I try to configure static IPv4 & IPv6 configuration on CentOS 6.2.The configuration below works perfectly :# ifconfig eth0 x.x.x.x/29# route add defalt gw x.x.x.y# ip addr add dev eth0 XXXX:C810:3001:D00::3/56# ip -6 route add default XXXX:C810:3001:D00::1However, I want to keep this configuration after a reboot.So I made the following configuration:Enabling IPv6[root@test network-scripts]# cat /etc/sysconfig/networkNETWORKING=yesHOSTNAME=test.netNETWORKING_IPV6=yesInterface Configuration[root@test network-scripts]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE=eth0BOOTPROTO=staticONBOOT=yesHWADDR=2C:C3:AC:A8:C3:3EIPADDR=x.x.x.xGATEWAY=x.x.x.xNETMASK=255.255.255.248TYPE=EthernetIPV6INIT=yesIPV6ADDR=XXXX:C810:3001:D00::3/56IPV6_DEFAULTGW=XXXX:C810:3001:D00::1DNS1=208.67.222.222DNS2=208.67.220.220# Only DNS{1,2} according to /usr/share/doc/initscripts-9.03.27/sysconfig.txt# DNS3=2620:0:ccc::2# DNS4=2620:0:ccD::2Restarting the Network[root@test network-scripts]# service network restartArrt de l'interface eth0 :  tat du priphrique&nbsp;: 3 (dconnect)                                                           [  OK  ]Arrt de l'interface loopback :                            [  OK  ]Activation de l'interface loopback :                       [  OK  ]Activation de l'interface eth0 :  tat de connexion active&nbsp;: activationtat de chemin actif&nbsp;: /org/freedesktop/NetworkManager/ActiveConnection/3tat&nbsp;: activConnexion active                                                           [  OK  ][root@test network-scripts]# cat /var/log/messageMar 13 14:32:13 test NetworkManager[8299]: <info> (eth0): device state change: 8 -> 3 (reason 39)Mar 13 14:32:13 test NetworkManager[8299]: <info> (eth0): deactivating device (reason: 39).Mar 13 14:32:13 test avahi-daemon[8311]: Withdrawing address record for x.x.x.x on eth0.Mar 13 14:32:13 test avahi-daemon[8311]: Leaving mDNS multicast group on interface eth0.IPv4 with address x.x.x.x.Mar 13 14:32:13 test avahi-daemon[8311]: Interface eth0.IPv4 no longer relevant for mDNS.Mar 13 14:32:14 test kernel: lo: Disabled Privacy ExtensionsMar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) starting connection 'System eth0'Mar 13 14:32:14 test NetworkManager[8299]: <info> (eth0): device state change: 3 -> 4 (reason 0)Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) scheduled...Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) started...Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) scheduled...Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) complete.Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) starting...Mar 13 14:32:14 test NetworkManager[8299]: <info> (eth0): device state change: 4 -> 5 (reason 0)Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) successful.Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) scheduled.Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) complete.Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) started...Mar 13 14:32:14 test NetworkManager[8299]: <info> (eth0): device state change: 5 -> 7 (reason 0)Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 4 of 5 (IP4 Configure Get) scheduled...Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Beginning IP6 addrconf.Mar 13 14:32:14 test avahi-daemon[8311]: Withdrawing address record for fe80::1ec1:deff:feb8:a2fd on eth0.Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) complete.Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 4 of 5 (IP4 Configure Get) started...Mar 13 14:32:14 test NetworkManager[8299]: <info> Activation (eth0) Stage 4 of 5 (IP4 Configure Get) complete.Mar 13 14:32:15 test avahi-daemon[8311]: Registering new address record for fe80::1ec1:deff:feb8:a2fd on eth0.*.Mar 13 14:32:35 test NetworkManager[8299]: <info> (eth0): IP6 addrconf timed out or failed.Mar 13 14:32:35 test NetworkManager[8299]: <info> Activation (eth0) Stage 4 of 5 (IP6 Configure Timeout) scheduled...Mar 13 14:32:35 test NetworkManager[8299]: <info> Activation (eth0) Stage 4 of 5 (IP6 Configure Timeout) started...Mar 13 14:32:35 test NetworkManager[8299]: <info> Activation (eth0) Stage 5 of 5 (IP Configure Commit) scheduled...Mar 13 14:32:35 test NetworkManager[8299]: <info> Activation (eth0) Stage 4 of 5 (IP6 Configure Timeout) complete.Mar 13 14:32:35 test NetworkManager[8299]: <info> Activation (eth0) Stage 5 of 5 (IP Configure Commit) started...Mar 13 14:32:35 test avahi-daemon[8311]: Joining mDNS multicast group on interface eth0.IPv4 with address x.x.x.x.Mar 13 14:32:35 test avahi-daemon[8311]: New relevant interface eth0.IPv4 for mDNS.Mar 13 14:32:35 test avahi-daemon[8311]: Registering new address record for x.x.x.x on eth0.IPv4.Mar 13 14:32:36 test NetworkManager[8299]: <info> (eth0): device state change: 7 -> 8 (reason 0)Mar 13 14:32:36 test NetworkManager[8299]: <info> Policy set 'System eth0' (eth0) as default for IPv4 routing and DNS.Mar 13 14:32:36 test NetworkManager[8299]: <info> Activation (eth0) successful, device activated.Mar 13 14:32:36 test NetworkManager[8299]: <info> Activation (eth0) Stage 5 of 5 (IP Configure Commit) complete.IPv6 configuration is not working ...[root@test network-scripts]# ip addr show1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00    inet 127.0.0.1/8 scope host lo    inet6 ::1/128 scope host        valid_lft forever preferred_lft forever2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000    link/ether 1c:c1:de:b8:a3:fd brd ff:ff:ff:ff:ff:ff    inet x.x.x.x/29 brd x.x.x.x scope global eth0    inet6 fe80::1ec1:deff:feb8:a3fd/64 scope link        valid_lft forever preferred_lft foreverIPv6 addresses of the resolvers are not even in the resolv.conf !Did I miss a configuration step ? I thought that the IPv6 configuration would be a formality ..[root@test network-scripts]# lsb_release -aLSB Version:    :core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarchDistributor ID:    CentOSDescription:    CentOS release 6.2 (Final)Release:    6.2Codename:    Final
Static IPv4 & IPv6 configuration on CentOS 6.2
centos;networking;ipv6;ipv4
Network Manager is trying to override your static configuration settings. As root or sudo user, run:service NetworkManager stopIf you don't have service, try:/etc/init.d/NetworkManager stopAlso, you can set the static interfaces to not be managed by the NetworkManager, which is what I did in my CentOS configs merely by adding the lineNM_CONTROLLED=noto your static config files. Your static configuration files don't have that line, meaning the NetworkManager will try to control those interfaces instead of ignoring them. See here for reference on disabling and/or uninstalling NM. 