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Hi All, I've got a machine with two IPs (haven't seen this before). Working with ops to get the machine re-ip'd and now if you ssh to xxx.xxx.xxx.1 or xxx.xxx.xxx.2 ...
  1. 06-12-2010 #1
    Triton46
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    RE-IP Machine

    Hi All,

    I've got a machine with two IPs (haven't seen this before). Working with ops to get the machine re-ip'd and now if you ssh to xxx.xxx.xxx.1 or xxx.xxx.xxx.2 they both log into the same machine.

    I need to correct this issue to install my app, where can I start looking (ops are out for the weekend)?

    ifconfig shows the IP I want on eth4 (network is configured as eth4 and lo). All others are down on this machine. Route -n shows the proper IP in the table.
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  2. 06-12-2010 #2
    Irithori
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    Some points to consider, from the top of my head:
    • Maybe ops had a reason to configure 2 IPs? I would clarify that before breaking something unintentionally
    • More than 1 IP per interface is nothing special, so the question is rather:
    • What makes your app break in such an environment?
    • Do you have a way to access that machine *other* than ssh to these two IPs?
      Re-configuring network alyways has a chance to lock you out. Happens to the best of us
      By other ways I mean: Remote Management, Remote Hands or access to the local console.


    If you are sure, you want to continue:
    These are your friends:
    Code:
    ifconfig
route
ifup
ifdown
    Also it is a good idea to inform ops on all changes.
    You must always face the curtain with a bow.
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  3. 06-12-2010 #3
    Triton46
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    Thanks for the fast reply! I've been working with ops on Friday, the two IPs are a mistake in this case. The app is a product I work on (MPP DB) that requires single IP per node.

    I can access via iLO if the ssh breaks.

    ifconfig and route look good, but where do I look to see where this other IP is sourced?
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  4. 06-12-2010 #4
    Irithori
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    Could you paste the output of these?
    Code:
    ip link show
ifconfig -a
route -n

Maybe:
traceroute <otherIP>
    You must always face the curtain with a bow.
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  5. 06-12-2010 #5
    Triton46
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    I mispoke on this node, it is using eth5 not eth4: (I want to use xxx.xxx.xxx.102 not xxx.xxx.xxx.101). As a novice, what I see is that eth5 and eth2 are active, however I have eth2 down on ifconfig but it looks from this to still be active (is that right?)

    Code:
    route#ip link show

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 18:a9:05:68:3c:66 brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 18:a9:05:68:3c:68 brd ff:ff:ff:ff:ff:ff
4: eth2: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
    link/ether 18:a9:05:68:3c:62 brd ff:ff:ff:ff:ff:ff
5: eth3: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 18:a9:05:68:3c:64 brd ff:ff:ff:ff:ff:ff
6: eth4: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 00:1b:21:17:7b:f5 brd ff:ff:ff:ff:ff:ff
7: eth5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:1b:21:17:7b:f4 brd ff:ff:ff:ff:ff:ff



root# ifconfig -a
eth0      Link encap:Ethernet  HWaddr 18:a9:05:68:3c:66
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:40 Memory:f6000000-f6012700

eth1      Link encap:Ethernet  HWaddr 18:a9:05:68:3c:68
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:39 Memory:f4000000-f4012700

eth2      Link encap:Ethernet  HWaddr 18:a9:05:68:3c:62
          inet addr:xxx.xxx.xxx.101  Bcast:xxx.xxx.xxx.255  Mask:255.255.255.0
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:31500 errors:0 dropped:0 overruns:0 frame:0
          TX packets:25697 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:24531867 (24.5 MB)  TX bytes:3058922 (3.0 MB)
          Interrupt:34 Memory:fa000000-fa012700

eth3      Link encap:Ethernet  HWaddr 18:a9:05:68:3c:64
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:33 Memory:f8000000-f8012700

eth4      Link encap:Ethernet  HWaddr 00:1b:21:17:7b:f5
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

eth5      Link encap:Ethernet  HWaddr 00:1b:21:17:7b:f4
          inet addr:xxx.xxx.xxx.102  Bcast:xxx.xxx.xxx.255  Mask:255.255.255.0
          inet6 addr: fe80::21b:21ff:fe17:7bf4/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1123585 errors:0 dropped:0 overruns:0 frame:0
          TX packets:137240 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1343871573 (1.3 GB)  TX bytes:13414623 (13.4 MB)

