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Random network dies

Discussion in 'General Discussion' started by netlook, Jan 3, 2007.

  1. netlook

    netlook Well-Known Member
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    Hi,

    I have strange problem on fresh CentOS/cPanel server.

    From time to time network simply dies. I was SSH into server, then I noticed that I can not view any webpage from it.

    I did netstat -n but it only show somethink like this:

    Code:
    Active UNIX domain sockets (w/o servers)
    Proto RefCnt Flags       Type       State         I-Node Path
    unix  13     [ ]         DGRAM                    6272   /dev/log
    unix  2      [ ]         DGRAM                    11091  @/var/run/hal/hotplug_socket
    unix  2      [ ]         DGRAM                    3466   @udevd
    unix  2      [ ]         DGRAM                    137333
    unix  2      [ ]         DGRAM                    130898
    unix  2      [ ]         STREAM     CONNECTED     123293
    unix  3      [ ]         STREAM     CONNECTED     11090  /var/run/dbus/system_bus_socket
    unix  3      [ ]         STREAM     CONNECTED     11089
    unix  3      [ ]         STREAM     CONNECTED     11013
    unix  3      [ ]         STREAM     CONNECTED     11012
    unix  2      [ ]         DGRAM                    10842
    unix  2      [ ]         DGRAM                    9749
    unix  2      [ ]         DGRAM                    8360
    unix  2      [ ]         DGRAM                    8343
    unix  2      [ ]         DGRAM                    8320
    unix  2      [ ]         DGRAM                    8301
    unix  2      [ ]         DGRAM                    8079
    unix  2      [ ]         DGRAM                    6484
    unix  2      [ ]         DGRAM                    6353
    unix  2      [ ]         DGRAM                    6280
    Then I did:

    service network restart

    but it did not help. I need to reboot server.

    What it could be? Is this a problem with ifcfg-eth0 - I have somethink like this on problematic server:

    Code:
    DEVICE=eth0
    BOOTPROTO=dhcp
    HWADDR=00:13:D3:E4:EE:ED
    ONBOOT=yes
    TYPE=Ethernet
    When I start my server I get this in /var/log/messages:

    Code:
    network: Setting network parameters:  succeeded
    network: Bringing up loopback interface:  succeeded
    ifup:
    ifup: Determining IP information for eth0...
    dhclient: DHCPREQUEST on eth0 to 255.255.255.255 port 67
    dhclient: DHCPACK from [MY_MAIN_IP]
    NET: /sbin/dhclient-script : updated /etc/resolv.conf
    dhclient: bound to [MY_MAIN_IP] -- renewal in 70990 seconds.
    ifup:  done.
    NET: /etc/sysconfig/network-scripts/ifup-post : updated /etc/resolv.conf
    network: Bringing up interface eth0:  succeeded
    filelimits: Increasing file system limits succeeded
    ipaliases: Bringing up eth0:1 succeeded
    ipaliases: Routing 88.198.109.138 succeeded
    ipaliases: Bringing up eth0:2 succeeded
    ipaliases: Routing 88.198.109.139 succeeded
    ipaliases: Bringing up eth0:3 succeeded
    ipaliases: Routing 88.198.109.140 succeeded
    ipaliases: Bringing up eth0:4 succeeded
    ipaliases: Routing 88.198.109.141 succeeded
    ipaliases: Bringing up eth0:5 succeeded
    ipaliases: Routing 88.198.109.142 succeeded
    Can anyone help me with this?
     
    #1 netlook, Jan 3, 2007
    Last edited: Jan 4, 2007
  2. chirpy

    chirpy Well-Known Member

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    Go on, have a guess
    Is it only apache that you have problems accessing or the whole server? IF it's just apache then you could be hitting MaxClients (check the error_log), if it's everything, check the output of ifconfig and see if there are any errors logged against the NIC. If there are it could be a faulty NIC/cable/connection or local network problems.
     
  3. jsilvestre

    jsilvestre Member

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    Problem with network

    Dear netlook,

    did you have eth0 with dhcp?
     
  4. chirpy

    chirpy Well-Known Member

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    That output looks fine. Are you able to SSH into the server when this happens or are you using a remote console? If the latter, and you shutdown iptables (APF) can you ping an external IP address from the server? If you can't then it would suggest network problems to me.
     
  5. netlook

    netlook Well-Known Member
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    Hi Chirpy!

    Thanks for reply.

