ssh is slow to give me a prompt
On Sun, 2009-03-08 at 16:06 -0700, Daevid Vincent wrote:
> When I ssh to my server (192.168.1.100) or my notebook
> (192.168.1.190) which is on my local NAT'ted 1GB LAN, it can take
> several seconds to get my prompt on either one. Both are Ubuntu 8.10.
> This doesn't seem normal. We run Ubuntu servers at work, and they're
> in a huge network and I can ssh to them very quickly. I've tried from
> various computers and they all exhibit this behaviour when connecting
> to the server or my notebook. Even connecting to each other is slow.
> Is there some PAM setting or sshd_config that I need to enable/disable
> to speed this up? They do go through a 1GB switch DLink router to each
> other, but I don't see how that would be the issue.
Might be a slow DNS resolver. sshd sets UseDNS to "yes" which requires
the server to check that the client's host name really maps to the
client's IP address. This requires reverse DNS to be working properly.
Many home networks do not set up reverse resolution properly. I believe
the code tries a reverse lookup and if no response is received lets the
connection proceed. It could be some other issues, but try setting this
flag to "no" and see if it resolves the delay issue.
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