sshd Failing New Inbound Connections

[Aaron Poffenberger]

> On Mar 17, 2022, at 22:52, Damien Miller <djm at mindrot.org> wrote:
> 
> On Thu, 17 Mar 2022, Aaron Poffenberger wrote:
> 
>> I managed to lock myself out of my firewall today.
>> 
>> I disabled inet6 resolution by removing it from the `family` option in 
>> resolve.conf(5). After a while I noticed I couldn't make new inbound
>> connections using either ipv4 or ipv6. My client kept reporting:
>> 
>> "kex_exchange_identification: Connection closed by remote host"
>> 
>> On the server I found the following errors in /var/log/authlog:
>> 
>> "fatal: bad addr or host: ::1 (no address associated with name)"
>> 
>> Totally my fault for changing resolv.conf without enough thought, but 
>> perhaps sshd could disable the listener in such cases.
> 
> Well, we can't catch every misconfiguration that could result in
> sshd failing to accept connections, but I think we can fix this one :)

:)

> 
> sshd doesn't need to actually resolve the listenaddress directives in
> the reexec path, so skip it.

The fw is on -release. I'll setup a build environment this weekend and
test the patch.

Cheers!

--Aaron