Fix ipv4-only for unbound

[feld]

It's possible to deploy a Chatmail relay server that misbehaves because it tries to deliver to mail servers that have an AAAA and just fails. We should control sysctls and guard any setting for Postfix/Dovecot in the templates that enable IPv6 functionality

edit: this is a rough placeholder issue as the reporter's GitHub account was banned and they need to make a new one. More information will be coming.

[link2xt]

It is currently opt-out, but there is a setting to disable it:

relay/chatmaild/src/chatmaild/ini/chatmail.ini.f

Lines 63 to 64 in 8f68672

	# if set to "True" IPv6 is disabled
	disable_ipv6 = False

[missytake]

I'd like to close this issue for now, we can re-open it if the original poster re-appears and gives more information. Personally, I'm sceptical to make IPv6 opt-in, and opt-out is already supported - so to keep this open we need more arguments. And if it was actually a problem with disable_ipv6 = True, we need more information what went wrong.

[ccclxxiii]

@missytake here is the core issue i see.

when unbound deploys by default it will listen on ipv4 and ipv6. the machine it was deployed to couldn't bind unbound to the interface since the expectation was to have ipv6 enabled. this caused the cmdeploy run to fail with a systemd journal entry noting it could not bind the interface.

as a patch i created /etc/unbound/unbound.conf.d/custom-interfaces.conf

as:

server:
    interface: 127.0.0.1
    do-ip6: no
    interface-automatic: no

sighup'd unbound, and then re-deployed and it worked.

it seems the case for disable_ipv6 = True has no effect on the unbound service whether True || False

as for postfix, i've deployed a new relay and it failed without changing mynetworks in /etc/postfix/main.cf

mynetworks = 127.0.0.0/8

py infra will overwrite this each time you perform a cmdeploy run so it may be something we consider with .j2 templating for postfix and unbound

likely a pr i can make if there's interest in fixing it.

cc: @feld

[adbenitez]

that was also my experience when deploying chatmail in a server that had IPv6 disabled by default (Contabo), even if I was providing the disable_ipv6=True in chatmail.ini this was still failing