bind_interface doesn't work, mosquitto only binds to localhost

[l29ah]

mosquitto-2.0.15 on Gentoo Lignux here. strace doesn't tell any hints on why doesn't it work. listener works but is unsuitable for dynamic IP addresses.

∞ grep -Ev '^#|^$' /etc/mosquitto/mosquitto.conf 
persistent_client_expiration 1y
bind_interface eth2
autosave_interval 1800
persistence true
persistence_file mosquitto.db
persistence_location /var/lib/mosquitto/
log_dest syslog
log_type information
allow_anonymous true

[nadav-bariks]

also having problem with bind_interface
mosquitto-2.0.15 on ubuntu 20.04

running mosquitto from command using sudo

mosquitto.config is:

listener  8882
bind_interface enp3s0
protocol mqtt
allow_anonymous true

getting error:
1669877815: Error: Invalid argument

If bind_interface line is removed, it works OK

[nadav-bariks]

problem is with ipv6
strace shows

bind(5, {sa_family=AF_INET6, sin6_port=htons(8882), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "fe80::9490:96c4:9f56:d81c", &sin6_addr), sin6_scope_id=0}, 28) = -1 EINVAL (Invalid argument)
write(2, "1669878630: Error: Invalid argum"..., 361669878630: Error: Invalid argument
)

adding
socket_domain ipv4
solves the problem

documentation does not say that bind_interface only works on ipv4

[jediminer543]

Ok, to add to this, the issue appears to occur because adapters always possess a link local address, and linux will return EINVAL when attempting to do this, unless you specify additional information to make link local addresses work

Mosquitto should probably either reject link-local addresses, or should properly handle them, by pulling more data out of the ifaddrs struct