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Flakey Server can't initiate a network connection. - Linux Setup, Configuration & Administration

Dear All This is driving me scatty, can't any one help? I have recently setup a new server running RH linux 7.3, which will, if it ever works be web server. The problem is that I cant connect to anything when the box initiates the request. For example if I ping localhost or the server's own IP address I get a reply, but anything else, including other boxes on the same subnet and the GW just give host unreachable. I can connect to the box with SSH no problem and view web pages on Apache which is running on it ...

  1. #1

    Default Flakey Server can't initiate a network connection.

    Dear All

    This is driving me scatty, can't any one help?

    I have recently setup a new server running RH linux 7.3, which will,
    if it ever works be web server.

    The problem is that I cant connect to anything when the box initiates
    the request. For example if I ping localhost or the server's own IP
    address I get a reply, but anything else, including other boxes on the
    same subnet and the GW just give host unreachable.

    I can connect to the box with SSH no problem and view web pages on
    Apache which is running on it (tho' as soon as the box uses a page
    that connects to another server ie mail etc it fails). I can also ping
    the box from any other PC and receive a reply. I can even connect via
    a windows box to the samba server running on the box.

    I'm sure the problem is with the network config, but can't see where
    the issue lies. I've included the outputs from ifconfig and netstat
    -rn below. Below those are the outputs from tcpdump when pinging
    between two servers. The first is where the ping was initiated by a
    server that is working fine and the second by the box that is
    "faulty". When the faulty box initiates the connection I only get
    repeated arp who-has messages.

    Can anyone suggest either what I can do to fix this or alternatively
    what can be done to further investigate this problem?

    Many thanks

    Paul

    ifconfig shows

    eth0 Link encap:Ethernet HWaddr 00:06:5B:F6:63:73
    inet addr:10.80.18.207 Bcast:10.80.23.255
    Mask:255.255.248.0
    UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
    RX packets:979979 errors:0 dropped:0 overruns:0 frame:0
    TX packets:9753 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:100
    RX bytes:116652031 (111.2 Mb) TX bytes:1651268 (1.5 Mb)
    Interrupt:17 Memory:feb60000-feb80000

    lo Link encap:Local Loopback
    inet addr:127.0.0.1 Mask:255.0.0.0
    UP LOOPBACK RUNNING MTU:16436 Metric:1
    RX packets:603 errors:0 dropped:0 overruns:0 frame:0
    TX packets:603 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:0
    RX bytes:66400 (64.8 Kb) TX bytes:66400 (64.8 Kb)

    and netstat -rn shows

    Kernel IP routing table
    Destination Gateway Genmask Flags MSS Window
    irtt Iface
    10.80.16.0 0.0.0.0 255.255.248.0 U 40 0 0 eth0
    127.0.0.0 0.0.0.0 255.0.0.0 U 40 0 0 lo
    0.0.0.0 10.80.16.1 0.0.0.0 UG 40 0 0 eth0

    -----------------------------------------------------------------------------
    tcpdump -e on ping from good machine to faulty machine

    this repeated over and over

    14:55:10.355955 0:50:4:67:ab:9b 0:6:5b:f6:63:73 ip 98: edm_bfhxx_fp002 
    14:55:10.355955 0:6:5b:f6:63:73 0:50:4:67:ab:9b ip 98: 10.80.18.207 >
    edm_bfhxx_fp002: icmp: echo reply


    ------------------------------------------------------------------------------
    tcpdump -e on ping from faulty machine to good machine

    this repeated over and over

    13:39:32.000864 0:6:5b:f6:63:73 Broadcast arp 42: arp who-has
    10.80.18.27 tell edm_bfhxx_wb005
    13:39:33.000793 0:6:5b:f6:63:73 Broadcast arp 42: arp who-has
    10.80.18.27 tell edm_bfhxx_wb005
    Paul Guest

  2. #2

    Default Flakey Server can't initiate a network connection.

