one
108: enables code to filter some packets.
109:
110: options PFIL_HOOKS # pfil(9) packet filter hooks
111: options IPFILTER_LOG # ipmon(8) log support
112:
113: These options enable firewalling in NetBSD, using IPFilter. See the
114: [ipf(4)](http://netbsd.gw.com/cgi-bin/man-cgi?ipf+4+NetBSD-5.0.1+i386) and
115: [ipf(8)](http://netbsd.gw.com/cgi-bin/man-cgi?ipf+8+NetBSD-5.0.1+i386) manpages
116: for more information on operation of IPFilter, and [[Configuring the
117: gateway/firewall|guide/net-practice#ipnat-configuring-gateway]] for a
118: configuration example.
119:
120: # Compatibility with 4.2BSD implementation of TCP/IP. Not recommended.
121: #options TCP_COMPAT_42
122:
123: This option is only needed if you have machines on the network that still run
124: 4.2BSD or a network stack derived from it. If you've got one or more
125: 4.2BSD-systems on your network, you've to pay attention to set the right
126: broadcast-address, as 4.2BSD has a bug in its networking code, concerning the
127: broadcast address. This bug forces you to set all host-bits in the
128: broadcast-address to `0`. The `TCP_COMPAT_42` option helps you ensuring this.
129:
130: options NFS_BOOT_DHCP,NFS_BOOT_BOOTPARAM
131:
132: These options enable lookup of data via DHCP or the BOOTPARAM protocol if the
133: kernel is told to use a NFS root file system. See the
134: [diskless(8)](http://netbsd.gw.com/cgi-bin/man-cgi?diskless+8+NetBSD-5.0.1+i386)
135: manpage for more information.
136:
137: # Kernel root file system and dump configuration.
138: config netbsd root on ? type ?
139: #config netbsd root on sd0a type ffs
140: #config netbsd root on ? type nfs
141:
142: These lines tell where the kernel looks for its root file system, and which
143: filesystem type it is expected to have. If you want to make a kernel that uses a
144: NFS root filesystem via the tlp0 interface, you can do this with
145:
146: root on tlp0 type nfs
147:
148: If a `?` is used instead of a device/type, the kernel tries to
149: figure one out on its own.
150:
151: # ISA serial interfaces
152: com0 at isa? port 0x3f8 irq 4 # Standard PC serial ports
153: com1 at isa? port 0x2f8 irq 3
154: com2 at isa? port 0x3e8 irq 5
155:
156: If you want to use PPP or SLIP, you will need some serial (com) interfaces.
157: Others with attachment on USB, PCMCIA or PUC will do as well.
158:
159: # Network Interfaces
160:
161: This rather long list contains all sorts of network drivers. Please pick the one
162: that matches your hardware, according to the comments. For most drivers, there's
163: also a manual page available, e.g.
164: [tlp(4)](http://netbsd.gw.com/cgi-bin/man-cgi?tlp+4+NetBSD-5.0.1+i386),
165: [ne(4)](http://netbsd.gw.com/cgi-bin/man-cgi?ne+4+NetBSD-5.0.1+i386), etc.
166:
167: # MII/PHY support
168:
169: This section lists media independent interfaces for network cards. Pick one that
170: matches your hardware. If in doubt, enable them all and see what the kernel
171: picks. See the
172: [mii(4)](http://netbsd.gw.com/cgi-bin/man-cgi?mii+4+NetBSD-5.0.1+i386) manpage
173: for more information.
174:
175: # USB Ethernet adapters
176: aue* at uhub? port ? # ADMtek AN986 Pegasus based adapters
177: cue* at uhub? port ? # CATC USB-EL1201A based adapters
178: kue* at uhub? port ? # Kawasaki LSI KL5KUSB101B based adapters
179:
180: USB-ethernet adapters only have about 2MBit/s bandwidth, but they are very
181: convenient to use. Of course this needs other USB related options which we won't
182: cover here, as well as the necessary hardware. See the corresponding manpages
183: for more information.
184:
185: # network pseudo-devices
186: pseudo-device bpfilter 8 # Berkeley packet filter
187:
188: This pseudo-device allows sniffing packets of all sorts. It's needed for
189: tcpdump, but also rarpd and some other applications that need to know about
190: network traffic. See
191: [bpf(4)](http://netbsd.gw.com/cgi-bin/man-cgi?bpf+4+NetBSD-5.0.1+i386) for more
192: information.
193:
194: pseudo-device ipfilter # IP filter (firewall) and NAT
195:
196: This one enables the IPFilter's packet filtering kernel interface used for
197: firewalling, NAT (IP Masquerading) etc. See
198: [ipf(4)](http://netbsd.gw.com/cgi-bin/man-cgi?ipf+4+NetBSD-5.0.1+i386) and
199: [Configuring the gateway/firewall|guide/net-practice#ipnat-configuring-gateway]]
200: for more information.
201:
202: pseudo-device loop # network loopback
203:
204: This is the `lo0` software loopback network device which is used by some
205: programs these days, as well as for routing things. It should not be omitted.
206: See [lo(4)](http://netbsd.gw.com/cgi-bin/man-cgi?lo+4+NetBSD-5.0.1+i386) for
207: more details.
208:
209: pseudo-device ppp 2 # Point-to-Point Protocol
210:
211: If you want to use PPP either over a serial interface or ethernet (PPPoE), you
212: will need this option. See
213: [ppp(4)](http://netbsd.gw.com/cgi-bin/man-cgi?ppp+4+NetBSD-5.0.1+i386) for
214: details on this interface.
215:
216: pseudo-device sl 2 # Serial Line IP
217:
218: Serial Line IP is a simple encapsulation for IP over (well :) serial lines. It
219: does not include negotiation of IP addresses and other options, which is the
220: reason that it's not in widespread use today any more. See
221: [sl(4)](http://netbsd.gw.com/cgi-bin/man-cgi?sl+4+NetBSD-5.0.1+i386).
222:
223: pseudo-device strip 2 # Starmode Radio IP (Metricom)
224:
225: If you happen to have one of the old Metricom Ricochet packet radio wireless
226: network devices, use this pseudo-device to use it. See the
227: [strip(4)](http://netbsd.gw.com/cgi-bin/man-cgi?strip+4+NetBSD-5.0.1+i386)
228: manpage for detailed information.
229:
230: pseudo-device tun 2 # network tunneling over tty
231:
232: This network device can be used to tunnel network packets to a device file,
233: `/dev/tun*`. Packets routed to the tun0 interface can be read from `/dev/tun0`,
234: and data written to `/dev/tun0` will be sent out the tun0 network interface.
235: This can be used to implement e.g. QoS routing in userland. See
236: [tun(4)](http://netbsd.gw.com/cgi-bin/man-cgi?tun+4+NetBSD-5.0.1+i386) for
237: details.
238:
239: pseudo-device gre 2 # generic L3 over IP tunnel
240:
241: The GRE encapsulation can be used to tunnel arbitrary layer 3 packets over IP,
242: e.g. to implement VPNs. See
243: [gre(4)](http://netbsd.gw.com/cgi-bin/man-cgi?gre+4+NetBSD-5.0.1+i386) for more.
244:
245: pseudo-device gif 4 # IPv[46] over IPv[46] tunnel (RFC 1933)
246:
247: Using the GIF interface allows to tunnel e.g. IPv6 over IPv4, which can be used
248: to get IPv6 connectivity if no IPv6-capable uplink (ISP) is available. Other
249: mixes of operations are possible, too. See the
250: [gif(4)](http://netbsd.gw.com/cgi-bin/man-cgi?gif+4+NetBSD-5.0.1+i386) manpage
251: for some examples.
252:
253: #pseudo-device faith 1 # IPv[46] tcp relay translation i/f
254:
255: The faith interface captures IPv6 TCP traffic, for implementing userland
256: IPv6-to-IPv4 TCP relays e.g. for protocol transitions. See the
257: [faith(4)](http://netbsd.gw.com/cgi-bin/man-cgi?faith+4+NetBSD-5.0.1+i386)
258: manpage for more details on this device.
259:
260: #pseudo-device stf 1 # 6to4 IPv6 over IPv4 encapsulation
261:
262: This adds a network device that can be used to tunnel IPv6 over IPv4 without
263: setting up a configured tunnel before. The source address of outgoing packets
264: contains the IPv4 address, which allows routing replies back via IPv4. See the
265: [stf(4)](http://netbsd.gw.com/cgi-bin/man-cgi?stf+4+NetBSD-5.0.1+i386) manpage
266: and [IPv6 Connectivity & Transition via 6to4|guide/net-practice#ipv6-6to4]] for
267: more details.
