Unix Shell and SSH Timeouts
You may find that after a period of inactivity your connection to a unix machine (solaris or linux) disconnects automatically. Typically this time might be something like one hour.
There are 3 possible causes for such inactivity timeouts:
- The automatic logout timeout for the login shell on the unix machine. If this is the case you will receive a "auto-logout" message when the timeout occurs.
- An ssh inactivity timeout on either the server or the client.
- A TCP inactivity timeout enforced by a router.
In the first case you should receive single word message "auto-logout" immediately before the logout occurs.
In both the second and third cases you may receive a message similar to:
- Read from remote host myhost.com: Operation timed out
- Connection to myhost.com closed.
the connection may also just seem to hang, or the connection will return you to your client machines prompt.
Shell auto-logout Solution
The solution to the first case (the automatic logout timeout for the login shell) is to unset the autologout shell variable. To do this:
- On the machine you are connecting to edit the file ".cshrc" in your home directory.
- Add the line "unset autologout".
- The new setting will take effect in all new connections.
SSH or TCP Timeout Solution for MacOS or Linux
If you are connecting from a MacOS, Linux, or other unix based machine the solution to both the second and third cases (ssh timeout or tcp inactivity) is the same:
- On the machine you are connecting from go to the ".ssh" directory in your home directory.
- Edit the file "config" (this file may not already exist and you may need to create it).
- Add the following lines:
- TCPKeepAlive no
- The new settings will take effect in all new connections.
It may be necessary to adjust the value of ServerAliveInterval to a lower number, however too low a number may actually cause additional disconnects if the the connection is only temporarily down. Do not set this number to a value less than 60 (one minute).
SSH or TCP Timeout Solution for Windows
If you experience the SSH or TCP timeout problem from a Windows SSH client please contact us as there doesn't appear to be a way to alter these settings in the Windows client and further research will be required.