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7 Replies Latest reply: Feb 6, 2013 9:08 PM by 140295 RSS

Change Default gateway

140295 Newbie
Currently Being Moderated
Hi..I have to change default gateway in my linux machine. Its OS is RHEL6.
I followed following steps.
1.run command ip route to check current default gateway
2.delete that gateway with command
route del default gw x.x.x.x eth2
3.Add new gatewy with command below
route add default gateway x.x.x.x eth0
4.Also ensure /etc/sysconfig/network has new gateway entry with eth name in it.
NETWORKING=yes
HOSTNAME=N1
GATEWAY=x.x.x.x
GATEWAYDEV=eth0

But when we restart network service it moves back to old gateway.

Kindly let me know how to make it permanent.

Thanks !!
  • 1. Re: Change Default gateway
    Paul M. Oracle ACE
    Currently Being Moderated
    Did you try using system-config-network command ?
  • 2. Re: Change Default gateway
    140295 Newbie
    Currently Being Moderated
    Hi..i tried running this from command prompt but it shows command not found.
  • 3. Re: Change Default gateway
    bigdelboy Pro
    Currently Being Moderated
    iam_dushyant wrote:
    Hi..I have to change default gateway in my linux machine. Its OS is RHEL6.
    I followed following steps.
    1.run command ip route to check current default gateway
    2.delete that gateway with command
    route del default gw x.x.x.x eth2
    3.Add new gatewy with command below
    route add default gateway x.x.x.x eth0
    4.Also ensure /etc/sysconfig/network has new gateway entry with eth name in it.
    NETWORKING=yes
    HOSTNAME=N1
    GATEWAY=x.x.x.x
    GATEWAYDEV=eth0

    But when we restart network service it moves back to old gateway.

    Kindly let me know how to make it permanent.

    Thanks !!
    My thoughts are, and having a quick look at an OL 6.3 system here ... is that:

    GATEWAY=x.x.x.x
    DEFROUTE=yes

    is in the ifcfg-ethX file.

    And that:

    GATEWAY=x.x.x.x
    GATEWAYDEV=eth0

    are no longer in the /etc/sysconfig/network file.

    ...

    Also keep out a lookout at any /etc/default-routes files ( possibly consider renaming it should it exist).

    ...

    Looking at your latest post you may need to install system-config-network to get that utility ...
  • 4. Re: Change Default gateway
    Dude! Guru
    Currently Being Moderated
    As far as I know, entries in /etc/sysconfig/network, e.g. GATEWAY= are only used only if there there is no corresponding entry in the ifcfg-ethX interface specific config file, which takes precedence.
  • 5. Re: Change Default gateway
    140295 Newbie
    Currently Being Moderated
    Hi..my data center is in location x and person accessing it on Y over wan.Server has linux RHEL 6.2 OS and has 4 nic card with their different ip(Ip1,Ip2,Ip3 & Ip4),netmask and gateway (gw1 to gw4). Person from Y is able to ping gateway gw1 to gw4. When he tried to ping ip , he is able to ping Ip1.

    Do i need to define default gateway for all ip? How shall i configure default gateway for rest of IP's?


    INTERFACE     IP     Gateway     Subnet     Remarks
    ce0     192.12.80.1     192.12.80.254     255.255.255.0     
    ce0:1     192.12.80.2     192.12.80.254     255.255.255.0     It is virtual IP
    ce1     192.12.81.5     192.12.80.126     255.255.255.128     
    ce2     192.12.83.4     192.12.80.254     255..255.255.192     
    ce3     192.168.176.1     192.168.176.254     255.255.255.0     

    Pls find below details as required.


    [root@nth1 ~]# ifconfig -a
    eth0 Link encap:Ethernet HWaddr 00:1A:64:D3:FD:54
    inet addr:192.12.80.1 Bcast:10.2.180.255 Mask:255.255.255.0
    inet6 addr: fe80::21a:64ff:fed3:fd54/64 Scope:Link
    UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
    RX packets:10955 errors:0 dropped:0 overruns:0 frame:0
    TX packets:4868 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:1000
    RX bytes:3273759 (3.1 MiB) TX bytes:1554244 (1.4 MiB)
    Interrupt:16 Memory:ce000000-ce012800

    eth1 Link encap:Ethernet HWaddr 00:1A:64:D3:FD:56
    inet addr:192.12.81.5 Bcast:10.2.181.127 Mask:255.255.255.128
    inet6 addr: fe80::21a:64ff:fed3:fd56/64 Scope:Link
    UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
    RX packets:6760 errors:0 dropped:0 overruns:0 frame:0
    TX packets:5464 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:1000
    RX bytes:7758932 (7.3 MiB) TX bytes:522470 (510.2 KiB)
    Interrupt:17 Memory:ca000000-ca012800

