[Bug 424371] Re: Logins to OpenSSH server slow due to "UseDNS yes" config

[Brian]

I have this same issue, but on Fedora (yes, I realize this is an ubuntu
forum)

On Fedora, I have the issue on 5.2 openssh (FC10+) but not on 5.1 (FC9)

If a host is in the hosts file, it connects instantly.  If it needs to
check DNS, it takes 15 seconds or more to connect.  There's no slowness
to my DNS servers.  A tcpdump shows that when connecting from a host not
in the hosts file, it queries the DNS server multiple times at multiple
phases of the connection.  If I change UseDNS to no in the sshd_config,
it works fine.  However that disables other things, such as host
resolution for anchoring ssh keys to a "from=" address.  It can still be
done with IP addresses, but for my users who connect from dynamic IPs
such as from comcast, they can no longer lock their ssh keys down, which
is a problem.

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Logins to OpenSSH server slow due to "UseDNS yes" config
https://bugs.launchpad.net/bugs/424371
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