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:15633 errors:0 dropped:0 overruns:0 frame:0
          TX packets:15633 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:5245636 (5.2 MB)  TX bytes:5245636 (5.2 MB)

root#route -n

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
xxx.xxx.xxx.0    0.0.0.0         255.255.255.0   U     0      0        0 eth5
0.0.0.0         xxx.xxx.xxx.1    0.0.0.0         UG    100    0        0 eth5



root# traceroute xxx.xxx.xxx.2
traceroute to xxx.xxx.xxx.101 (xxx.xxx.xxx.101), 30 hops max, 60 byte packets
 1  node1..unx.xxx.com (xxx.xxx.xxx.101)  0.031 ms  0.009 ms  0.009 ms
    Code:
    root# ifconfig
eth5      Link encap:Ethernet  HWaddr 00:1b:21:17:7b:f4
          inet addr:xxx.xxx.xxx.102  Bcast:xxx.xxx.xxx.255  Mask:255.255.255.0
          inet6 addr: fe80::21b:21ff:fe17:7bf4/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1125794 errors:0 dropped:0 overruns:0 frame:0
          TX packets:137568 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1344106455 (1.3 GB)  TX bytes:13460014 (13.4 MB)

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:15785 errors:0 dropped:0 overruns:0 frame:0
          TX packets:15785 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:5289356 (5.2 MB)  TX bytes:5289356 (5.2 MB)
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  6. 06-12-2010 #6
    Irithori
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    The IP xxx.xxx.xxx.101 is assigned to eth2, but the interface is not connected.

    Judging from the routing table, xxx.xxx.xxx.101 should not be accessible.
    I can only imagine, that the interface was connected at some point in time and some arp redirect is going on.
    ie: the traffic to x.x.x.101 is routed through x.x.x.102

    Anyway, as
    - x.x.x.102 is the IP you want
    - and its interface eth5 is connected
    it should be save to just shut down eth2

    You can use
    Code:
    ifdown eth2
    or
    Code:
    ifconfig eth2 down
    After that,
    - xxx.xxx.xxx.101 should not respond to ping or ssh
    - and ifconfig -a should not show the IP anymore

    This should do as a QuickFix.
    Ops can deal with checking the network-config files on monday
    You must always face the curtain with a bow.
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  7. 06-12-2010 #7
    Triton46
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    I ran ifconfig eth2 down on Friday and ifconfig does not show it. When I run "ifdown eth2" it confirms it is down:

    Code:
    root# ifdown eth2
ifdown: interface eth2 not configured
    Code:
    I'm still able to ssh to it though:
root@node1:~# ssh xxx.xxx.xxx.101
root@node2:~# exit
logout
Connection to xxx.xxx.xxx.101 closed.
root@node1:~# ssh xxx.xxx.xxx.102
root@node2:~# exit
logout
Connection to xxx.xxx.xxx.102 closed.
    Also, /etc/network/interfaces is configured to be static for xxx.xxx.xxx.102.
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  8. 06-12-2010 #8
    Irithori
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    Hmm, maybe x.x.x.102 *is* a different machine after all?

    Let's get that device eth2 out of the equation.
    Please assign a completely non-related IP, like 10.217.4.54.
    Explanation: 10.0.0.0/8 is a private net.
    I picked some random numbers after 10.a.b.c, so it is very unlikey that this IP is used in your network.
    And even if, the device is not connected. So no worries

    Code:
    ifconfig eth2 10.217.4.54
    If you can still ping and ssh into xxx.xxx.xxx.101 after that,
    then it *has* to be a different machine.
    Maybe the hostname is a duplicate then.

    You could check by
    Code:
    uptime
    on both x.x.x.101 and x.x.x.102
    You must always face the curtain with a bow.
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  9. 06-12-2010 #9
    Irithori
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    A more uniq identifier than just uptime on both 101 and 102 would be
    Code:
    ifconfig -a | grep HWaddr
    You must always face the curtain with a bow.
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  10. 06-13-2010 #10
    Triton46
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    It's definitely the same machine, I can leave a file and then ssh to the other IP and find the same file.

    I changed the IP and it seems to work...will test the app and see if that gets me past the problem.
    Code:
    root@node2:~# ssh xxx.xxx.xxx.101
ssh: connect to host xxx.xxx.xxx.101 port 22: No route to host
    Code:
    root@node2:~# uptime
 21:31:34 up 1 day, 11:42,  4 users,  load average: 0.00, 0.00, 0.00
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