SSH failover - SSH

This is a discussion on SSH failover - SSH ; Assume we have one cluster, Cluster, including two computers Host_A: 192.168.6.4 Host_B: 192.168.6.5 Host_A and Host_B share a virutal IP address, 192.168.6.240. openssh has been installed in both machines and ssh works perfectly with Host_A, Host_B, and the Cluster: ssh ...

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Thread: SSH failover

  1. SSH failover

    Assume we have one cluster, Cluster, including two computers

    Host_A: 192.168.6.4
    Host_B: 192.168.6.5

    Host_A and Host_B share a virutal IP address, 192.168.6.240. openssh
    has been installed in both machines and ssh works perfectly with
    Host_A, Host_B, and the Cluster:

    ssh 192.168.6.4, works fine
    ssh 192.168.6.5, works fine
    ssh 192.168.6.240, works fine

    My question is how to failover a ssh connection. For example, if there
    is already a ssh connection to the cluster, ssh 192.168.6.240, and
    suppose the Host_A is the acitvate one who servers the connection. In
    case a failver over happens, the Host_B becomse active and take over
    the connection. Since Host_B doesn't have the state information such
    as in Host_A , the ssh connection to the cluster is reset and closed.
    You have to re-establish the ssh connection due to the failover.

    Is there any way to synchronize the two ssh server and make the ssh
    failover seemlessly (e.g., Host_B can take over the ssh connection
    without reset and close it)?

  2. Re: SSH failover

    >>>>> "elwoodwang" == elwoodwang writes:

    elwoodwang> Assume we have one cluster, Cluster, including two
    elwoodwang> computers Host_A: 192.168.6.4 Host_B: 192.168.6.5

    elwoodwang> Host_A and Host_B share a virutal IP address,
    elwoodwang> 192.168.6.240. openssh has been installed in both machines
    elwoodwang> and ssh works perfectly with Host_A, Host_B, and the
    elwoodwang> Cluster:

    elwoodwang> ssh 192.168.6.4, works fine ssh 192.168.6.5, works fine
    elwoodwang> ssh 192.168.6.240, works fine

    elwoodwang> My question is how to failover a ssh connection. For
    elwoodwang> example, if there is already a ssh connection to the
    elwoodwang> cluster, ssh 192.168.6.240, and suppose the Host_A is the
    elwoodwang> acitvate one who servers the connection. In case a failver
    elwoodwang> over happens, the Host_B becomse active and take over the
    elwoodwang> connection. Since Host_B doesn't have the state
    elwoodwang> information such as in Host_A , the ssh connection to the
    elwoodwang> cluster is reset and closed. You have to re-establish the
    elwoodwang> ssh connection due to the failover.

    elwoodwang> Is there any way to synchronize the two ssh server and
    elwoodwang> make the ssh failover seemlessly (e.g., Host_B can take
    elwoodwang> over the ssh connection without reset and close it)?

    No.

    --
    Richard Silverman
    res@qoxp.net


  3. Re: SSH failover

    elwoodwang@gmail.com wrote:
    > Assume we have one cluster, Cluster, including two computers
    >
    > Host_A: 192.168.6.4
    > Host_B: 192.168.6.5
    >
    > Host_A and Host_B share a virutal IP address, 192.168.6.240. openssh
    > has been installed in both machines and ssh works perfectly with
    > Host_A, Host_B, and the Cluster:
    >
    > ssh 192.168.6.4, works fine
    > ssh 192.168.6.5, works fine
    > ssh 192.168.6.240, works fine
    >
    > My question is how to failover a ssh connection. For example, if there
    > is already a ssh connection to the cluster, ssh 192.168.6.240, and
    > suppose the Host_A is the acitvate one who servers the connection. In
    > case a failver over happens, the Host_B becomse active and take over
    > the connection. Since Host_B doesn't have the state information such
    > as in Host_A , the ssh connection to the cluster is reset and closed.
    > You have to re-establish the ssh connection due to the failover.
    >
    > Is there any way to synchronize the two ssh server and make the ssh
    > failover seemlessly (e.g., Host_B can take over the ssh connection
    > without reset and close it)?


    The ability to do this would be a *MAJOR* security issue. I don't think you can do it.

    Any chance of using virtual servers on the far end to provide live migration from one server to another of the same active OS?

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