[SOLVED] Delay in network operations

[doragasu]

I have noticed there's a delay of several seconds in some network operations. For example, when I log in using SSH, there's a delay before I'm asked to input the password. Also when using proftpd there are delays every time I change a directory or try to transfer a file.

What is causing this delay? Is there a way to eliminate it?

[fredgarvin]

Look at /var/log/auth.log

Do you see entries in there about failed DNS lookups? Or failed reverse DNS or reverse IP lookups? I'm guessing that's the case.

If so, edit /etc/ssh/sshd_config and look for a line with "UseDNS" on it.

If it has a # in front of it, remove the #. (The # comments out the line).
Edit the line so it says:
UseDNS no

After saving your file, you'll have to restart the sshd process so your change takes effect. You'll probably want to have access to your console when you do this, in case your sshd doesn't restart cleanly...you won't have ssh access until it restarts!

To bounce the sshd process, just do this:
/etc/init.d/sshd restart

(Oh, you'll either have to be logged on as root or use sudo).

The pause with ftp MIGHT be a similar issue, but I can't help you out there as I don't use proftp.

-J

[orochi]

login via SSH and check your available memory and system performance by running:


free

top

ps aux

[doragasu]

Thanks a lot fredgarving, it was because of the DNS timeout. Now SSH works perfect.

I hope I can find the way to remove the delay in proftpd...

Also thanks orochi for your tip, but in this case, it isn't a resource problem.

[doragasu]

Finally I have found the way to remove delays in proftpd. I have added the next line to proftpd.conf in /etc/proftpd:

Code: Select all

UseReverseDNS off

Again, thanks a lot for help.

[orochi]

cat /etc/resolv.conf

is it empty?

[doragasu]

No, it's not empty. It has configured my primary and secondary DNS.