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Greatings, This is my first post here, so.. Hello Everybody! I have a linux industrial computer with 2 NICs. They were both working Ok. One of them still is, but ...
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  1. #1
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    TCP traffic blocked


    Greatings,

    This is my first post here, so.. Hello Everybody!

    I have a linux industrial computer with 2 NICs.
    They were both working Ok.
    One of them still is, but the other has now a problem.

    It shows UDP and ICMP traffic (according to iptraf and it responds to pings).. But I can't use SSH and I saw that TCP traffic remains to 0 (according to iptraf). SSH still works with the other card.

    I'm assuming that it's not and hardware problem. All the leds seem to be normal.
    How can I find the problem?

    Thanxs in advance.

    Paulo.

  2. #2
    Linux Engineer Kloschüssel's Avatar
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    Howdie

    did you firewall yourself out of the box? Please post the output of:

    Code:
    %iptables -L
    If you're unsure, you could reduce the complexity of the problem by attaching a laptop to the "broken" NIC directly and try to ssh into the device. If it doesn't work, you know that it is a problem with the NIC or the software on the box. If it works it is a problem unrelated to the device.

    Cheers

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    Quote Originally Posted by Kloschüssel View Post
    Howdie

    did you firewall yourself out of the box? Please post the output of:

    Code:
    %iptables -L
    If you're unsure, you could reduce the complexity of the problem by attaching a laptop to the "broken" NIC directly and try to ssh into the device. If it doesn't work, you know that it is a problem with the NIC or the software on the box. If it works it is a problem unrelated to the device.

    Cheers
    Hello, Kloschüssel.
    Thank you very much for your answer.

    In this box there is no firewall enabled.
    I'll try to get an output log for iptables ASAP, which is not easy because I don't have permament access to it.

    As I said before, this box has 2 NICs. eth0 and eth1. eth0 is the one with problems.
    With eth1 I can connect using a laptop and SSH or WinSCP for instance.
    With eth0 I can send pings, and see UDP traffic (through iptraf diagnostics).. but no TCP.

    with eth0, ifconfig says it is UP. ethtool says "No link".
    I also found that at boot time, linux reports and error with eth0 regarding Checksum error.

    The logical explanation may be problems with the NIC, but I wanted to be sure.

    Thanks again.
    PJAR.

  4. #4
    Linux Engineer Kloschüssel's Avatar
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    Hi,

    if the box reports problems during boot, there are not neglectable chances of hardware malfunction. NIC's are cheap, you could try to replace it?

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    Quote Originally Posted by Kloschüssel View Post
    Hi,

    if the box reports problems during boot, there are not neglectable chances of hardware malfunction. NIC's are cheap, you could try to replace it?
    Hello.

    This is compactPCI box. The NICs are built-in and a nic card for this kind of box is not very cheap

    But I think I'll send it for repair. I think there's still a warranty for this box.

    Thank you.
    PJAR.

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