[gentoo-user] SSH UseDNS without IPv6?

[Florian Philipp <lists@binarywings.net>]

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Hi list!

I have an issue with SSH. It's a variation of the old "Set 'UseDNS no'
to avoid delays with faulty DNS records" theme.

Following setup:
1. I have a server with IPv6 compiled into the SSH daemon but no actual
IPv6 network interface.

2. The SSH client has no IPv6, neither compiled nor active.

3. The DNS server doesn't serve or support AAAA records. Apparently it
drops all such requests. All other records for IP and reverse lookup are
correct.

Now I'm experiencing the classic, very long delay when connecting to the
server via SSH because it does DNS lookups. When I look at wireshark
dumps, I see correctly served A and reverse lookups but the server also
insists on doing AAAA requests which time out.

I tried limiting the sshd "AddressFamily" to inet (aka IPv4) but this
didn't change anything. Is there another workaround or do I really have
to deactivate DNS lookups?

Thanks in advance!
Florian Philipp


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