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route command

Linux IPv6 Default Route Not Working

CentOS / Fedora / Red Hat Enterprise / Other Linux distro has weird bug in kernel itself.

I've tested this on Linux 2.6.18-92.1.1.el5 x86_64. The default IPv6 route, as configured in /etc file does not work. You need to add it manually using route command.

# ip route add {IPv-6-IP} dev {device}
# ip route add 2000::/3 dev eth2
Now, you can ping to IPv6 site, enter:
# ping6 ipv6.google.com
Sample output:

PING ipv6.google.com(2001:4860:0:2001::68) 56 data bytes
64 bytes from 2001:4860:0:2001::68: icmp_seq=0 ttl=59 time=37.3 ms
64 bytes from 2001:4860:0:2001::68: icmp_seq=1 ttl=59 time=36.7 ms
64 bytes from 2001:4860:0:2001::68: icmp_seq=2 ttl=59 time=36.9 ms
64 bytes from 2001:4860:0:2001::68: icmp_seq=3 ttl=59 time=36.9 ms

Configure Static Routes In Debian or Red Hat Enterprise Linux

Static routes improves overall performance of your network (especially bandwidth saving). They are also useful in stub networks (i.e. there is only one link to the network). For example, each LAN (located at different offices) is connected to HQ IDC (Internet data center) using single T1/LL/Wan links.

For example under Red Hat/Fedora Linux you can add static router for eth0 network interface by editing /etc/sysconfig/network-scripts/route-eth0 file. Under Debian Linux add static route by editing /etc/network/interface file.

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HP-UX: How Do I configure routing or add route?

You can use route command to configure routing. Syntax is as follows:
route add net {network-address} netmask {subnet} {router-address}

Let us assume your router address is and network ID is, then you can type route command as follows:
# route add net netmask


To add a default route:
# route add default

Verify that (display) routing table is updated (display routing table):
# netstat -nr

Test it i.e. try to ping or send nslookup request:
# ping mycorp.com

To flush all routing entries use command [quite handy to clean your gordian knot ;)] :
# route -f

However if I reboot HPUX box then above routing entries gets removed. To pick up your setting upon each reboot your need to configure Routes in HPUX networking configuration file - /etc/rc.config.d/netconf. To add default router/gateway
# vi /etc/rc.config.d/netconf

Add or modify following entries


Reboot HP-UX system/server to take effect
# shutdown -ry 0