268:
269: pseudo-device vlan # IEEE 802.1q encapsulation
270:
271: This interface provides support for IEEE 802.1Q Virtual LANs, which allows
272: tagging Ethernet frames with a `vlan` ID. Using properly configured switches
273: (that also have to support VLAN, of course), this can be used to build virtual
274: LANs where one set of machines doesn't see traffic from the other (broadcast and
275: other). The
276: [vlan(4)](http://netbsd.gw.com/cgi-bin/man-cgi?vlan+4+NetBSD-5.0.1+i386) manpage
277: tells more about this.
278:
279: ## Overview of the network configuration files
280:
281: The following is a list of the files used to configure the network. The usage of
282: these files, some of which have already been met the first chapters, will be
283: described in the following sections.
284:
285: * `/etc/hosts` -- Local hosts database file. Each line contains information
286: regarding a known host and contains the internet address, the host's name and
287: the aliases. Small networks can be configured using only the hosts file,
288: without a *name server*.
289:
290: * `/etc/resolv.conf` -- This file specifies how the routines which provide
291: access to the Internet Domain Name System should operate. Generally it
292: contains the addresses of the name servers.
293:
294: * `/etc/ifconfig.xxx` -- This file is used for the automatic configuration of
295: the network card at boot.
296:
297: * `/etc/mygate` -- Contains the IP address of the gateway.
298:
299: * `/etc/nsswitch.conf` -- Name service switch configuration file. It controls
300: how a process looks up various databases containing information regarding
301: hosts, users, groups, etc. Specifically, this file defines the order to look
302: up the databases. For example, the line:
303:
304: hosts: files dns
305:
306: specifies that the hosts database comes from two sources, *files* (the local
307: `/etc/hosts` file) and *DNS*, (the Internet Domain Name System) and that the
308: local files are searched before the DNS.
309:
310: It is usually not necessary to modify this file.
311:
312: ## Connecting to the Internet with a modem
313:
314: There are many types of Internet connections: this section explains how to
315: connect to a provider using a modem over a telephone line using the PPP
316: protocol, a very common setup. In order to have a working connection, the
317: following steps must be done:
318:
319: 1. Get the necessary information from the provider.
320: 2. Edit the file `/etc/resolv.conf` and check `/etc/nsswitch.conf`.
321: 3. Create the directories `/etc/ppp` and `/etc/ppp/peers` if they don't exist.
322: 4. Create the connection script, the chat file and the pppd options file.
323: 5. Created the user-password authentication file.
324:
325: Judging from the previous list it looks like a complicated procedure that
326: requires a lot of work. Actually, the single steps are very easy: it's just a
327: matter of modifying, creating or simply checking some small text files. In the
328: following example it will be assumed that the modem is connected to the second
329: serial port `/dev/tty01` (COM2 in DOS).
330:
331: A few words on the difference between `com`, `COM` and `tty`. For NetBSD, `com`
332: is the name of the serial port driver (the one that is displayed by `dmesg`) and
333: `tty` is the name of the port. Since numbering starts at 0, `com0` is the driver
334: for the first serial port, named `tty00`. In the DOS world, instead, `COM1`
335: refers to the first serial port (usually located at 0x3f8), `COM2` to the
336: second, and so on. Therefore `COM1` (DOS) corresponds to `/dev/tty00` (NetBSD).
337:
338: Besides external modems connected to COM ports (using `/dev/tty0[012]` on i386,
339: `/dev/tty[ab]` on sparc, ...) modems on USB (`/dev/ttyU*`) and pcmcia/cardbus
340: (`/dev/tty0[012]`) can be used.
341:
342: ### Getting the connection information
343:
344: The first thing to do is ask the provider the necessary information for the
345: connection, which means:
346:
347: * The phone number of the nearest POP.
348: * The authentication method to be used.
349: * The username and password for the connection.
350: * The IP addresses of the name servers.
351:
352: ### resolv.conf and nsswitch.conf
353:
354: The `/etc/resolv.conf` file must be configured using the information supplied by
355: the provider, especially the addresses of the DNS. In this example the two DNS
356: will be `194.109.123.2` and `191.200.4.52`:
357:
358: nameserver 194.109.123.2
359: nameserver 191.200.4.52
360:
361: And now an example of the `/etc/nsswitch.conf` file:
362:
363: # /etc/nsswitch.conf
364: group: compat
365: group_compat: nis
366: hosts: files dns
367: netgroup: files [notfound=return] nis
368: networks: files
369: passwd: compat
370: passwd_compat: nis
371: shells: files
372:
373: The defaults of doing hostname lookups via `/etc/hosts` followed by the DNS
374: works fine and there's usually no need to modify this.
375:
376: ### Creating the directories for pppd
377:
378: The directories `/etc/ppp` and `/etc/ppp/peers` will contain the configuration
379: files for the PPP connection. After a fresh install of NetBSD they don't exist
380: and must be created (chmod 700).
381:
382: # mkdir /etc/ppp
383: # mkdir /etc/ppp/peers
384:
385: ### Connection script and chat file
386:
387: The connection script will be used as a parameter on the pppd command line; it
388: is located in `/etc/ppp/peers` and has usually the name of the provider. For
389: example, if the provider's name is BigNet and your user name for the connection
390: to the provider is alan, an example connection script could be:
391:
392: # /etc/ppp/peers/bignet
393: connect '/usr/sbin/chat -v -f /etc/ppp/peers/bignet.chat'
394: noauth
395: user alan
396: remotename bignet.it
397:
398: In the previous example, the script specifies a *chat file* to be used for the
399: connection. The options in the script are detailed in the
400: [pppd(8)](http://netbsd.gw.com/cgi-bin/man-cgi?pppd+8+NetBSD-5.0.1+i386) man
401: page.
402:
403: ### Note
404:
405: If you are experiencing connection problems, add the following two lines to the
406: connection script
407:
408: debug
409: kdebug 4
410:
411: You will get a log of the operations performed when the system tries to connect.
412: See [pppd(8)](http://netbsd.gw.com/cgi-bin/man-cgi?pppd+8+NetBSD-5.0.1+i386),
413: [syslog.conf(5)](http://netbsd.gw.com/cgi-bin/man-cgi?syslog.conf+5+NetBSD-5.0.1+i386).
414:
415: The connection script calls the chat application to deal with the physical
416: connection (modem initialization, dialing, ...) The parameters to chat can be
417: specified inline in the connection script, but it is better to put them in a
418: separate file. If, for example, the telephone number of the POP to call is
419: `02 99999999`, an example chat script could be:
420:
421: # /etc/ppp/peers/bignet.chat
422: ABORT BUSY
423: ABORT "NO CARRIER"
424: ABORT "NO DIALTONE"
425: '' ATDT0299999999
426: CONNECT ''
427:
428: *Note*: If you have problems with the chat file, you can try connecting manually
429: to the POP with the
430: [cu(1)](http://netbsd.gw.com/cgi-bin/man-cgi?cu+1+NetBSD-5.0.1+i386) program and
431: verify the exact strings that you are receiving.
432:
433: ### Authentication
434:
435: During authentication each of the two systems verifies the identity of the other
436: system, although in practice you are not supposed to authenticate the provider,
437: but only to be verified by him, using one of the following methods:
438:
439: * PAP/CHAP
440: * login
441:
442: Most providers use a PAP/CHAP authentication.
443:
444: #### PAP/CHAP authentication
445:
446: The authentication information (speak: password) is stored in the
447: `/etc/ppp/pap-secrets` for PAP and in `/etc/ppp/chap-secrets` for CHAP. The
448: lines have the following format:
449:
450: user * password
451:
452: For example:
453:
454: alan * pZY9o
455:
456: For security reasons the `pap-secrets` and `chap-secrets` files should be owned
457: by root and have permissions 600.
458:
459: # chown root /etc/ppp/pap-secrets
460: # chown root /etc/ppp/chap-secrets
461: # chmod 600 /etc/ppp/pap-secrets
462: # chmod 600 /etc/ppp/chap-secrets
463:
464: #### Login authentication
465:
466: This type of authentication is not widely used today; if the provider uses login
467: authentication, user name and password must be supplied in the chat file instead
468: of the PAP/CHAP files, because the chat file simulates an interactive login. In
469: this case, set up appropriate permissions for the chat file.
470:
471: The following is an example chat file with login authentication:
472:
473: # /etc/ppp/peers/bignet.chat
474: ABORT BUSY
475: ABORT "NO CARRIER"
476: ABORT "NO DIALTONE"
477: '' ATDT0299999999
478: CONNECT ''
479: TIMEOUT 50
480: ogin: alan
481: ssword: pZY9o
482:
483: ### pppd options
484:
485: The only thing left to do is the creation of the pppd options file, which is
486: `/etc/ppp/options` (chmod 644):
487:
488: /dev/tty01
489: lock
490: crtscts
491: 57600
492: modem
493: defaultroute
494: noipdefault
495:
496: Check the
497: [pppd(8)](http://netbsd.gw.com/cgi-bin/man-cgi?pppd+8+NetBSD-5.0.1+i386) man
498: page for the meaning of the options.
