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Hi I am somewhat of a novice in UNIX and am looking for some guidance. I installed CentOS 5.8 on a Dell Server in a DMZ and assigned an ip ...
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  1. #1
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    Bridging Question


    Hi

    I am somewhat of a novice in UNIX and am looking for some guidance.

    I installed CentOS 5.8 on a Dell Server in a DMZ and assigned an ip address to the system.

    From my desk PC, not in the DMZ, I am able to SSH to the Dell Server.

    I set up Bridging according to the instructions I found on-line.
    Bridging appears to be configured as expected (no errors during the activation).

    The ifconfig show the bridge as active as does the brctl show command.

    I issued these from the console connected to the server.

    However, once the network is up, I can no longer SSH to the Serve from my desk PC.

    I try a ping to the server and get no response.

    If I go to a PC in the DMZ, I am able to ping the server.

    I have iptables set to allow all.

    Do I need to add something to modify something on CentOS for bridging to allow me to SSH to the Dell Server?

    Thanks

  2. #2
    Linux Guru Lazydog's Avatar
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    Check the firewall settings. You should find that they are pointing to eth0 where you need them to point to the br0 interface.

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    Robert

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    Thanks Robert,

    I assume this is in iptables ..

    Can you provide the cmds that allow me to see if the firewall is pointing to eth0

    and

    the command to point them to br0

    thanks

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    I turned off the firewall on CentOS and still cannot access the server from outside the DMZ.

  6. #5
    Linux Guru Lazydog's Avatar
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    Why are you setting up a bridge on this server?

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    Robert

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    I am installing KVM and the install instructions list it as required..

    "set up a network bridge on the server so that virtual machines can be accessed from other hosts.."

  8. #7
    Linux Guru Lazydog's Avatar
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    So what is the output from the follwoing command;

    Code:
    ifconfig

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    Robert

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    see attached,,,
    Attached Images Attached Images

  10. #9
    Linux Guru Lazydog's Avatar
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    Wait. you are saying you cannot access the server from outside the DMZ. What other firewalls are in place? Normally there is one for the DMZ and this one might be stopping SSH to the server. I was thinking you were trying to SSH into the VM but after re-reading your posts it sounds like you cannot connect to the server at all from anywhere except the DMZ. In this case there is a firewall and that is stopping you from accessing the DMZ.

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    Robert

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    I checked this out prior to posting the first question...out IT dept says that traffic is passing through the firewall of the DMZ

    the strange thing this is,,,I can ssh and ping to the server with bridging off..

    As soon as I enable the bridging, I can no longer ping or ssh to the server..

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