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Re: ssh communication issue

Larry Irwin wrote:
Our ssh connections work fine on all our servers when we connect via the local network. But, when we ssh from the internet, there are long pauses where i/o is not displayed/echoed to the screen on our Debian servers. We experience 10 to 30 second pauses after a screen or 2 of display on Debian Etch kernel 2.6.12, SSH-2.0-OpenSSH_4.2p1 Debian-5. We have same issue, with slightly shorter pauses, on a Debain Sarge kernel 2.4.18, OpenSSH_3.4p1 Debian 1:3.4p1-1.woody.3. We do not experience the problem on a SCO OS5 3.2v5.0.5 kernel, OpenSSH_2.2.0p1
Does anyone know what might me contributing to the screen IO issue?

You're not very clear about which portion of the session is slow.

Individual characters echoing back from the remote end after you're at a shell? The initial connection process?

Look for...

A slow network. (Latency across the Internet is not great for interactive keyboard sessions, in many cases.)

A slow DNS lookup or lack of /etc/hosts entries. (During the connection process, SSH looks up your remote machine's name via reverse DNS lookups. Are you coming from machines that don't have proper reverse DNS entries on the new Debian machines, whereas the old SCO machine has a proper reverse DNS entry?)

A slow machine.  (Are all these machines the same speed/quality?)

ssh -v will help you see what portion of the process is slow if it's during the connection process.

If it's after you're connected, see what the ping times between your server and your client are. That's the biggest factor in how "interactive" your keyboard will feel.


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