Configuring IPv6 on Linux CentOS

Linux logoConfiguring IPv6 on your linux server is this easy if your ISP is IPv6-ready (if not, see Tunnelbroker links below) on CentOS 5 and 7:

vi /etc/sysconfig/network-scripts/ifcfg-my_interface file, note the settings that start with “IPV6” and update them:

  1. DNS2=2001:4860:4860::8888 – Google Public IPv6 nameserver
  2. IPV6INIT=yes – This is needed when configuring IPv6 on the interface
  3. IPV6ADDR=my_ipv6-address – Specifies a primary static IPv6 address
  4. IPV6_DEFAULTGW=my_ipv6-address – Adds a default route through the interface specified

You don’t need new IPv6 switches, since switching is done at Layer 2. I’m using the old bargain web-managed HP Procurve J9028A. 🙂

(When people say IPv6-capable, that means the management features can be assigned IPv6 addresses, or that it can do Layer 3 routing functions with IPv6 addresses.)

To test:

  1. ping6 ipv6.google.com
    # ping6 ipv6.google.com
    PING ipv6.google.com(sfo07s17-in-x0e.1e100.net (2607:f8b0:4005:80a::200e)) 56 data bytes
    64 bytes from sfo07s17-in-x0e.1e100.net (2607:f8b0:4005:80a::200e): icmp_seq=1 ttl=56 time=1.39 ms
    
  2. traceroute -6 ipv6.google.com
    # traceroute -6 ipv6.google.com 
    traceroute to ipv6.google.com (2607:f8b0:4005:80a::200e), 30 hops max, 80 byte packets
     1  gateway (xxx:xx:x:xxx::1)  3.959 ms  3.978 ms  4.005 ms
     2  10ge7-3.core3.fmt2.he.net (2001:470:0:274::1)  7.859 ms  7.933 ms  11.998 ms
     3  10ge10-5.core1.pao1.he.net (2001:470:0:263::2)  11.296 ms  0.785 ms  11.311 ms
     4  google-as15169.10gigabitethernet8-2.core1.pao1.he.net (2001:470:0:244::2)  0.944 ms  0.946 ms  0.980 ms
     5  2001:4860:0:1004::1 (2001:4860:0:1004::1)  1.471 ms 2001:4860:0:1006::1 (2001:4860:0:1006::1)  1.478 ms 2001:4860:0:1004::1 (2001:4860:0:1004::1)  1.577 ms
     6  2001:4860:0:1::1f71 (2001:4860:0:1::1f71)  1.328 ms  1.266 ms  1.221 ms
     7  sfo07s17-in-x0e.1e100.net (2607:f8b0:4005:80a::200e)  1.150 ms  1.197 ms  1.210 ms
    

Tips:

  1. on CentOS 7, leaving network manager enabled was more successful than attempting to disable it
  2. the files in network-scripts/ are space-sensitive, so don’t use spaces or you will get weird parsing errors
  3. if you’re a Perl programmer, for best results use perl 5.14 or newer and IO::Socket::IP instead of IO::Socket::INET. (Perl 5.10 can work if you upgrade IO::Socket and LWP modules.)
  4. “Check sysctl -a | grep disable_ipv6 output. And if it’s =1, set it to 0.”
  5. “When NetworkManager is running, it may disable ipv6 on the interface if it’s not configured via NM.”

rootusers.com: Configure IPv6 Addresses And Basic Troubleshooting In Linux
google.com: Google Public DNS IP addresses
centos.org: Are you using Network-Manager in no-GUI CentOS 7 Server?

HE Tunnelbroker Links

If your ISP does not support IPv6 yet, you can tunnel traffic in and out of your machine using the HE Tunnelbroker. This is also simple to setup, taking about 5 minutes if your server has IPv6 enabled. (Note that IRC and email traffic to port 25 are filtered to reduce abuse.)

Create Hurricane Tunnel Broker on Raspberry Pi
Hurricane Electric Free IPv6 Tunnel Broker
AWS IPv6 Update – Global Support Spanning 15 Regions & Multiple AWS Services

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