    This is output of my *ifconfig*:

    Code:
    eth0      Link encap:Ethernet  HWaddr 00:13:D3:E4:EE:ED
              inet addr:[MAIN-IP-ADDRESS]  Bcast:[MAIN-IP-ADDRESS]  Mask:255.255.255.224
              inet6 addr: fe80::213:d3ff:fee4:eeed/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:1743494 errors:0 dropped:0 overruns:0 frame:0
              TX packets:1149144 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000
              RX bytes:1861687602 (1.7 GiB)  TX bytes:530993292 (506.3 MiB)
              Interrupt:177 Base address:0x6000
    
    eth0:1    Link encap:Ethernet  HWaddr 00:13:D3:E4:EE:ED
              inet addr:[ADDITIONAL-IP-1]  Bcast:[ADDITIONAL-IP-LAST]  Mask:255.255.255.248
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              Interrupt:177 Base address:0x6000
    
    eth0:2    Link encap:Ethernet  HWaddr 00:13:D3:E4:EE:ED
              inet addr:[ADDITIONAL-IP-2]  Bcast:[ADDITIONAL-IP-LAST]  Mask:255.255.255.248
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              Interrupt:177 Base address:0x6000
    
    eth0:3    Link encap:Ethernet  HWaddr 00:13:D3:E4:EE:ED
              inet addr:[ADDITIONAL-IP-3]  Bcast:[ADDITIONAL-IP-LAST]  Mask:255.255.255.248
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              Interrupt:177 Base address:0x6000
    
    eth0:4    Link encap:Ethernet  HWaddr 00:13:D3:E4:EE:ED
              inet addr:[ADDITIONAL-IP-4]  Bcast:[ADDITIONAL-IP-LAST]  Mask:255.255.255.248
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              Interrupt:177 Base address:0x6000
    
    eth0:5    Link encap:Ethernet  HWaddr 00:13:D3:E4:EE:ED
              inet addr:[ADDITIONAL-IP-5]  Bcast:[ADDITIONAL-IP-LAST] Mask:255.255.255.248
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              Interrupt:177 Base address:0x6000
    
    lo        Link encap:Local Loopback
              inet addr:127.0.0.1  Mask:255.0.0.0
              inet6 addr: ::1/128 Scope:Host
              UP LOOPBACK RUNNING  MTU:16436  Metric:1
              RX packets:7313 errors:0 dropped:0 overruns:0 frame:0
              TX packets:7313 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:0
              RX bytes:2433235 (2.3 MiB)  TX bytes:2433235 (2.3 MiB)
    It is not only Apache, it is also POP3 or SMTP, I can't access cPanel too. I tried to shutdown APF/restart APF during problems, but it did not help.
     
  6. netlook

    netlook Well-Known Member
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    Hmm.. I have static IP addresses. When I was installing CentOS on this server I choose to get network via dhcp, but I'm not sure it is proper.
     
  7. netlook

    netlook Well-Known Member
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    It happend and I was ssh into the server during the problems (I logged before it happen). I was able to ping external IPs from the server but I cant access any service on the server from 2 different internet connections.
     
  8. jsilvestre

    jsilvestre Member

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    Problem with network

    Try use netconfig to reconfigure IP address again.
     
  9. AlexandreVeezon

    AlexandreVeezon Well-Known Member

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    Hi!
    The same happen with one of my machines.
    But in my case, the network dies just when the link goes down. Everytime we need to restart the link, ifconfig downs other IPs, remaining up only the main IP address.. So i have to up all the IPs again.. ifconfig eth0:1, eth0:2, eth0:3...
    Pretty strange :confused:

    I'm searching for details in logs you have said in this thread...
     
  10. AlexandreVeezon

    AlexandreVeezon Well-Known Member

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    Well

    I see one diference between 2 machines:
    In problematic one, I have NetworkManager on in chkconfig.
    In good one, the NetworkManager is off.
    It could be my problem?

    Look at this:

    Problematic Machine
    Code:
    root@bad [/var/log]# chkconfig --list | grep -i net
    NetworkManager  0:off     1:off     2:off     3:on      4:off     5:off     6:off
    netplugd        0:off     1:off     2:off     3:off     4:off     5:off     6:off
    network         0:off     1:off     2:on      3:on      4:on      5:on      6:off
    netdump         0:off     1:off     2:off     3:off     4:off     5:off     6:off
    netfs           0:off     1:off     2:off     3:on      4:on      5:on      6:off
    xinetd          0:off     1:off     2:off     3:on      4:on      5:on      6:off
    servces based on xinetd:
            krb5-telnet:    off
    
    Good Machine
    Code:
    root@good [/]# chkconfig --list | grep -i net
    NetworkManager  0:off     1:off     2:off     3:off     4:off     5:off     6:off
    netplugd        0:off     1:off     2:off     3:off     4:off     5:off     6:off
    network         0:off     1:off     2:on      3:on      4:on      5:on      6:off
    netdump         0:off     1:off     2:off     3:off     4:off     5:off     6:off
    netfs           0:off     1:off     2:off     3:on      4:on      5:on      6:off
    xinetd          0:off     1:off     2:off     3:on      4:on      5:on      6:off
    services based on xinetd:
            krb5-telnet:    off
    
