PuTTY keepalive using Telnet

[Jim Williams]

When I set the seconds between keepalives under the Connection tab to prevent dropping the connection due to a 15 minute idle timeout on the firewall, I get a ^?g character string (octal 177 161) on the screen that is seen by the shell for each keepalive sent. This is the same string for the PuTTY Telnet Command - No Operation. I'm seeing this on HPUX-11.00,11.11. I don't see this on HPUX-10.20 or on SunOS 5.6 or 5.8. I tried copying my stty settings (stty -g) from a 10.20 system to a 11.00 system but it didn't help. What needs to be changed on 11.x to prevent this

[Elmar P. Kolkman · Accepted solution]

It seems HP has dropped the keepalive on the telnetd between 10.20 and the newer versions. So, to solve your problem, you need to replace the telnetd or you need to use another way to make sure the connection stays open. What I did in the past is starting top with a refresh rate of 1 minute (top -s 60) so my connection stays open when I don't use it.

But the best solution would be to stop using the telnet function of putty and start using ssh, which has a good keepalive functionality. Just install and configure openssh (available in binary form on the HP-UX site) and change your putty session settings to use ssh instead of telnet.