499:
500: ### Testing the modem
501:
502: Before activating the link it is a good idea to make a quick modem test, in
503: order to verify that the physical connection and the communication with the
504: modem works. For the test the
505: [cu(1)](http://netbsd.gw.com/cgi-bin/man-cgi?cu+1+NetBSD-5.0.1+i386) program can
506: be used, as in the following example.
507:
508: 1. Create the file `/etc/uucp/port` with the following lines:
509:
510: type modem
511: port modem
512: device /dev/tty01
513: speed 115200
514:
515: (substitute the correct device in place of `/dev/tty01`).
516:
517: 2. Write the command `cu -p modem` to start sending commands to the modem. For
518: example:
519:
520: # cu -p modem
521: Connected.
522: ATZ
523: OK
524: ~.
525:
526: Disconnected.
527: #
528:
529: In the previous example the reset command (ATZ) was sent to the modem, which
530: replied with OK: the communication works. To exit
531: [cu(1)](http://netbsd.gw.com/cgi-bin/man-cgi?cu+1+NetBSD-5.0.1+i386), write
532: `~` (tilde) followed by `.` (dot), as in the example.
533:
534: If the modem doesn't work, check that it is connected to the correct port (i.e.
535: you are using the right port with
536: [cu(1)](http://netbsd.gw.com/cgi-bin/man-cgi?cu+1+NetBSD-5.0.1+i386). Cables are
537: a frequent cause of trouble, too.
538:
539: When you start
540: [cu(1)](http://netbsd.gw.com/cgi-bin/man-cgi?cu+1+NetBSD-5.0.1+i386) and a
541: message saying `Permission denied` appears, check who is the owner of the
542: `/dev/tty##` device, it must be "uucp". For example:
543:
544: $ ls -l /dev/tty00
545: crw------- 1 uucp wheel 8, 0 Mar 22 20:39 /dev/tty00
546:
547: If the owner is root, the following happens:
548:
549: $ ls -l /dev/tty00
550: crw------- 1 root wheel 8, 0 Mar 22 20:39 /dev/tty00
551: $ cu -p modem
552: cu: open (/dev/tty00): Permission denied
553: cu: All matching ports in use
554:
555: ### Activating the link
556:
557: At last everything is ready to connect to the provider with the following
558: command:
559:
560: # pppd call bignet
561:
562: where `bignet` is the name of the already described connection script. To see
563: the connection messages of pppd, give the following command:
564:
565: # tail -f /var/log/messages
566:
567: To disconnect, do a **kill -HUP** of **pppd**.
568:
569: # pkill -HUP pppd
570:
571: ### Using a script for connection and disconnection
572:
573: When the connection works correctly, it's time to write a couple of scripts to
574: avoid repeating the commands every time. These two scripts can be named, for
575: example, `ppp-start` and `ppp-stop`.
576:
577: `ppp-start` is used to connect to the provider:
578:
579: #!/bin/sh
580: MODEM=tty01
581: POP=bignet
582: if [ -f /var/spool/lock/LCK..$MODEM ]; then
583: echo ppp is already running...
584: else
585: pppd call $POP
586: tail -f /var/log/messages
587: fi
588:
589: `ppp-stop` is used to close the connection:
590:
591: #!/bin/sh
592: MODEM=tty01
593: if [ -f /var/spool/lock/LCK..$MODEM ]; then
594: echo -f killing pppd...
595: kill -HUP `cat /var/spool/lock/LCK..$MODEM`
596: echo done
597: else
598: echo ppp is not active
599: fi
600:
601: The two scripts take advantage of the fact that when pppd is active, it creates
602: the file `LCK..tty01` in the `/var/spool/lock` directory. This file contains the
603: process ID (*pid*) of the pppd process.
604:
605: The two scripts must be executable:
606:
607: # chmod u+x ppp-start ppp-stop
608:
609: ### Running commands after dialin
610:
611: If you find yourself to always run the same set of commands each time you dial
612: in, you can put them in a script `/etc/ppp/ip-up` which will be called by
613: [pppd(8)](http://netbsd.gw.com/cgi-bin/man-cgi?pppd+8+NetBSD-5.0.1+i386) after
614: successful dial-in. Likewise, before the connection is closed down,
615: `/etc/ppp/ip-down` is executed. Both scripts are expected to be executable. See
616: [pppd(8)](http://netbsd.gw.com/cgi-bin/man-cgi?pppd+8+NetBSD-5.0.1+i386) for
617: more details.
618:
619: ## Creating a small home network
620:
621: Networking is one of the main strengths of Unix and NetBSD is no exception:
622: networking is both powerful and easy to set up and inexpensive too, because
623: there is no need to buy additional software to communicate or to build a server.
624: [[Setting up an Internet gateway with IPNAT|guide/net-practice#ipnat]] explains
625: how to configure a NetBSD machine to act as a gateway for a network: with IPNAT
626: all the hosts of the network can reach the Internet with a single connection to
627: a provider made by the gateway machine. The only thing to be checked before
628: creating the network is to buy network cards supported by NetBSD (check the
629: `INSTALL.*` files for a list of supported devices).
630:
631: First, the network cards must be installed and connected to a hub, switch or
632: directly (see the next image for an example configuration).
633:
634: Next, check that the network cards are recognized by the kernel, studying the
635: output of the `dmesg` command. In the following example the kernel recognized
636: correctly an NE2000 clone:
637:
638: ...
639: ne0 at isa0 port 0x280-0x29f irq 9
640: ne0: NE2000 Ethernet
641: ne0: Ethernet address 00:c2:dd:c1:d1:21
642: ...
643:
644: If the card is not recognized by the kernel, check that it is enabled in the
645: kernel configuration file and then that the card's IRQ matches the one that the
646: kernel expects. For example, this is the isa NE2000 line in the configuration
647: file; the kernel expects the card to be at IRQ 9.
648:
649: ...
650: ne0 at isa? port 0x280 irq 9 # NE[12]000 ethernet cards
651: ...
652:
653: If the card's configuration is different, it will probably not be found at boot.
654: In this case, either change the line in the kernel configuration file and
655: compile a new kernel or change the card's setup (usually through a setup disk
656: or, for old cards, a jumper on the card).
657:
658: The following command shows the network card's current configuration:
659:
660: # ifconfig ne0
661: ne0: flags=8822<BROADCAST,NOTRAILERS,SIMPLEX,MULTICAST> mtu 1500
662: address: 00:50:ba:aa:a7:7f
663: media: Ethernet autoselect (10baseT)
664: inet6 fe80::250:baff:feaa:a77f%ne0 prefixlen 64 scopeid 0x1
665:
666: The software configuration of the network card is very easy. The IP address
667: 192.168.1.1 is assigned to the card.
668:
669: # ifconfig ne0 inet 192.168.1.1 netmask 0xffffff00
670:
671: Note that the networks 10.0.0.0/8 and 192.168.0.0/16 are reserved for private
672: networks, which is what we're setting up here.
673:
674: Repeating the previous command now gives a different result:
675:
676: # ifconfig ne0
677: ne0: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 1500
678: address: 00:50:ba:aa:a7:7f
679: media: Ethernet autoselect (10baseT)
680: inet 192.168.1.1 netmask 0xffffff00 broadcast 192.168.1.255
681: inet6 fe80::250:baff:feaa:a77f%ne0 prefixlen 64 scopeid 0x1
682:
683: The output of `ifconfig` has now changed: the IP address is now printed and
684: there are two new flags, `UP` and `RUNNING` If the interface isn't `UP`, it will
685: not be used by the system to send packets.
686:
687: The host was given the IP address 192.168.1.1, which belongs to the set of
688: addresses reserved for internal networks which are not reachable from the
689: Internet. The configuration is finished and must now be tested; if there is
690: another active host on the network, a `ping` can be tried. For example, if
691: 192.168.1.2 is the address of the active host:
692:
693: # ping 192.168.1.2
694: PING ape (192.168.1.2): 56 data bytes
695: 64 bytes from 192.168.1.2: icmp_seq=0 ttl=255 time=1.286 ms
696: 64 bytes from 192.168.1.2: icmp_seq=1 ttl=255 time=0.649 ms
697: 64 bytes from 192.168.1.2: icmp_seq=2 ttl=255 time=0.681 ms
698: 64 bytes from 192.168.1.2: icmp_seq=3 ttl=255 time=0.656 ms
699: ^C
700: ----ape PING Statistics----
701: 4 packets transmitted, 4 packets received, 0.0% packet loss
702: round-trip min/avg/max/stddev = 0.649/0.818/1.286/0.312 ms
703:
704: With the current setup, at the next boot it will be necessary to repeat the
705: configuration of the network card. In order to avoid repeating the card's
706: configuration at each boot, add the following lines to `/etc/rc.conf`:
707:
708: auto_ifconfig=yes
709: ifconfig_ne0="inet 192.168.1.1 netmask 0xffffff00"
710:
711: In this example the variable `ifconfig_ne0` was set because the network card was
712: recognized as *ne0* by the kernel; if you are using a different adapter,
713: substitute the appropriate name in place of ne0.
