There are a lot of questions about SSH connections being delayed, which usually can be fixed by disabling the DNS lookups. Unfortunately this doesn't seem to be my problem.
Our development server is accessed via SSH and Samba. When opening a connection to the server (either SSH or Samba) it takes a very long time. Accessing a Samba share via Windows is basically impossible because there is a timeout. Using smbclient works, but takes ages. When opening a SSH connection I get immediately prompted for the password and after hitting Enter the terminal instantly shows the MOTD. Afterwards it takes about a minute for the prompt to appear.
I watched the load of the server while connecting via SSH and Samba and could not find anything out of order. There is nothing out of the ordinary running and hogging up memory and CPU or something. I have no clue where this delay might come from. I already tried
UseDNS no in sshd_config and
proxy_dns = no in smb.conf, but to no avail.
Any idea about what might cause this would be greatly appreciated!
Update: I'm sorry to say so, but I have been away for some weeks now and in the meantime the servers in question have been replaced by other newer systems which so far didn't present the same problems. Unfortunately this leaves me with no possibility to check any of the suggestions made here, but I'm grateful for your help nonetheless!