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    Diagnosing firewall problems

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    • Article Type: General
    • Product: Aleph
    • Product Version: 20

    Desired Outcome Goal:
    Diagnose whether GUI message "Failed to connect to host" is caused by network firewall problems.

    Procedure:
    It's possible that, though the pc_server is running on port 6nnn, this port is inaccessible because of network restrictions. To eliminate this possibility, do the following on your pc:

    start --> Run --> Type "telnet 10.1.235.14 6991" [where 10.1.235.14 is the server's address and 6991 is the pc_server port] in the Open box and click "OK".

    If the port is accessible, a Telnet window will open with a completely blank screen.

    If the port is *not* accessible, you will get the message "Connecting to 10.1.235.14", but after a few seconds this message -- and the Telnet window -- will disappear. In that case, check the firewall rules.

    Also, the internal connectivity of the server can be tested via the "telnet localhost nnnn" command.  For instance:

       aleph@libms1(a21_1):~/a21_1/alephm>telnet localhost 8991 
       Trying 127.0.0.1... 
       Connected to localhost. 
       Escape character is '^]'. 
     

    This (normal) result indicates that the internal connectivity is working and that the problem is external connectivity (load balancer, firewall, etc.)

     

    Category: System Management (500)

    • Article last edited: 29-Aug-2017