Red Hat / CentOS IPv6 Network Configuration

by VIVEK GITE on JANUARY 23, 2009 · 15 COMMENTS

Q. How do I configure static IPv6 networking under RHEL 5.x / Fedora / CentOS Linux?
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A. Red Hat / CentOS / Fedora RHEL support IPv6 out of box. All you have to do is update two files and turn on networking.

You need to update and configure following files for IPv6 configuration:

<!--[if !supportLists]-->1.     <!--[endif]-->/etc/sysconfig/network : Turn on networking in this file.

<!--[if !supportLists]-->2.     <!--[endif]-->/etc/sysconfig/network-scripts/ifcfg-eth0 : Set default IPv6 router IP and server IP address in this file.

Open /etc/sysconfig/network file, enter:
# vi /etc/sysconfig/network
Append following line:

NETWORKING_IPV6=yes

Open /etc/sysconfig/network-scripts/ifcfg-eth0 (1st network config file)
# vi /etc/sysconfig/network-scripts/ifcfg-eth0
Append following config directives for IPv6:

IPV6INIT=yes

IPV6ADDR=<IPv6-IP-Address>

IPV6_DEFAULTGW=<IPv6-IP-Gateway-Address>

Here is my sample file with mix of IPv4 and IPv6 assigned to eth0:

DEVICE=eth0

BOOTPROTO=static

ONBOOT=yes

HWADDR=00:30:48:33:bc:33

IPADDR=202.54.1.5

GATEWAY=202.54.1.3

NETMASK=255.255.255.248

IPV6INIT=yes

IPV6ADDR=2607:f0d0:1002:0011:0000:0000:0000:0002

IPV6_DEFAULTGW=2607:f0d0:1002:0011:0000:0000:0000:0001

Where,

<!--[if !supportLists]-->§  <!--[endif]-->NETWORKING_IPV6=yes|no - Enable or disable global IPv6 initialization.

<!--[if !supportLists]-->§  <!--[endif]-->IPV6INIT=yes - Enable or disable IPv6 configuration for all interfaces.

<!--[if !supportLists]-->§  <!--[endif]-->IPV6ADDR=2607:f0d0:1002:0011:0000:0000:0000:0002 - Specify a primary static IPv6 address here.

<!--[if !supportLists]-->§  <!--[endif]-->IPV6_DEFAULTGW=2607:f0d0:1002:0011:0000:0000:0000:0001 - Add a default route through specified gateway.

Save and close the file. Restart networking:
# service network restart
Verify your configuration by pinging ipv6 enabled site such as ipv6.google.com:
$ ping6 ipv6.google.com
Sample output:

PING ipv6.google.com(2001:4860:b002::68) 56 data bytes

64 bytes from 2001:4860:b002::68: icmp_seq=1 ttl=59 time=93.2 ms

64 bytes from 2001:4860:b002::68: icmp_seq=2 ttl=59 time=95.0 ms

64 bytes from 2001:4860:b002::68: icmp_seq=3 ttl=59 time=94.2 ms

64 bytes from 2001:4860:b002::68: icmp_seq=4 ttl=59 time=95.2 ms

64 bytes from 2001:4860:b002::68: icmp_seq=5 ttl=59 time=94.8 ms

64 bytes from 2001:4860:b002::68: icmp_seq=6 ttl=59 time=95.1 ms

64 bytes from 2001:4860:b002::68: icmp_seq=7 ttl=59 time=93.3 ms

64 bytes from 2001:4860:b002::68: icmp_seq=8 ttl=59 time=93.8 ms

--- ipv6.google.com ping statistics ---

8 packets transmitted, 8 received, 0% packet loss, time 7010ms

rtt min/avg/max/mdev = 93.268/94.376/95.268/0.799 ms

Traces path to a network host, enter:
$ traceroute6 ipv6.google.com
Print default IPv6 routing table, enter:
$ route -n -A inet6
Sample output:

Kernel IPv6 routing table

Destination                                 Next Hop                                Flags Metric Ref    Use Iface

::1/128                                     ::                                      U     0      42531       1 lo

::62.41.14.144/128                          ::                                      U     0      0        1 lo

::127.0.0.1/128                             ::                                      U     0      0        1 lo

::/96                                       ::                                      U     256    0        0 sit0

2001:470:1f04:55a::2/128                    ::                                      U     0      15201       1 lo