714:
715: At the next boot the network card will be configured automatically.
716:
717: If you have a router that is connected to the internet, you can use it as
718: default router, which will handle all your packets. To do so, set `defaultroute`
719: to the router's IP address in `/etc/rc.conf`:
720:
721: defaultroute=192.168.0.254
722:
723: Be sure to use the default router's IP address instead of name, in case your DNS
724: server is beyond the default router. In that case, the DNS server couldn't be
725: reached to resolve the default router's hostname and vice versa, creating a
726: chicken-and-egg problem.
727:
728: To reach hosts on your local network, and assuming you really have very few
729: hosts, adjust `/etc/hosts` to contain the addresses of all the hosts belonging
730: to the internal network. For example:
731:
732: #
733: # Host Database
734: # This file should contain the addresses and aliases
735: # for local hosts that share this file.
736: # It is used only for "ifconfig" and other operations
737: # before the nameserver is started.
738: #
739: #
740: 127.0.0.1 localhost
741: ::1 localhost
742: #
743: # RFC 1918 specifies that these networks are "internal".
744: # 10.0.0.0 10.255.255.255
745: # 172.16.0.0 172.31.255.255
746: # 192.168.0.0 192.168.255.255
747:
748: 192.168.1.1 ape.insetti.net ape
749: 192.168.1.2 vespa.insetti.net vespa
750: 192.168.1.0 insetti.net
751:
752: If you are dialed in via an Internet Service Provider, or if you have a local
753: Domain Name Server (DNS) running, you may want to use it to resolve hostnames to
754: IP addresses, possibly in addition to `/etc/hosts`, which would only know your
755: own hosts. To configure a machine as DNS client, you need to edit
756: `/etc/resolv.conf`, and enter the DNS server's address, in addition to an
757: optional domain name that will be appended to hosts with no domain, in order to
758: create a FQDN for resolving. Assuming your DNS server's IP address is
759: 192.168.1.2 and it is setup to serve for "home.net", put the following into
760: `/etc/resolv.conf`:
761:
762: # /etc/resolv.conf
763: domain home.net
764: nameserver 192.168.1.2
765:
766: The `/etc/nsswitch.conf` file should be checked as explained in the previous
767: [[nsswitch.conf example|guide/net-practice#rc.conf_and_nsswitch.conf]].
768:
769: Summing up, to configure the network the following must be done: the network
770: adapters must be installed and physically connected. Next they must be
771: configured (with **ifconfig**) and, finally, the file `/etc/rc.conf` must be
772: modified to configure the interface and possibly default router, and
773: `/etc/resolv.conf` and `/etc/nsswitch.conf` should be adjusted if DNS should be
774: used. This type of network management is sufficient for small networks without
775: sophisticated needs.
776:
777: ## Setting up an Internet gateway with IPNAT
778:
779: The mysterious acronym IPNAT hides the Internet Protocol Network Address
780: Translation, which enables the routing of an internal network (e.g. your home
781: network as described in the previous section) on a real network (Internet). This
782: means that with only one *real* IP, static or dynamic, belonging to a gateway
783: running IPNAT, it is possible to create simultaneous connections to the Internet
784: for all the hosts of the internal network.
785:
786: Some usage examples of IPNAT can be found in the subdirectory
787: `/usr/share/examples/ipf`: look at the files `BASIC.NAT` and `nat-setup`.
788:
789: The setup for the example described in this section is detailed in the following
790: figure: *host 1* can connect to the Internet calling a provider with a modem and
791: getting a dynamic IP address. *host 2* and *host 3* can't communicate with the
792: Internet with a normal setup: IPNAT allows them to do it: host 1 will act as a
793: Internet gateway for hosts 2 and 3. Using host 1 as default router, hosts 2 and
794: 3 will be able to access the Internet.
795:
796: 
797: **Network with gateway**
798:
799: ### Configuring the gateway/firewall
800:
801: To use IPNAT, the *pseudo-device ipfilter* must be compiled into the kernel, and
802: IP packet forwarding must be enabled in the kernel. To check, run:
803:
804: # sysctl net.inet.ip.forwarding
805: net.inet.ip.forwarding = 1
806:
807: If the result is `1` as in the previous example, the option is enabled,
808: otherwise, if the result is `0` the option is disabled. You can do two things:
809:
810: 1. Compile a new kernel, with the GATEWAY option enabled.
811:
812: 2. Enable the option in the current kernel with the following command:
813:
814: # sysctl -w net.inet.ip.forwarding=1
815:
816: You can add sysctl settings to `/etc/sysctl.conf` to have them set
817: automatically at boot. In this case you would want to add
818:
819: net.inet.ip.forwarding=1
820:
821:
822: The rest of this section explains how to create an IPNAT configuration that is
823: automatically started every time that a connection to the provider is activated
824: with the PPP link. With this configuration all the host of a home network (for
825: example) will be able to connect to the Internet through the gateway machine,
826: even if they don't use NetBSD.
827:
828: For the setup, first, create the `/etc/ipnat.conf` file containing the following
829: rules:
830:
831: map ppp0 192.168.1.0/24 -> 0/32 proxy port ftp ftp/tcp
832: map ppp0 192.168.1.0/24 -> 0/32 portmap tcp/udp 40000:60000
833: map ppp0 192.168.1.0/24 -> 0/32
834:
835: 192.168.1.0/24 are the network addresses that should be mapped. The first line
836: of the configuration file is optional: it enables active FTP to work through the
837: gateway. The second line is used to handle correctly tcp and udp packets; the
838: portmapping is necessary because of the many to one relationship). The third
839: line is used to enable ICMP, ping, etc.
840:
841: Next, create the `/etc/ppp/ip-up` file; it will be called automatically every
842: time that the PPP link is activated:
843:
844: #!/bin/sh
845: # /etc/ppp/ip-up
846: /etc/rc.d/ipnat forcestart
847:
848: Create the file `/etc/ppp/ip-down`; it will be called automatically when the PPP
849: link is closed:
850:
851: #!/bin/sh
852: # /etc/ppp/ip-down
853: /etc/rc.d/ipnat forcestop
854:
855: Both `ip-up` and `ip-down` must be executable:
856:
857: # chmod u+x ip-up ip-down
858:
859: The gateway machine is now ready.
860:
861: ### Configuring the clients
862:
863: Create a `/etc/resolv.conf` file like the one on the gateway machine, to make
864: the clients access the same DNS server as the gateway.
865:
866: Next, make all clients use the gateway as their default router. Use the
867: following command:
868:
869: # route add default 192.168.1.1
870:
871: 192.168.1.1 is the address of the gateway machine configured in the previous
872: section.
873:
874: Of course you don't want to give this command every time, so it's better to
875: define the `defaultroute` entry in the `/etc/rc.conf` file: the default route
876: will be set automatically during system initialization, using the defaultroute
877: option as an argument to the **route add default** command.
878:
879: If the client machine is not using NetBSD, the configuration will be different.
880: On Windows PCs you need to set the gateway property of the TCP/IP protocol to
881: the IP address of the NetBSD gateway.
882:
883: That's all that needs to be done on the client machines.
884:
885: ### Some useful commands
886:
887: The following commands can be useful for diagnosing problems:
888:
889: * `ping` -- tries to connect to other computers via ICMP (usually used for
890: testing if a connection exists).
891: * `netstat -r` -- Displays the routing tables (similar to **route show**).
892: * `traceroute` -- On the client it shows the route followed by the packets to
893: their destination.
894: * `tcpdump` -- Use on the gateway to monitor TCP/IP traffic.
895:
896: ## Setting up a network bridge device
897:
898: A bridge can be used to combine different physical networks into one logical
899: network, i.e. connect them at layer 2 of the ISO-OSI model, not at layer 3,
900: which is what a router would do. The NetBSD `bridge` driver provides bridge
901: functionality on NetBSD systems.
902:
903: ### Bridge example
904:
905: In this example two physical networks are going to be combined in one logical
906: network, 192.168.1.0, using a NetBSD bridge. The NetBSD machine which is going
907: to act as bridge has two interfaces, ne0 and ne1, which are each connected to
908: one physical network.
909:
910: The first step is to make sure support for the `bridge` is compiled in the
911: running kernel. Support is included in the GENERIC kernel.
912:
913: When the system is ready the bridge can be created, this can be done using the
914: [brconfig(8)]((http://netbsd.gw.com/cgi-bin/man-cgi?brconfig+8+NetBSD-current))
915: command. First of a bridge interface has to be created. With the following
916: `ifconfig` command the `bridge0` interface will be created:
917:
918: $ ifconfig bridge0 create
919:
920: Please make sure that at this point both the ne0 and ne1 interfaces are up. The
921: next step is to add the ne0 and ne1 interfaces to the bridge.