    Dear All

    This is driving me scatty, can't any one help?

    I have recently setup a new server running RH linux 7.3, which will,
    if it ever works be web server.

    The problem is that I cant connect to anything when the box initiates
    the request. For example if I ping localhost or the server's own IP
    address I get a reply, but anything else, including other boxes on the
    same subnet and the GW just give host unreachable.

    I can connect to the box with SSH no problem and view web pages on
    Apache which is running on it (tho' as soon as the box uses a page
    that connects to another server ie mail etc it fails). I can also ping
    the box from any other PC and receive a reply. I can even connect via
    a windows box to the samba server running on the box.

    I'm sure the problem is with the network config, but can't see where
    the issue lies. I've included the outputs from ifconfig and netstat
    -rn below. Below those are the outputs from tcpdump when pinging
    between two servers. The first is where the ping was initiated by a
    server that is working fine and the second by the box that is
    "faulty". When the faulty box initiates the connection I only get
    repeated arp who-has messages.

    Can anyone suggest either what I can do to fix this or alternatively
    what can be done to further investigate this problem?

    Many thanks

    Paul

    ifconfig shows

    eth0 Link encap:Ethernet HWaddr 00:06:5B:F6:63:73
    inet addr:10.80.18.207 Bcast:10.80.23.255
    Mask:255.255.248.0
    UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
    RX packets:979979 errors:0 dropped:0 overruns:0 frame:0
    TX packets:9753 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:100
    RX bytes:116652031 (111.2 Mb) TX bytes:1651268 (1.5 Mb)
    Interrupt:17 Memory:feb60000-feb80000

    lo Link encap:Local Loopback
    inet addr:127.0.0.1 Mask:255.0.0.0
    UP LOOPBACK RUNNING MTU:16436 Metric:1
    RX packets:603 errors:0 dropped:0 overruns:0 frame:0
    TX packets:603 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:0
    RX bytes:66400 (64.8 Kb) TX bytes:66400 (64.8 Kb)

    and netstat -rn shows

    Kernel IP routing table
    Destination Gateway Genmask Flags MSS Window
    irtt Iface
    10.80.16.0 0.0.0.0 255.255.248.0 U 40 0 0 eth0
    127.0.0.0 0.0.0.0 255.0.0.0 U 40 0 0 lo
    0.0.0.0 10.80.16.1 0.0.0.0 UG 40 0 0 eth0

    -----------------------------------------------------------------------------
    tcpdump -e on ping from good machine to faulty machine

    this repeated over and over

    14:55:10.355955 0:50:4:67:ab:9b 0:6:5b:f6:63:73 ip 98: edm_bfhxx_fp002 
    14:55:10.355955 0:6:5b:f6:63:73 0:50:4:67:ab:9b ip 98: 10.80.18.207 >
    edm_bfhxx_fp002: icmp: echo reply


    ------------------------------------------------------------------------------
    tcpdump -e on ping from faulty machine to good machine

    this repeated over and over

    13:39:32.000864 0:6:5b:f6:63:73 Broadcast arp 42: arp who-has
    10.80.18.27 tell edm_bfhxx_wb005
    13:39:33.000793 0:6:5b:f6:63:73 Broadcast arp 42: arp who-has
    10.80.18.27 tell edm_bfhxx_wb005
    Paul Guest

  3. #3

    Default Re: Flakey Server can't initiate a network connection.

    In comp.os.linux.setup Paul Rogers <com> wrote: 

    Then you don't have a route to them, or the NIC does not work.
     

    The NIC works.
     
     

    Please use route -n.
     

    There you are. No route. Learn the difference between 16 and 18.
    ANd what's that mask for?
     

    Donnnnng.

    Peter
    Peter Guest

  4. #4

    Default Re: Flakey Server can't initiate a network connection.

    Paul Rogers wrote:
     

    Sounds like your gateway or netmask are wrong. Take a look in
    /etc/sysconfig/network to see what these are, or in
    /etc/sysconfig/network-scripts/ifcfg-eth* for multiple network ports.

