I’ve noticed that when I keep ssh sessions that I opened before untouched for some period of time (like 30 minutes) they become frozen and as a result I have to close ssh terminal and start a new connection. To prevent such situation I found several tips:
1) Start some utility updating the screen before leaving ssh session untouched. I usually use watch -n 1 ‘date’ that shows current date every second. Other simple way is to send icmp requests to some host, e.g. ping google.com.
2) Increase ssh session idle time by
echo “7200″ > /proc/sys/net/ipv4/tcp_keepalive_time
I’ve checked these tips with Fedora Core, CentOS, Debian and Ubuntu but I’m completely sure that it applicable also for other Linux distributions. First tip (ping) can be used in Unix also.