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stolivar_88319's avatar
stolivar_88319
Icon for Nimbostratus rankNimbostratus
Feb 09, 2009

ssh disconnects after a few minutes of no activity

I have a LB virtual server setup with two pools, a primary and a backup pool. Each pool has only one server in it. our primary server is in the first pool and there are virtual servers to handle http https, ftp and ssh. All traffic seems to be good but ssh seems to kill the connection after two minutes of inactivity. The timeouts are all set to 15 minutes. I just can't figure out what the problem might be. Thoughts?

 

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  • JRahm's avatar
    JRahm
    Icon for Admin rankAdmin
    Feb 09, 2009
    which timers, specifically, were set? LTM and/or server? A tcpdump of the client and server networks will show where the timeout is occuring.
  • stolivar_88319's avatar
    stolivar_88319
    Icon for Nimbostratus rankNimbostratus
    Feb 09, 2009
    I have set the timeout on the health monitor, as well as created an iRule that keeps ssh open. Not sure where else in the F5 to look. This is clearly an F5 issue, because if I ssh directly to the box, my session will stay open as long as I want.

     

     

    Where else should I be looking at in the F5?
  • dennypayne's avatar
    dennypayne
    Icon for Employee rankEmployee
    Feb 09, 2009
    Health monitor timeout only controls when the service is marked down. You need to look in the tcp profile. If you are using the default tcp profile, the idle timeout is 300 seconds. I would create a new tcp profile with a longer idle timeout and assign that to your ssh virtual server.

     

     

    Denny
  • dennypayne's avatar
    dennypayne
    Icon for Employee rankEmployee
    Feb 09, 2009

    Posted By dennypayne on 02/09/2009 1:01 PM

     

    Health monitor timeout only controls when the service is marked down.

     

     

     

     

    Which, if you've set that to 15 minutes, means your health checking will be virtually useless. The default health check interval of 5 seconds with a 16 second timeout is generally a good balance between application availability and getting false failures.

     

     

    Denny