mailu_front_1: Error starting userland proxy: listen tcp [::]:995: bind: cannot assign requested address

[Jan-Bart]

Hi,

I'm getting this error when listening on both, ipv6 and ipv4 addresses:

mailu_front_1: Error starting userland proxy: listen tcp [::]:995: bind: cannot assign requested address

I know per #321 that you can fix this by removing either BIND_ADDRESS6 or BIND_ADDRESS4.
And indeed, that fixes the issues but is rather a workaround than a fix.

What's the proper way to deal with this issue?
I'm running docker-compose version 1.17 and do not use 0.0.0.0 as ipv4 address ( #537 )
Using notls or letsencrypt doesn't make any difference ( #378 )

Related issues but with workarounds:
#464
#422

[kaiyou]

The proper way is to set an actual IPv6 address instead of ::. Mailu is meant to be listening on a specific IP address, which is the address of your MX record.

[Jan-Bart]

But you can't use both IPv4 and IPv6?

I'm using an actual IP address for both IPv4 and IPv6.

[kaiyou]

You can use both as long as you specify an actual IP for each one. If you did, then I believe you just found a bug.

[Jan-Bart]

In that case: I think I found a bug :)

[kaiyou]

What is weird is that docker tries to listen to :: which should not happen if you properly set BIND_ADDRESS6. Could you share at least this part of your .env? (slightly change your IP if you do not wish to share it)

[Jan-Bart]

(IP is slightly changed)

# Address where listening ports should bind
BIND_ADDRESS4=00.00.137.241
BIND_ADDRESS6=3b00:4f9:c010:1f0::2


# Main mail domain

[muhlemmer]

I can reproduce this when using the <link> scoped ip6 address.

@Jan-Bart : Run the following, replacing eth0 to the interface you want to use:

[tim@mars ~]$ ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 5.189.138.127  netmask 255.255.255.0  broadcast 5.189.138.255
        inet6 2a02:c207:2019:6443::1  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::250:56ff:fe3c:b223  prefixlen 64  scopeid 0x20<link>
        ether 00:50:56:3c:b2:23  txqueuelen 1000  (Ethernet)
        RX packets 18935526  bytes 25326921818 (23.5 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 4657359  bytes 445449606 (424.8 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

There are 2 inet6 addresses specified. You need to use the one with the <global> scope. If you don't have a <global> scope, it means your DHCP server did not give your interface one or your network does not support ipv6.

[Jan-Bart]

That was indeed the issue. Thank you verry much @muhlemmer ! :)

[Techssh]

With ipv4, does it work with the IP address of the local interface? or public IP?