922:
923: $ brconfig bridge0 add ne0 add ne1 up
924:
925: This configuration can be automatically set up by creating an
926: `/etc/ifconfig.interface` file, in this case `/etc/ifconfig.bridge0`, with the
927: following contents:
928:
929: create
930: !brconfig $int add ne0 add ne1 up
931:
932: After setting up the bridge the bridge configuration can be displayed using the
933: `brconfig -a` command. Remember that if you want to give the bridge machine an
934: IP address you can only allocate an IP address to one of the interfaces which
935: are part of the bridge.
936:
937: ## A common LAN setup
938:
939: The small home network discussed in the previous section contained many items
940: that were configured manually. In bigger LANs that are centrally managed, one
941: can expect Internet connectivity being available via some router, a DNS server
942: being available, and most important, a DHCP server which hands out IP addresses
943: to clients on request. To make a NetBSD client run in such an environment, it's
944: usually enough to set
945:
946: dhclient=yes
947:
948: in `/etc/rc.conf`, and the IP address will be set automatically,
949: `/etc/resolv.conf` will be created and routing setup to the default router.
950:
951: ## Connecting two PCs through a serial line
952:
953: If you need to transfer files between two PCs which are not networked there is a
954: simple solution which is particularly handy when copying the files to a floppy
955: is not practical: the two machines can be networked with a serial cable (a *null
956: modem* cable). The following sections describe some configurations.
957:
958: ### Connecting NetBSD with BSD or Linux
959:
960: The easiest case is when both machines run NetBSD: making a connection with the
961: SLIP protocol is very easy. On the first machine write the following commands:
962:
963: # slattach /dev/tty00
964: # ifconfig sl0 inet 192.168.1.1 192.168.1.2
965:
966: On the second machine write the following commands:
967:
968: # slattach /dev/tty00
969: # ifconfig sl0 inet 192.168.1.2 192.168.1.1
970:
971: Now you can test the connection with `ping`; for example, on the second PC
972: write:
973:
974: # ping 192.168.1.1
975:
976: If everything worked there is now an active network connection between the two
977: machines and ftp, telnet and other similar commands can be executed. The textual
978: aliases of the machines can be written in the `/etc/hosts` file.
979:
980: * In the previous example both PCs used the first serial port (`/dev/tty0`).
981: Substitute the appropriate device if you are using another port.
982:
983: * IP addresses like 192.168.x.x are reserved for `internal` networks. The first
984: PC has address 192.168.1.1 and the second 192.168.1.2.
985:
986: * To achieve a faster connection the `-s speed` option to `slattach` can be
987: specified.
988:
989: * `ftp` can be used to transfer files only if inetd is active and the ftpd
990: * server is enabled.
991:
992: ### Linux
993:
994: If one of the two PCs runs Linux, the commands are slightly different (on the
995: Linux machine only). If the Linux machine gets the 192.168.1.2 address, the
996: following commands are needed:
997:
998: # slattach -p slip -s 115200 /dev/ttyS0 &
999: # ifconfig sl0 192.168.1.2 pointopoint 192.168.1.1 up
1000: # route add 192.168.1.1 dev sl0
1001:
1002: Don't forget the `&` in the first command.
1003:
1004: ### Connecting NetBSD and Windows NT
1005:
1006: NetBSD and Windows NT can be (almost) easily networked with a serial *null
1007: modem* cable. Basically what needs to be done is to create a *Remote Access*
1008: connection under Windows NT and to start pppd on NetBSD.
1009:
1010: Start pppd as root after having created a `.ppprc` in `/root`. Use the following
1011: example as a template.
1012:
1013: connect '/usr/sbin/chat -v CLIENT CLIENTSERVER'
1014: local
1015: tty00
1016: 115200
1017: crtscts
1018: lock
1019: noauth
1020: nodefaultroute
1021: :192.168.1.2
1022:
1023: The meaning of the first line will be explained later in this section;
1024: 192.168.1.2 is the IP address that will be assigned by NetBSD to the Windows NT
1025: host; `tty00` is the serial port used for the connection (first serial port).
1026:
1027: On the NT side a *null modem* device must be installed from the Control Panel
1028: (Modem icon) and a Remote Access connection using this modem must be created.
1029: The null modem driver is standard under Windows NT 4 but it's not a 100% null
1030: modem: when the link is activated, NT sends the string CLIENT and expects to
1031: receive the answer CLIENTSERVER. This is the meaning of the first line of the
1032: `.ppprc` file: `chat` must answer to NT when the connection is activated or
1033: the connection will fail.
1034:
1035: In the configuration of the Remote Access connection the following must be
1036: specified: use the null modem, telephone number `1` (it's not used, anyway), PPP
1037: server, enable only TCP/IP protocol, use IP address and nameservers from the
1038: server (NetBSD in this case). Select the hardware control flow and set the port
1039: to 115200 8N1.
1040:
1041: Now everything is ready to activate the connection.
1042:
1043: * Connect the serial ports of the two machines with the null modem cable.
1044: * Launch pppd on NetBSD. To see the messages of pppd:
1045: `tail -f /var/log/messages`).
1046: * Activate the Remote Access connection on Windows NT.
1047:
1048: ### Connecting NetBSD and Windows 95
1049:
1050: The setup for Windows 95 is similar to the one for Windows NT: Remote Access on
1051: Windows 95 and the PPP server on NetBSD will be used. Most (if not all) Windows
1052: 95 releases don't have the *null modem* driver, which makes things a little more
1053: complicated. The easiest solution is to find one of the available null modem
1054: drivers on the Internet (it's a small `.INF` file) and repeat the same steps as
1055: for Windows NT. The only difference is that the first line of the `.ppprc` file
1056: (the one that calls `chat`) can be removed.
1057:
1058: If you can't find a real null modem driver for Windows 95 it's still possible to
1059: use a little trick:
1060:
1061: * Create a Remote Access connection like the one described before for Windows
1062: NT, but using the *Standard Modem*.
1063:
1064: * In `.ppprc` substitute the line that calls **chat** with the following line
1065:
1066: connect '/usr/sbin/chat -v ATH OK AT OK ATE0V1 OK AT OK ATDT CONNECT'
1067:
1068: * Activate the connection as described in the section before for Windows NT.
1069:
1070:
1071: In this way the `chat` program, called when the connection is activated,
1072: emulates what Windows 95 thinks is a standard modem, returning to Windows 95 the
1073: same answers that a standard modem would return. Whenever Windows 95 sends a
1074: modem command string, `chat` returns OK.
1075:
1076: ## IPv6 Connectivity & Transition via 6to4
1077:
1078: This section will concentrate on how to get network connectivity for IPv6 and -
1079: as that is rarely available directly - talk at length about the alternatives to
1080: native IPv6 connectivity as a transitional method until native IPv6 peers are
1081: available.
1082:
1083: Finding an ISP that offers IPv6 natively needs quite some luck. What you need
1084: next is a router that will be able to handle the traffic. To date, not all
1085: router manufacturers offer IPv6 or hardware accelerated IPv6 features, and
1086: gateway NAT boxes only rarely support IPv6 and also block IPv6 tunnels. An
1087: alternative approach involves configuring a standard PC running NetBSD to act as
1088: a router. The base NetBSD system contains a complete IPv6 routing solution, and
1089: for special routing needs software like Zebra can provide additional routing
1090: protocols. This solution is rather common for sites that want IPv6
1091: connectivity today. The drawbacks are that you need an ISP that supports
1092: IPv6 and that you may need a dedicated uplink only for IPv6.
1093:
1094: IPv6 to-the-door may be rare, but you can still get IPv6 connectivity by using
1095: tunnels. Instead of talking IPv6 on the wire, the IPv6 packets are encapsulated
1096: in IPv4 packets, as shown in the next image. Using the existing IPv4
1097: infrastructure, the encapsulated packets are sent to a IPv6-capable uplink that
1098: will then remove the encapsulation, and forward the IPv6 packets.
1099:
1100: 
1101: **A frequently used method for transition is tunneling IPv6 in IPv4 packets**
1102:
1103: When using tunnels, there are two possibilities. One is to use a so-called
1104: *configured* tunnel, the other is called an *automatic* tunnel. A *configured*
1105: tunnel is one that required preparation from both ends of the tunnel, usually
1106: connected with some kind of registration to exchange setup information. An
1107: example for such a configured tunnel is the IPv6-over-IPv4 encapsulation
1108: described in
1109: [RFC1933](http://tools.ietf.org/html/rfc1933) ("RFC 1933: Transition Mechanisms
1110: for IPv6 Hosts and Routers"), and that's implemented e.g. by the
1111: [gif(4)](http://netbsd.gw.com/cgi-bin/man-cgi?gif+4+NetBSD-5.0.1+i386)
1112: device found in NetBSD.
