How To Keep Inactive SSH Session From Disconnected

For those who are particular about network security will never compromise to allow telnet protocol as part of the remote access implementation.

Beside network protocol consideration, network security experts also suggest configuring network routers to drop or disconnect an idle connection.

That was the problem what my colleague encountered this morning. When his Putty initiated SSH connection from outskirt to servers at HQ over VPN connection, with a not-so-good dial-up networking, the VPN router consistently disconnect / drop the SSH session whenever the idle threshold triggered.

However, some of the client software might able to overcome the restriction. For example, the Putty (wonderful Windows SSH client) offers keepalive option to get rid of “VPN router disconnects idle connection”!

Configure Putty keepalive option to get rid of VPN router auto disconnect idle or inactive SSH session.

[ Optional, only applicable if you want to save a SSH profile for convenient ] Click on the Session category tree menu, enter Host name or IP address of target host, select SSH protocol and gives it a meaningful profile name in Saved Sessions text box.
Click on the Connection category tree menu, enter a non-zero digit (indicates number of seconds) in Seconds between keepalives (0 to turn off) text box.
Go back to Session category tree menu and click the Save button.
From now onwards, whenever you load this SSH session profile and click Open button, the keepalive feature will be enabled to keep the inactive / idle SSH session from disconnected by VPN router (that enforce such rigid security practice).

So, if you’re using Putty as Windows SSH client and encounter problem of SSH disconnected after idle / inactive for some minutes, please try to configure the keepalive option.

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