2001:470:1f04:55a::/64                      ::                                      U     256    0        0 sit1

fe80::4833:22f4/128                         ::                                      U     0      0        1 lo

fe80::212:3fff:fe75:fa0d/128                ::                                      U     0      0        1 lo

fe80::/64                                   ::                                      U     256    0        0 eth0

fe80::/64                                   ::                                      U     256    0        0 sit1

ff00::/8                                    ::                                      U     256    0        0 eth0

ff00::/8                                    ::                                      U     256    0        0 sit1

::/0                                        ::                                      U     1      0        0 sit1

Once IPv6 configured properly, you need to setup IPv6 firewall using ip6tables command under Linux.

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{ 15 comments… read them below or add one }

1Sean June 15, 2010

you have no ipv6 mask :(

REPLY

2Beau July 13, 2010

Thanks so much for this article. It is exactly what I have been looking for. I will recommend this article. Keep up the good work.

REPLY

3Pete July 15, 2010

Nice reminders, but I’d like to make two suggestions:

1. Since the gateways are not specific to an interface, I keep the default gateway stuff (v4 and v6) in /etc/sysconfig/network.

2. I also don’t like the v6 autoconf for servers, so I turn it off in /etc/sysconfig/network: IPV6_AUTOCONF=no

Thanks for the quick tips.

Pete

REPLY

4Steve September 27, 2010

So how would one find out there IPV6 address to use as a static one and what the default gw IPV6 address us to use?

I know the IPV4 addresses > how do i find its IPV6?

Thanks in advance

REPLY

5SH October 7, 2010

I try to add another interface (ifcfg-eth0:1) with the same IPv6 lines as in ifcfg-eth0, but the IPv6 does not appear when I use ifconfig. How can I assign an IPv6 to another network interface?

REPLY

6Pete October 7, 2010

Use IPV6ADDR_SECONDARIES in ifcfg-eth0. Generally, v6 devices expect to have multiple addresses. If you do an ifconfig on eth0, you’ll probably see at least two v6 addresses already (one a link-local scope and one a global scope).

IPV6ADDR_SECONDARIES=”[/] …” (optional)
A list of secondary IPv6 addresses (e.g. useful for virtual hosting)
Example:
IPV6ADDR_SECONDARIES=”3ffe:ffff:0:1::10 3ffe:ffff:0:2::11/128″

REPLY

7S!FE October 20, 2010

Is there any directive to make network service start at boot time.

REPLY

8Vivek Gite October 20, 2010

Try

 chkconfig network on

REPLY

9S!FE October 20, 2010

I think that works for me, thanks Mr Vivek.

REPLY

10tomas November 16, 2010

Just a question. How can I calculate usable hosts address? I have assigned IPv6 /48 network and need single adress for each server, for example
3x IPv6 address for server-1
2x IPv6 address for server-2
etc …

REPLY

11Joel Snyder February 27, 2011

ipv6.google.com doesn’t resolve today, so it’s a bad example. Try http://www.v6.facebook.com.

REPLY

12Monster June 10, 2011

any idea how to configure IPv6 in bridge for RH based OS?

REPLY

13Iain Kay July 22, 2011

I have a question. If one has setup a CentOS server, and it is now in production sitting online in use 24/7 with IPv4, is it possible to add IPv6 to it without having to restart the network service?

What I have tried:
$ modprobe ipv6
$ ifconfig eth0 && ifconfig xenbr0

By this point there are no ipv6 addresses shown in ifconfig

$ ip addr add 2001:xx:xx:xx:1::2/64 dev xenbr0

By this point I still have no ipv6 addresses in ifconfig, all I get is:
RTNETLINK answers: Operation not supported

If I absolutely have to reboot the server then I will find a good point to do so and do it but if it’s even remotely possible to do without then that would be ideal. The server hosts Xen virtual machines using bridged networking configuration and somehow I doubt that restarting the network service would play nice with them and come back automatically at Virtual Machine level.

REPLY

14George October 17, 2011

Hi I dont find /etc/sysconfig/network-scripts/ifcfg-eth0, I only have /etc/sysconfig/network-scripts/ifcfg-lo…….what can I do ? Help me please

REPLY

15Calum November 2, 2011

George – how about cp /etc/sysconfig/network-scripts/ifcfg-lo /etc/sysconfig/network-scripts/ifcfg-eth0