1113:
1114: An *automatic* tunnel consists of a public server that has some kind of IPv6
1115: connectivity, e.g. via 6Bone. That server has made its connectivity data public,
1116: and also runs a tunneling protocol that does not require an explicit
1117: registration of the sites using it as uplink. A well-used example of such a
1118: protocol is the 6to4 mechanism described in
1119: [RFC3056](http://tools.ietf.org/html/rfc3056) ("RFC 3056: Connection of IPv6
1120: Domains via IPv4 Clouds"), and that is implemented in the
1121: [stf(4)](http://netbsd.gw.com/cgi-bin/man-cgi?stf+4+NetBSD-5.0.1+i386) device
1122: found in NetBSD's. Another mechanism that does not require registration of
1123: IPv6-information is the 6over4 mechanism, which implements transporting of IPv6
1124: over a multicast-enabled IPv4 network, instead of e.g. ethernet or FDDI. 6over4
1125: is documented in [RFC2529](http://tools.ietf.org/html/rfc2529) ("RFC 2529:
1126: Transmission of IPv6 over IPv4 Domains without Explicit Tunnels"). It's main
1127: drawback is that you do need existing multicast infrastructure. If you don't
1128: have that, setting it up is about as much effort as setting up a configured IPv6
1129: tunnel directly, so it's usually not worth bothering in that case.
1130:
1131: ### Getting 6to4 IPv6 up & running
1132:
1133: 6to4 is an easy way to get IPv6 connectivity for hosts that only have an IPv4
1134: uplink, especially if you have the background given in
1135: [[the chapter about IPv6|guide/net-intro#ipv6-intro]]. It can be used with
1136: static as well as dynamically assigned IPv4 addresses, e.g. as found in modem
1137: dialup scenarios today. When using dynamic IPv4 addresses, a change of IP
1138: addresses will be a problem for incoming traffic, i.e. you can't run persistent
1139: servers.
1140:
1141: Example configurations given in this section are for NetBSD 1.5.2.
1142:
1143: ### Obtaining IPv6 Address Space for 6to4
1144:
1145: The 6to4 IPv6 setup on your side doesn't consist of a single IPv6 address;
1146: Instead, you get a whole /48 network! The IPv6 addresses are derived from your
1147: (single) IPv4 address. The address prefix *2002:` is reserved for 6to4 based
1148: addresses (i.e. IPv6 addresses derived from IPv4 addresses). The next 32 bits
1149: are your IPv4 address. This results in a /48 network that you can use for your
1150: very own purpose. It leaves 16 bits space for 2^16^ IPv6 subnets, which can take
1151: up to 2^64^ nodes each. The next figure illustrates the building of your IPv6
1152: address (range) from your IPv4 address.
1153:
1154: Thanks to the 6to4 prefix and your worldwide unique IPv4 address, this address
1155: block is unique, and it's mapped to your machine carrying the IPv4 address in
1156: question.
1157:
1158: 
1159: **6to4 derives an IPv6 from an IPv4 address**
1160:
1161: ### How to get connected
1162:
1163: In contrast to the configured *IPv6-over-IPv4 tunnel* setup, you do not have to
1164: register at a 6bone-gateway, which would only then forward your IPv6 traffic
1165: encapsulated in IPv4. Instead, as your IPv6 address is derived from your IPv4
1166: address, inbound traffic can be sent through the nearest 6to4 relay router.
1167: De-encapsulation of the packet is done via a 6to4-capable network interface,
1168: which then forwards the resulting IPv6 packet according to your routing setup
1169: (in case you have more than one machine connected on your 6to4 assigned
1170: network).
1171:
1172: To transmit IPv6 packets, the 6to4 router will encapsulate them inside IPv4
1173: packets; a system performing these functions is called a 6to4 border router.
1174: These packets have a default route to the *6to4 relay anycast prefix*. This
1175: anycast prefix will route the tunnel to a *6to4 relay router*.
1176:
1177: 
1178: **Request and reply can be routed via different gateways in 6to4**
1179:
1180: ### Security Considerations
1181:
1182: In contrast to the *configured tunnel* setup, you usually can't setup packet
1183: filters to block 6to4-packets from unauthorized sources, as this is exactly how
1184: (and why) 6to4 works at all. As such, malicious users can send packets with
1185: invalid/hazardous IPv6 payload. If you don't already filter on your border
1186: gateways anyways, packets with the following characteristics should not be
1187: allowed as valid 6to4 packets, and some firewalling seems to be justified for
1188: them:
1189:
1190: * unspecified IPv4 source/destination address: 0.0.0.0/8
1191: * loopback address in outer (v4) source/destination: 127.0.0.0/8
1192: * IPv4 multicast in source/destination: 224.0.0.0/4
1193: * limited broadcasts: 255.0.0.0/8
1194: * subnet broadcast address as source/destination: depends on your IPv4 setup
1195:
1196: The NetBSD
1197: [stf(4)](http://netbsd.gw.com/cgi-bin/man-cgi?stf+4+NetBSD-5.0.1+i386) manual
1198: page documents some common configuration mistakes intercepted by default by the
1199: KAME stack as well as some further advice on filtering, but keep in mind that
1200: because of the requirement of these filters, 6to4 is not perfectly secure.
1201: Still, if forged 6to4 packets become a problem, you can use IPsec authentication
1202: to ensure the IPv6 packets are not modified.
1203:
1204: ### Data Needed for 6to4 Setup
1205:
1206: In order to setup and configure IPv6 over 6to4, a few bits of configuration data
1207: must be known in advance. These are:
1208:
1209: * Your local IPv4 address. It can be determined using either the `ifconfig -a`
1210: or `netstat -i` commands on most Unix systems. If you use a NATing gateway or
1211: something, be sure to use the official, outside-visible address, not your
1212: private (10/8 or 192.168/16) one.
1213:
1214: We will use 62.224.57.114 as the local IPv4 address in our example.
1215:
1216: * Your local IPv6 address, as derived from the IPv4 address. See the previous
1217: figure ("6to4 derives an IPv6 from an IPv4 address") about how to do so.
1218:
1219: For our example, this is 2002:3ee0:3972:0001::1 (62.224.57.114 == 0x3ee03972,
1220: 0001::1 arbitrarily chosen).
1221:
1222: * The *6to4 IPv6 relay anycast address*. which is 2002:c058:6301::, or the IPv6
1223: address of a specific 6to4 relay router you want to use. The IPv6 address
1224: will do, as it also contains the IPv4 address in the usual 6to4 translation.
1225:
1226: ### Kernel Preparation
1227:
1228: To process 6to4 packets, the operating system kernel needs to know about them.
1229: For that a driver has to be compiled in that knows about 6to4, and how to handle
1230: it. In NetBSD 4.0 and newer, the driver is already present in GENERIC kernel
1231: configurations, so the procedure below is usually unnecessary.
1232:
1233: For a NetBSD kernel, put the following into your kernel config file to prepare
1234: it for using IPv6 and 6to4, e.g. on NetBSD use:
1235:
1236: options INET6 # IPv6
1237: pseudo-device stf # 6to4 IPv6 over IPv4 encapsulation
1238:
1239: Note that the
1240: [stf(4)](http://netbsd.gw.com/cgi-bin/man-cgi?stf+4+NetBSD-5.0.1+i386) device is
1241: not enabled by default on NetBSD releases older than 4.0. Rebuild your kernel,
1242: then reboot your system to use the new kernel. Please consult
1243: [[Compiling the kernel|guide/kernel]] for further information on configuring,
1244: building and installing a new kernel!
1245:
1246: ### 6to4 Setup
1247:
1248: This section describes the commands to setup 6to4. In short, the steps performed
1249: here are:
1250:
1251: 1. Configure interface
1252: 2. Set default route
1253: 3. Setup Router Advertisement, if wanted
1254:
1255: The first step in setting up 6to4 is creating the 6to4 interface and assigning
1256: an IPv6 address to it. This is achieved with the
1257: [ifconfig(8)](http://netbsd.gw.com/cgi-bin/man-cgi?ifconfig+8+NetBSD-5.0.1+i386)
1258: command. Assuming the example configuration above, the commands for NetBSD are:
1259:
1260: # ifconfig stf0 create
1261: # ifconfig stf0 inet6 2002:3ee0:3972:1::1 prefixlen 16 alias
1262:
1263: After configuring the 6to4 device with these commands, routing needs to be
1264: setup, to forward all tunneled IPv6 traffic to the 6to4 relay router. The best
1265: way to do this is by setting a default route, the command to do so is, for
1266: NetBSD:
1267:
1268: # route add -inet6 default 2002:c058:6301::
1269:
1270: Note that NetBSD's
1271: [stf(4)](http://netbsd.gw.com/cgi-bin/man-cgi?stf+4+NetBSD-5.0.1+i386) device
1272: determines the IPv4 address of the 6to4 uplink from the routing table. Using
1273: this feature, it is easy to setup your own 6to4 (uplink) gateway if you have an
1274: IPv6 uplink, e.g. via 6Bone.
