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4 Replies Latest reply: Dec 4, 2013 2:37 AM by clementeOTN RSS

Port open but not accessible from outside

975148 Newbie
Currently Being Moderated

I wanted to understand a certain behavior towards accessing a port on our RHEL 5X servers. The local IP of the server is 10.101.17.80 and when I do:

 

netstat -tupln | grep 1399

 

it shows that the port is open.

 

But, when I try to access from another machine with local IP 10.101.17.79 on the same VMware setup like:

 

telnet 10.101.17.80 1399

 

it says connection refused. There are no IPTABLES restriction also.

 

I hope my question is clear.

 

Please revert with the reply to my query.

 

Regards

  • 1. Re: Port open but not accessible from outside
    975148 Newbie
    Currently Being Moderated

    I came to know of an important conceptual thing in this that port just being open may not be enough for a telnet connection to be possible but that there has to be an application also listening on the port for telnet to connect.

     

    Making a humble request for a revert on this discussion.

  • 2. Re: Port open but not accessible from outside
    Dude! Guru
    Currently Being Moderated

    Telnet is an ancient client server protocol that was used many years ago to facilitate interactive text-oriented communication. It is obsolete, unsecure, ususually not part of any modern OS installation anymore, and certainly not the best network troubleshooting tool.


    Based on your problem description the issue might be the configuration or choice of the VMware network adapter for the virtual host or hosts, which may block communication by design or purpose. I suggest to check the documenation and limitation of the VMware network adapter in use. Anyway, questions specific to VMware that are not specific to Linux do not belong to this forum.

  • 3. Re: Port open but not accessible from outside
    975148 Newbie
    Currently Being Moderated

    Thanks for your reply. There is no firewall set up on RHEL as I checked the iptables. As per the link,

     

    https://en.wikipedia.org/wiki/Open_port

     

    there has to be an application listening on the port so that a telnet connection can be established.

     

    Requesting a revert.

  • 4. Re: Port open but not accessible from outside
    clementeOTN Explorer
    Currently Being Moderated

    Hi

     

    I think it is not alinux  network problem, it seems to be a vmware network problem

     

    The first step is check if it works locally . In the same machine do 

     

    telnet 10.101.17.80 

     

    If it works, the second step is  check it the iptables are rrunning

     

    /sbin/iptables -L

     

    the result will be something like

    [root@xxx [$/sbin/iptables -L

    Chain INPUT (policy ACCEPT)

    target     prot opt source               destination

     

     

    Chain FORWARD (policy ACCEPT)

    target     prot opt source               destination

     

     

    Chain OUTPUT (policy ACCEPT)

    target     prot opt source               destination

     

     

    If this two checks are correct, it will be a network problem, it could be local linux configuration, or the most probably vmware network configuration.

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