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[IPV6-SSH/DNS} enable IPv6 link local adresses as listen-address %eth0
Closed, ResolvedPublicFEATURE REQUEST



It is not possible by VyOS-cli to adds ssh ipv6 services that it can be listening with link local addresses wildcard (ipv6-linklocal%ethX) , it should be work as service ping:

vyos@vyos:~$ ping fe80::5200:ff:fe08:0%eth0
PING fe80::5200:ff:fe08:0%eth0(fe80::5200:ff:fe08:0%eth0) 56 data bytes
64 bytes from fe80::5200:ff:fe08:0%eth0: icmp_seq=1 ttl=64 time=1.16 ms
64 bytes from fe80::5200:ff:fe08:0%eth0: icmp_seq=2 ttl=64 time=0.136 ms

but when we wants to add on VyOS-cli, it shows the following :

vyos@vyos# set service ssh listen-address fe80::5200:ff:fe08:0%eth0

  Invalid value
  Value validation failed
  Set failed

it should be support the wildcard %eth0 on DNS /ssh services . another comment regarding this behavior :


Difficulty level
Unknown (require assessment)
Why the issue appeared?
Will be filled on close
Is it a breaking change?
Perfectly compatible
Issue type
Bug (incorrect behavior)

Event Timeline


set service ssh disable-host-validation
set service ssh listen-address ''
set service ssh listen-address 'fe80::5054:ff:fe48:a0c6%eth0'

Chek service and listen-addresses:

vyos@r11-roll# cat /run/sshd/sshd_config | grep List
ListenAddress fe80::5054:ff:fe48:a0c6%eth0

vyos@r11-roll# sudo netstat -tulpn | grep ":22"
tcp        0      0*               LISTEN      11376/sshd: /usr/sb 
tcp6       0      0 fe80::5054:ff:fe48:a:22 :::*                    LISTEN      11376/sshd: /usr/sb 

Example DNS:

vyos@r11-roll# run show conf com | match dns
set service dns forwarding allow-from 'fe80::/64'
set service dns forwarding listen-address 'fe80::5054:ff:fe48:a0c6%eth0'
set service dns forwarding system
vyos@r11-roll# cat /run/powerdns/recursor.conf | grep "local"
Viacheslav changed the task status from Open to In progress.Tue, Dec 28, 4:02 PM

At the moment I am testing the patch with some common services and found a tiny issue inside the auto completion feature.

vyos@vyos# show service ssh listen-address <TAB>
Possible completions:


vyos@vyos# run show configuration commands |grep ssh
set service ssh listen-address 'fe80::abc2%eth0'

It looks like the "%eth0" got interpreted as some kind of format-string.

Maybe "is_addr_assigned" on "python/vyos/" needs to be patched too.
When I set "listen-address fe80::abc2%eth0" to service tftp-server then "is_addr_assigned" got called and run into an error:

vyos@vyos# show service tftp-server
 directory /tftp
+listen-address fe80::abc2%eth0 {
[ service tftp-server ]
VyOS had an issue completing a command.

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Report time:      2021-12-29 13:02:45
Image version:    VyOS 1.4-rolling-202112281820
Release train:    sagitta

Built by:
Built on:         Tue 28 Dec 2021 18:20 UTC
Build UUID:       b082ab9a-6426-4040-9e28-e45a67a2cbd6
Build commit ID:  4ccdaf58fc7b9b

Architecture:     x86_64
Boot via:         installed image
System type:      KVM guest

Hardware vendor:  QEMU
Hardware model:   Standard PC (i440FX + PIIX, 1996)
Hardware S/N:
Hardware UUID:    68aa120b-7a78-45b3-b6aa-9433b1a487c6

Traceback (most recent call last):
  File "/usr/libexec/vyos/conf_mode/", line 140, in <module>
  File "/usr/libexec/vyos/conf_mode/", line 70, in verify
    if not is_addr_assigned(address):
  File "/usr/lib/python3/dist-packages/vyos/", line 108, in is_addr_assigned
    tmp = is_intf_addr_assigned(intf, addr)
  File "/usr/lib/python3/dist-packages/vyos/", line 50, in is_intf_addr_assigned
    return _is_intf_addr_assigned(intf, addr)
  File "/usr/lib/python3/dist-packages/vyos/", line 84, in _is_intf_addr_assigned
    if not _are_same_ip(address, ip_addr):
  File "/usr/lib/python3/dist-packages/vyos/", line 44, in _are_same_ip
    return inet_pton(f_one, one) == inet_pton(f_one, two)
OSError: illegal IP address string passed to inet_pton

[[service tftp-server]] failed
Commit failed

Same thing with "service snmp".

This two services don't accept IPv6 at all:

service conntrack-sync
service dhcp-server

And Webproxy has another problem with IPv6 (T4116).

Other services are working fine:

set service https virtual-host listen-address fe80::abc2%eth0
set system ntp listen-address fe80::abc2%eth0
set service dns forwarding listen-address fe80::abc2%eth0
set service ssh listen-address fe80::abc2%eth0
Viacheslav changed the task status from In progress to Needs testing.Mon, Jan 3, 3:10 PM

@aha As I see tftp can't bind ipv6 link local address:

set service tftp-server listen-address fe80::5054:ff:fe48:a0c6

Jan 09 17:52:41 r11-roll in.tftpd[32395]: cannot bind to local IPv6 socket: Invalid argumen

Are you sure that it should work?

vyos@r11-roll# cat /etc/default/tftpd2
### Autogenerated by ###
DAEMON_ARGS="--listen --user tftp --address [fe80::5054:ff:fe48:a0c6]:69 -6  --secure /config/tftp"

@Viacheslav Yes, You're right.
in.tftpd got started (but only a few seconds).

I also tried it on ubuntu 20.10 with the same version of tftp-hpa (5.2) because the latest commit is more than 7 years ago.

tftp-hpa 5.2, with remap, with tcpwrappers

root@ubuntutest:~# in.tftpd -6 -l -a [fe80::1%eth0] -vvvv /
Jan  9 18:01:46 ubuntutest in.tftpd[643]: cannot resolve local IPv6 bind address: [fe80:(Temporary failure in name resolution)

root@ubuntutest:~# in.tftpd -6 -l -a [fe80::1] -vvvv /
Jan  9 18:02:04 ubuntutest in.tftpd[658]: cannot bind to local IPv6 socket: Invalid argument

I can try to ask H. Peter Anvin if there is a solution. But I do not expect an answer.
Most people may use inetd/xinetd and may not have such problems :/

Viacheslav moved this task from Need Triage to Finished on the VyOS 1.4 Sagitta board.