1275:
1276: After these commands, you are connected to the IPv6-enabled world -
1277: Congratulations! Assuming name resolution is still done via IPv4, you can now
1278: ping an IPv6-site like www.kame.net or www6.NetBSD.org:
1279:
1280: # /sbin/ping6 www.kame.net
1281:
1282: As a final step in setting up IPv6 via 6to4, you will want to setup Router
1283: Advertisement if you have several hosts on your network. While it is possible to
1284: setup 6to4 on each node, doing so will result in very expensive routing from one
1285: node to the other - packets will be sent to the remote 6to4 gateway, which will
1286: then route the packets back to the neighbor node. Instead, setting up 6to4 on
1287: one machine and talking native IPv6 on-wire is the preferred method of handling
1288: things.
1289:
1290: The first step to do so is to assign an IPv6-address to your ethernet. In the
1291: following example we will assume subnet `2` of the IPv6-net is used for the
1292: local ethernet and the MAC address of the ethernet interface is
1293: 12:34:56:78:9a:bc, i.e. your local gateway's ethernet interface's IP address
1294: will be 2002:3ee0:3972:2:1234:56ff:fe78:9abc. Assign this address to your
1295: ethernet interface, e.g.
1296:
1297: # ifconfig ne0 inet6 alias 2002:3ee0:3972:2:1234:56ff:fe78:9abc
1298:
1299: Here, `ne0` is an example for your ethernet card interface. This will most
1300: likely be different for your setup, depending on what kind of card is used.
1301:
1302: Next thing that needs to be ensured for setting up the router is that it will
1303: actually forward packets from the local 6to4 device to the ethernet device and
1304: back. To enable IPv6 packet forwarding, set `ip6mode=router` in NetBSD's
1305: `/etc/rc.conf`, which will result in the `net.inet6.ip6.forwarding` sysctl being
1306: set to `1`:
1307:
1308: # sysctl -w net.inet6.ip6.forwarding=1
1309:
1310: 
1311: **Enabling packet forwarding is needed for a 6to4 router**
1312:
1313: To setup router advertisement on BSD, the file `/etc/rtadvd.conf` needs to be
1314: checked. It allows configuration of many things, but usually the default config
1315: of not containing any data is ok. With that default, IPv6 addresses found on all
1316: of the router's network interfaces will be advertised.
1317:
1318: After checking the router advertisement configuration is correct and IPv6
1319: forwarding is turned on, the daemon handling it can be started. Under NetBSD, it
1320: is called `rtadvd`. Start it up either manually (for testing it the first time)
1321: or via the system's startup scripts, and see all your local nodes automagically
1322: configure the advertised subnet address in addition to their already-existing
1323: link local address.
1324:
1325: # rtadvd
1326:
1327: ### Quickstart using pkgsrc/net/hf6to4
1328:
1329: So far, we have described how 6to4 works and how to set it up manually. For an
1330: automated way to make everything happen e.g. when going online, the 'hf6to4'
1331: package is convenient. It will determine your IPv6 address from the IPv4 address
1332: you got assigned by your provider, then set things up that you are connected.
1333:
1334: Steps to setup the pkgsrc/net/hf6to4 package are:
1335:
1336: 1. Install the package either by compiling it from pkgsrc, or by `pkg_add`'ing
1337: the 6to4-1.2 package.
1338:
1339: # cd /usr/pkgsrc/net/hf6to4
1340: # make install
1341:
1342: 2. Make sure you have the
1343: [stf(4)](http://netbsd.gw.com/cgi-bin/man-cgi?stf+4+NetBSD-5.0.1+i386)
1344: pseudo-device in your kernel, see above.
1345:
1346: 3. Configure the 'hf6to4' package. First, copy
1347: `/usr/pkg/share/examples/hf6to4/hf6to4.conf` to `/usr/pkg/etc/hf6to4.conf`,
1348: then adjust the variables. Note that the file is in /bin/sh syntax.
1349:
1350: # cd /usr/pkg/etc
1351: # cp ../share/examples/hf6to4/hf6to4.conf hf6to4.conf
1352: # vi hf6to4.conf
1353:
1354: Please see the
1355: [hf6to4(8)](http://netbsd.gw.com/cgi-bin/man-cgi?hf6to4+8+NetBSD-5.0.1+i386)
1356: manpage for an explanation of all the variables you can set in
1357: `hf6to4.conf`. If you have dialup IP via PPP, and don't want to run Router
1358: Advertizing for other IPv6 machines on your home or office network, you
1359: don't need to configure anything. If you want to setup Router Advertising,
1360: you need to set the `in_if` to the internal (ethernet) interface, e.g.
1361:
1362: $in_if="rtk0"; # Inside (ethernet) interface
1363:
1364: 4. Now dial up, then start the 6to4 command manually:
1365:
1366: # /usr/pkg/sbin/hf6to4 start
1367:
1368: 5. After that, you should be connected, use
1369: [ping6(8)](http://netbsd.gw.com/cgi-bin/man-cgi?ping6+8+NetBSD-5.0.1+i386): to
1370: see if everything works:
1371:
1372: # ping6 www.NetBSD.org
1373: PING6(56=40+8+8 bytes) 2002:d954:110b:1::1 --> 2001:4f8:4:7:2e0:81ff:fe52:9a6b
1374: 16 bytes from 2001:4f8:4:7:2e0:81ff:fe52:9a6b, icmp_seq=0 hlim=60 time=250.234 ms
1375: 16 bytes from 2001:4f8:4:7:2e0:81ff:fe52:9a6b, icmp_seq=1 hlim=60 time=255.652 ms
1376: 16 bytes from 2001:4f8:4:7:2e0:81ff:fe52:9a6b, icmp_seq=2 hlim=60 time=251.237 ms
1377: ^C
1378: --- www.NetBSD.org ping6 statistics ---
1379: 3 packets transmitted, 3 packets received, 0.0% packet loss
1380: round-trip min/avg/max/std-dev = 250.234/252.374/255.652/2.354 ms
1381:
1382: # traceroute6 www.NetBSD.org
1383: traceroute6 to www.NetBSD.org (2001:4f8:4:7:2e0:81ff:fe52:9a6b)
1384: from 2002:d954:110b:1::1, 64 hops max, 12 byte packets
1385: 1 2002:c25f:6cbf:1::1 66.31 ms 66.382 ms 69.062 ms
1386: 2 nr-erl1.6win.dfn.de 76.134 ms * 76.87 ms
1387: 3 nr-fra1.6win.dfn.de 76.371 ms 80.709 ms 79.482 ms
1388: 4 dfn.de6.de.6net.org 92.763 ms 90.863 ms 94.322 ms
1389: 5 de.nl6.nl.6net.org 116.115 ms 93.463 ms 96.331 ms
1390: 6 nl.uk6.uk.6net.org 103.347 ms 99.334 ms 100.803 ms
1391: 7 uk1.uk61.uk.6net.org 99.481 ms 100.421 ms 100.119 ms
1392: 8 2001:798:28:300::2 89.711 ms 90.435 ms 90.035 ms
1393: 9 ge-1-0-0-2.r20.londen03.uk.bb.verio.net 179.671 ms 185.141 ms 185.86 ms
1394: 10 p16-0-0-0.r81.nycmny01.us.bb.verio.net 177.067 ms 179.086 ms 178.05 ms
1395: 11 p16-1-1-3.r20.nycmny01.us.bb.verio.net 178.04 ms 179.727 ms 184.165 ms
1396: 12 p16-0-1-1.r20.mlpsca01.us.bb.verio.net 249.856 ms 247.476 ms 249.012 ms
1397: 13 p64-0-0-0.r21.snjsca04.us.bb.verio.net 239.691 ms 241.404 ms 240.998 ms
1398: 14 p64-0-0-0.r21.plalca01.us.bb.verio.net 247.541 ms 246.661 ms 246.359 ms
1399: 15 xe-0-2-0.r20.plalca01.us.bb.verio.net 240.987 ms 239.056 ms 241.251 ms
1400: 16 ge-6-1.a01.snfcca05.us.ra.verio.net 240.868 ms 241.29 ms 242.337 ms
1401: 17 fa-5-2.a01.snfcca05.us.ce.verio.net 249.477 ms 250.4 ms 256.035 ms
1402: 18 2001:4f8:4:7:2e0:81ff:fe52:9a6b 268.164 ms 252.97 ms 252.366 ms
1403:
1404: Please note that `traceroute6` shows the v6 hops only, any underlying
1405: tunnels are invisible and thus not displayed.
