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Setting a Default Gateway in RHEL6

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This can be tricky business. Haste make waist and here is very true: if you mess with specifying parameters in RHEL config file you can end with the situation troubleshooting of which can last several hours.

Some errors like specifying network that does not contain the default router can result in strange and difficult to troubleshoot behavior: If you restart networking (for example using the command service network restart) or reboot the box you lose your default router. At the same time the command

route add default gw 

will work OK.

Default gate way can be specified per interface or like global setting

Global setting specification should be put into /etc/sysconfig/network file


After change you need to restart networking service :

/etc/init.d/networking restart
Interface  eth0 file /etc/sysconfig/network-scripts/ifcfg-eth0 in RHEL 5.8 looks like
# Broadcom Corporation NetXtreme II BCM5709 Gigabit Ethernet

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Old News ;-)

Lost default Gateways after reboot


Lost default Gateways after reboot
I have two clustered ftp servers running RH Enterprise but have an odd problem, after rebooting there are no default gateways when I run ip route.
Both servers have two interface cards on two separate LANs so I have to manually add the default gw's before I can access them from another site.

Does anyone have any idea what is causing this?

Many thanks


Have you got any files in the /etc/sysconfig/network-scripts directory which are similar to this: ifcfg-ethx where x is the ethernet prot number?

This is an extract from one of our files:

HWADDR=xx: xx: xx: xx: xx

This gateway is hard coded into the configuration file for eth1 (I know it can get overwritten, but having a copy handy may help)

That's all I can think of for the moment. If I come up with anything else, I'll let you know.

Oh, are you running with static of dynamic IPs? Is DHCP running and trying to get the network info from a DHCP server on the network?


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Last modified: July 28, 2019