     

    This part looks OK. The bitmapping from IP, Netmask, and broadcast all
    look good.
     

    This.... looks a little weird. Are you sure your gateway is 10.80.16.1?
    And is your upstream switch or router correctly configured to route the
    10.18.16.0/255.255.248.0 subnet for you?


    Nico Guest

  5. #5

    Default Re: Flakey Server can't initiate a network connection.

    Nico Kadel-Garcia <net> wrote in message news:<com>... 

    Peter/Nico

    Many thanks for the replies. It's a class A network that extends from
    10.80.16.0 to 10.80.23.255 hence the 255.255.248.0 mask. The router
    is indeed on 10.80.16.1 (THere are no typos in there). The same set
    up (with different individual IP addresses obviously) works fine on
    every other machine on the network. TCPDump's output suggests that for
    some reason the faulty machine cannot resolve the mac address of any
    machine when it initiates the connection.

    Can you suggest why this might be or how to investigate further?

    Thanks

    Paul
    Paul Guest

  6. #6

    Default Re: Flakey Server can't initiate a network connection.

    Paul Rogers wrote:
     
    >
    >
    > Peter/Nico
    >
    > Many thanks for the replies. It's a class A network that extends from
    > 10.80.16.0 to 10.80.23.255 hence the 255.255.248.0 mask. The router
    > is indeed on 10.80.16.1 (THere are no typos in there). The same set
    > up (with different individual IP addresses obviously) works fine on
    > every other machine on the network. TCPDump's output suggests that for
    > some reason the faulty machine cannot resolve the mac address of any
    > machine when it initiates the connection.
    >
    > Can you suggest why this might be or how to investigate further?
    >
    > Thanks[/ref]

    I don't have one off-hand. Can you try the machine on another port on
    the upstream router, one that is known to work and be configured correctly?

    Nico Guest

  7. #7

    Default Re: Flakey Server can't initiate a network connection.

    In comp.os.linux.setup Paul Rogers <com> wrote: 
    >
    > Many thanks for the replies. It's a class A network that extends from
    > 10.80.16.0 to 10.80.23.255 hence the 255.255.248.0 mask. The router
    > is indeed on 10.80.16.1 (THere are no typos in there). The same set
    > up (with different individual IP addresses obviously) works fine on
    > every other machine on the network. TCPDump's output suggests that for
    > some reason the faulty machine cannot resolve the mac address of any
    > machine when it initiates the connection.[/ref]

    Swap its NIC and see if it behaves better. Ditto cable. Physically move
    it to somewhere else and see if it gets better. Change its hub/switch
    [port].

    When you find out what changes its behavior, you'll know what it was.

    If the machine calls who-has and gets no reply, then the problem that
    those calls are not getting out to the net. If it gets replies and does
    not notice them, then IT has the problem in its brain, and I'd be
    checking its kernel.

    Peter
    Peter Guest

  8. #8

    Default Re: Flakey Server can't initiate a network connection.

    "Peter T. Breuer" <it.uc3m.es> wrote in message news:<it.uc3m.es>...
     

    Peter/Nico

    Again many thanks for the replies. I checked what traffic the
    receiver of the pings was getting while all this was going on and it
    was zilch, so as Peter suggests I think the faulty box isn't even
    broadcasting the requests onto the network. The box has two NIC's,
    one of which is disabled, I've tried both with the same results.
    I've also tried reinstalling the OS. NO joy.

    If I check the arp table after the ping I get that the ip address is
    unresolved. If a then ping the faulty box from the good box the arp
    table is updated with the mac address, and the faulty box can then
    initiate pings, until it is rebooted.

    I'll do what Nico suggests and try moving the box to another port on
    the switch, but I suspect it might be the NNIC "driver" that is faulty
    or the firmware.

    I'll let you know how I get on

    Many thanks

    Paul
    Paul Guest

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