Re: [gentoo-user] Configure sshd to listen on specific interfaces?

[Michael Orlitzky]

On 2020-08-27 09:40, Grant Edwards wrote:
> I'm trying to figure out how to conifgure openssh sshd to listen on
> specific interface(s).  I know how to configure it to listen on a
> specific IP address, but what do you do when using DHCP and don't know
> what IP address is going to be assigned.
>
> I do _not_ want it to listen on 0.0.0.0.
>
> I want it to listen on 127.0.0.1 and on whatever IP addresses are
> assigned to two specified interfaces.
>

You could modify the OpenRC init script to figure out what IP addresses
belong to those interfaces beforehand. The grep/sed here is ugly and I'm
sure there's a better way to do it, but this proves it's possible.

#!/bin/sh

INTERFACES="lo enp3s0"
SSHD_OPTS=""

for iface in ${INTERFACES}; do
  for ip in $(ip addr show dev "${iface}" | \
              grep inet | \
              sed "s/ *inet \([0-9\.]*\).*/\1/g"); do
      SSHD_OPTS="${SSHD_OPTS} -o \"ListenAddress ${ip}\""
  done
done

echo "${SSHD_OPTS}"