1406:
1407: 6. If this works, you can put the following lines into your `/etc/ppp/ip-up`
1408: script to run the command each time you go online:
1409:
1410: logger -p user.info -t ip-up Configuring 6to4 IPv6
1411: /usr/pkg/sbin/hf6to4 stop
1412: /usr/pkg/sbin/hf6to4 start
1413:
1414: 7. If you want to route IPv6 for your LAN, you can instruct `6to4.pl` to setup
1415: Router Advertising for you too:
1416:
1417: # /usr/pkg/sbin/hf6to4 rtadvd-start
1418:
1419: You can put that command into `/etc/ppp/ip-up` as well to make it permanent.
1420:
1421: 8. If you have changed `/etc/ppp/ip-up` to setup 6to4 automatically, you will
1422: most likely want to change `/etc/ppp/ip-down` too, to shut it down when you
1423: go offline. Here's what to put into `/etc/ppp/ip-down`:
1424:
1425: logger -p user.info -t ip-down Shutting down 6to4 IPv6
1426: /usr/pkg/sbin/hf6to4 rtadvd-stop
1427: /usr/pkg/sbin/hf6to4 stop
1428:
1429: ### Known 6to4 Relay Routers
1430:
1431: It is normally not necessary to pick a specific 6to4 relay router, but if
1432: necessary, you may find a list of known working routers at
1433: [http://www.kfu.com/\~nsayer/6to4/](http://www.kfu.com/~nsayer/6to4/). In tests,
1434: only 6to4.kfu.com and 6to4.ipv6.microsoft.com were found working. Cisco has one
1435: that requires registration, see
1436: [http://www.cisco.com/ipv6/](http://www.cisco.com/ipv6/).
1437:
1438: There's also an experimental 6to4 server located in Germany,
1439: 6to4.ipv6.fh-regensburg.de. This server runs under NetBSD 1.6 and was setup
1440: using the configuration steps described above. The whole configuration of the
1441: machine can be seen at
1442: [http://www.feyrer.de/IPv6/netstart.local](http://www.feyrer.de/IPv6/netstart.local).
1443:
1444: ### Tunneling 6to4 through an IPFilter firewall
1445:
1446: The 6to4 protocol encapsulates IPv6 packets in IPv4, and gives them their own IP
1447: type, which most firewalls block as unknown, as their payload type is directly
1448: `TCP`, `UDP` or `ICMP`. Usually, you want to setup your 6to4 gateway on the same
1449: machine that is directly connected to the (IPv4) internet, and which usually
1450: runs the firewall. For the case that you want to run your 6to4 gateway behind a
1451: firewall, you need to drill a hole into the firewall, to let 6to4 packets
1452: through. Here is how to do this!
1453:
1454: The example assumes that you use the `ppp0` interface on your firewall to
1455: connect to the Internet.
1456:
1457: Put the following lines into `/etc/ipf.conf` to allow your IPFilter firewall let
1458: all 6to4 packets pass (lines broken with `\` due to space restrictions; please
1459: put them lines continued that way all in one line):
1460:
1461: # Handle traffic by different rulesets
1462: block in quick on ppp0 all head 1
1463: block out quick on ppp0 all head 2
1464:
1465: ### Incoming packets:
1466: # allow some IPv4:
1467: pass in log quick on ppp0 proto tcp from any to any \
1468: port = www flags S keep state keep frags group 1
1469: pass in quick on ppp0 proto tcp from any to any \
1470: port = ssh keep state group 1
1471: pass in quick on ppp0 proto tcp from any to any \
1472: port = mail keep state group 1
1473: pass in log quick on ppp0 proto tcp from any to any \
1474: port = ftp keep state group 1
1475: pass in log quick on ppp0 proto tcp from any to any \
1476: port = ftp-data keep state group 1
1477: pass in log quick on ppp0 proto icmp from any to any group 1
1478: # allow all IPv6:
1479: pass in quick on ppp0 proto ipv6 from any to any group 1
1480: pass in log quick on ppp0 proto ipv6-route from any to any group 1
1481: pass in log quick on ppp0 proto ipv6-frag from any to any group 1
1482: pass in log quick on ppp0 proto ipv6-icmp from any to any group 1
1483: pass in log quick on ppp0 proto ipv6-nonxt from any to any group 1
1484: pass in log quick on ppp0 proto ipv6-opts from any to any group 1
1485: # block rest:
1486: blockin log quick on ppp0 all group 1
1487:
1488: ### Outgoing packets:
1489: # allow usual stuff:
1490: pass out quick on ppp0 proto tcp from any to any flags S \
1491: keep state keep frags group 2
1492: pass out quick on ppp0 proto udp from any to any \
1493: keep state keep frags group 2
1494: pass out quick on ppp0 proto icmp from any to any \
1495: keep state group 2
1496: # allow all IPv6:
1497: pass out quick on ppp0 proto ipv6 from any to any group 2
1498: pass out log quick on ppp0 proto ipv6-route from any to any group 2
1499: pass out log quick on ppp0 proto ipv6-frag from any to any group 2
1500: pass out log quick on ppp0 proto ipv6-icmp from any to any group 2
1501: pass out log quick on ppp0 proto ipv6-nonxt from any to any group 2
1502: pass out log quick on ppp0 proto ipv6-opts from any to any group 2
1503: # block rest:
1504: block out log quick on ppp0 all group 2
1505:
1506: Now any host on your network can send (the `out` rules) and receive (the `in`
1507: rules) v4-encapsulated IPv6 packets, allowing setup of any of them as a 6to4
1508: gateway. Of course you only want to do this on one host and use native IPv6
1509: between your hosts, and you may also want to enforce this with more restrictive
1510: rulesets, please see
1511: [ipf.conf(5)](http://netbsd.gw.com/cgi-bin/man-cgi?ipf.conf+5+NetBSD-5.0.1+i386)
1512: for more information on IPFilter rules.
1513:
1514: After your firewall lets pass encapsulated IPv6 packets, you may want to set up
1515: your 6to4 gateway to monitor the IPv6 traffic, or even restrict it. To do so,
1516: you need to setup IPFilter on your 6to4 gateway as well. For basic monitoring,
1517: enable `ipfilter=yes` in `/etc/rc.conf` and put the following into
1518: `/etc/ipf6.conf`:
1519:
1520: pass in log quick on stf0 from any to any
1521: pass out log quick on stf0 from any to any
1522:
1523: This logs all (IPv6) traffic going in and out of your `stf0` tunneling
1524: interface. You can add filter rules as well if needed.
1525:
1526: If you are more interested in traffic stats than a general overview of your
1527: network traffic, using MRTG in conjunction with the `net-snmp` package is
1528: recommended instead of analyzing IPFilter log files.
1529:
1530: ### Conclusion & Further Reading
1531:
1532: Compared to where IPv4 is today, IPv6 is still in its early steps. It is
1533: working, there are all sort of services and clients available, only the userbase
1534: is missing. It is hoped the information provided here helps people better
1535: understand what IPv6 is, and to start playing with it.
1536:
1537: A few links should be mentioned here for interested parties:
1538:
1539: * An example script to setup 6to4 on BSD based machines is available at
1540: <http://www.NetBSD.org/packages/net/hf6to4/>. The script determines your IPv6
1541: address and sets up 6to4 and (if wanted) router advertising. It was designed
1542: to work in dialup setups with changing IPv4 addresses.
1543:
1544: * Given that there isn't a standard for IPv6 in Linux land today, there are
1545: different setup instructions for most distributions. The setup of IPv6 on
1546: Debian GNU/Linux can be found at
1547: [http://people.debian.org/\~csmall/ipv6/setup.html](http://people.debian.org/~csmall/ipv6/setup.html).
1548:
1549: * The BSD Unix implementations have their own IPv6 documentation each,
1550: interesting URLs are <http://www.NetBSD.org/docs/network/ipv6/> for NetBSD,
1551: <http://www.freebsd.org/doc/en\_US.ISO8859-1/books/handbook/network-ipv6.html>
1552: for FreeBSD.
1553:
1554: * Projects working on implementing IPv6 protocol stacks for free Unix like
1555: operating systems are KAME for BSD and USAGI for Linux. Their web sites can
1556: be found at <http://www.kame.net/> and <http://www.linux-ipv6.org/>. A list
1557: of host and router implementations can be found at
1558: <http://playground.sun.com/pub/ipng/html/ipng-implementations.html>.
1559:
1560: * Besides the official RFC archive at <ftp://ftp.isi.edu/in-notes>, information
1561: on IPv6 can be found at several web sites. First and foremost, the 6Bone's
1562: web page at <http://www.6bone.net/> must be mentioned. 6Bone was started as
1563: the testbed for IPv6, and is now an important part of the IPv6-connected
1564: world. Other web pages that contain IPv6-related contents include
1565: <http://www.ipv6.org/>, <http://playground.sun.com/pub/ipng/html/> and
1566: <http://www.ipv6forum.com/>. Most of these sites carry further links - be
1567: sure to have a look!
1568:
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