    eth2 Link encap:Ethernet HWaddr 00:15:17:78:5F:9E
    inet addr:192.12.83.4 Bcast:10.2.181.191 Mask:255.255.255.192
    inet6 addr: fe80::215:17ff:fe78:5f9e/64 Scope:Link
    UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
    RX packets:4458 errors:0 dropped:0 overruns:0 frame:0
    TX packets:3930 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:1000
    RX bytes:4428694 (4.2 MiB) TX bytes:365910 (357.3 KiB)
    Interrupt:16 Memory:c7ee0000-c7f00000

    eth3 Link encap:Ethernet HWaddr 00:15:17:78:5F:9F
    inet addr:192.168.176.1 Bcast:192.168.176.255 Mask:255.255.255.0
    inet6 addr: fe80::215:17ff:fe78:5f9f/64 Scope:Link
    UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
    RX packets:3634 errors:0 dropped:0 overruns:0 frame:0
    TX packets:3558 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:1000
    RX bytes:896806 (875.7 KiB) TX bytes:896716 (875.6 KiB)
    Interrupt:17 Memory:c7ea0000-c7ec0000

    eth4 Link encap:Ethernet HWaddr 00:15:17:78:61:94
    UP 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:17 Memory:c5fe0000-c6000000

    eth5 Link encap:Ethernet HWaddr 00:15:17:78:61:95
    UP 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:18 Memory:c5fa0000-c5fc0000

    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:3755 errors:0 dropped:0 overruns:0 frame:0
    TX packets:3755 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:0
    RX bytes:1096013 (1.0 MiB) TX bytes:1096013 (1.0 MiB)

    [root@nth1 ~]# route -n
    Kernel IP routing table
    Destination Gateway Genmask Flags Metric Ref Use Iface
    10.2.181.128 0.0.0.0 255.255.255.192 U 0 0 0 eth2
    10.2.181.0 0.0.0.0 255.255.255.128 U 0 0 0 eth1
    192.168.176.0 0.0.0.0 255.255.255.0 U 0 0 0 eth3
    10.2.180.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
    169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 eth0
    169.254.0.0 0.0.0.0 255.255.0.0 U 1003 0 0 eth1
    169.254.0.0 0.0.0.0 255.255.0.0 U 1004 0 0 eth2
    169.254.0.0 0.0.0.0 255.255.0.0 U 1005 0 0 eth3
    0.0.0.0 192.12.80.254 0.0.0.0 UG 0 0 0 eth0
    [root@nth1 ~]#
    [root@nth1 ~]# netstat -nr
    Kernel IP routing table
    Destination Gateway Genmask Flags MSS Window irtt Iface
    10.2.181.128 0.0.0.0 255.255.255.192 U 0 0 0 eth2
    10.2.181.0 0.0.0.0 255.255.255.128 U 0 0 0 eth1
    192.168.176.0 0.0.0.0 255.255.255.0 U 0 0 0 eth3
    10.2.180.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
    169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
    169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1
    169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth2
    169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth3
    0.0.0.0 192.12.80.254 0.0.0.0 UG 0 0 0 eth0

    Thanks !!

    Edited by: iam_dushyant on Feb 6, 2013 3:21 AM
  • 6. Re: Change Default gateway
    bigdelboy Pro
    Currently Being Moderated
    Not my best area, but as far as I know in static routing you may have one default gateway that is used for a all address not on a local subnet for which a specific static route is not available.

    If I am not mistaken looking at:
    INTERFACE IP Gateway Subnet Remarks
    ce0 192.12.80.1 192.12.80.254 255.255.255.0
    ce0:1 192.12.80.2 192.12.80.254 255.255.255.0 It is virtual IP
    ce1 192.12.81.5 192.12.80.126 255.255.255.128
    ce2 192.12.83.4 192.12.80.254 255..255.255.192
    ce3 192.168.176.1 192.168.176.254 255.255.255.0 
    Taking interface ce1 the gateway (192.12.80.126) does not appear to be on the subnet of the IP {192.12.81.5 netmask 255.255.255.128}

    Should the gateway be 192.12.81.126 this would make more sense. My guess would be GATEWAY=192.12.80.126 with DEFROUTE=no in the ifcfg-eth1 file would achieve this.

    ....

    I also note the line "inet addr:192.12.81.5 Bcast:10.2.181.127 Mask:255.255.255.128" and again the broadcast address does not look right for the subnet. I suggest checking the configuration carefully.
  • 7. Re: Change Default gateway
    140295 Newbie
    Currently Being Moderated
    Thanks ..its type error..My apology.

    INTERFACE IP Gateway Subnet Remarks
    ce0 192.12.80.1 192.12.80.254 255.255.255.0
    ce0:1 192.12.80.2 192.12.80.254 255.255.255.0 It is virtual IP
    ce1 192.12.81.5 192.12.81.126 255.255.255.128
    ce2 192.12.83.4 192.12.83.254 255..255.255.192
    ce3 192.168.176.1 192.168.176.254 255.255.255.0

    In eth1,defroute is no.

    Thanks

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