    In additional, I run a test. I first unplugged the network cable from machine and plugged again. When the cable was off, all IPs goes down (except main IP). When the cable was put again, the IPs was still down, so I has to run service ipaliases restart. See the log:
    Code:
    Jun  5 10:25:37 server kernel: eth0: link down
    Jun  5 10:25:40 server NetworkManager: AUTO: Best wired device = (null)
    Jun  5 10:25:40 server NetworkManager: AUTO: Best wireless device = (null)  (null)
    Jun  5 10:25:40 server NetworkManager:     SWITCH: best device changed
    Jun  5 10:25:46 server kernel: eth0: link up, 100Mbps, full-duplex, lpa 0x41E1
    Jun  5 10:25:50 server NetworkManager: AUTO: Best wired device = eth0
    Jun  5 10:25:50 server NetworkManager: AUTO: Best wireless device = (null)  (null)
    Jun  5 10:25:50 server NetworkManager:     SWITCH: best device changed
    Jun  5 10:25:50 server NetworkManager: nm_state_modification_monitor(): beginning activation for device 'eth0'
    Jun  5 10:25:51 server named[3059]: client 72.30.58.113#54537: error sending response: network unreachable
    Jun  5 10:25:52 server named[3059]: client 72.30.58.113#53868: error sending response: network unreachable
    Jun  5 10:25:53 server NetworkManager: nm_state_modification_monitor() activated device eth0
    Jun  5 10:26:19 server ifconfig: SIOCSIFFLAGS: Unable to access required address
    Jun  5 10:26:19 server ipaliases: Shutting down eth0:1 failed
    Jun  5 10:26:19 server route: SIOCDELRT: Device does not exists
    Jun  5 10:26:19 server ipaliases: UnRouting 201.47.86.17 failed
    Jun  5 10:26:19 server ifconfig: SIOCSIFFLAGS: Unable to access required address
    Jun  5 10:26:19 server ipaliases: Shutting down eth0:2 failed
    Jun  5 10:26:19 server route: SIOCDELRT: Device does not exists
    Jun  5 10:26:19 server ipaliases: UnRouting 201.47.86.18 failed
    Jun  5 10:26:19 server ifconfig: SIOCSIFFLAGS: Unable to access required address
    Jun  5 10:26:19 server ipaliases: Shutting down eth0:3 failed
    Jun  5 10:26:19 server route: SIOCDELRT: Device does not exists
    Jun  5 10:26:19 server ipaliases: UnRouting 201.47.86.19 failed
    Jun  5 10:26:19 server ifconfig: SIOCSIFFLAGS: Unable to access required address
    Jun  5 10:26:20 server ipaliases: Shutting down eth0:4 failed
    Jun  5 10:26:21 server route: SIOCDELRT: Device does not exists
    Jun  5 10:26:23 server ipaliases: UnRouting 201.47.86.20 failed
    Jun  5 10:26:25 server ifconfig: SIOCSIFFLAGS: Unable to access required address
    Jun  5 10:26:25 server ipaliases: Shutting down eth0:5 failed
    Jun  5 10:26:25 server route: SIOCDELRT: Device does not exists
    Jun  5 10:26:26 server ipaliases: UnRouting 201.47.86.21 failed
    Jun  5 10:26:27 server ifconfig: SIOCGIFADDR: Unable to access required address
    Jun  5 10:26:27 server ifconfig: SIOCSIFBROADCAST: Unable to access required address
    Jun  5 10:26:28 server ifconfig: SIOCSIFBRDADDR: Unable to access required address
    Jun  5 10:26:28 server ifconfig: SIOCSIFFLAGS: Unable to access required address
    Jun  5 10:26:28 server ipaliases: Bringing up eth0:1 failed
    Jun  5 10:26:30 server route: SIOCADDRT: Device does not exists
    Jun  5 10:26:30 server ipaliases: Routing 201.47.86.17 failed
    Jun  5 10:26:30 server ipaliases: Bringing up eth0:2 succeeded
    Jun  5 10:26:30 server ipaliases: Routing 201.47.86.18 succeeded
    Jun  5 10:26:30 server ipaliases: Bringing up eth0:3 succeeded
    Jun  5 10:26:30 server ipaliases: Routing 201.47.86.19 succeeded
    Jun  5 10:26:31 server ipaliases: Bringing up eth0:4 succeeded
    Jun  5 10:26:31 server ipaliases: Routing 201.47.86.20 succeeded
    Jun  5 10:26:31 server ipaliases: Bringing up eth0:5 succeeded
    Jun  5 10:26:32 server ipaliases: Routing 201.47.86.21 succeeded
    
     
    #10 AlexandreVeezon, Jun 5, 2007
    Last edited: Jun 5, 2007
  11. AlexandreVeezon

    AlexandreVeezon Well-Known Member

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    Hi

    Sorry to bother you, but nobody knows what is the NetworkManager in my issue?
    I don't know if I can turn this off, what to install..
    Any help will be appreciated.

    Thank you guys
     
  12. AndyReed

    AndyReed Well-Known Member
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    I suggest you contact your host or your network provider and ask them to test your VLan or VPN. If no problem found, it might be a hardware problem and you might want to replace your server ethernet card.
     
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