On Wed, December 23, 2015 8:06 am, Meikel wrote: > Hi folks, > > I have a server at Soyoustart.com (which is a brand of OVH). I run > CentOS 6.7 and have problems with network configuration. > > I want to add a second public ip (failover ip) to the server and did > follow the instructions in the CentOS-section of > http://hilfe.ovh.de/AdministrationIpAliasHinzufuegen > > After executing the required steps I'm not able to reach the host via > the second ip from an external host. I tried it with ping and with ssh > commands. > > Here the content of the config files (I anonymized the server ip with > xx.xx.xx.xx and the failover ip with yy.yy.yy.yy): > > $ cat /etc/sysconfig/network > NETWORKING=yes > HOSTNAME=<name-of-my-host> > NOZEROCONF=true > GATEWAY=xx.xx.xx.254 > > $ cat /etc/sysconfig/network-scripts/ifcfg-eth0 > DEVICE=eth0 > BOOTPROTO=static > IPADDR=xx.xx.xx.xx > NETMASK=255.255.255.0 > ONBOOT=yes > GATEWAY=xx.xx.xx.254 > > $ cat /etc/sysconfig/network-scripts/ifcfg-eth0:0 > DEVICE=eth0:0 > BOOTPROTO=static > IPADDR=yy.yy.yy.yy > NETMASK=255.255.255.255 > ONBOOT=yes If I understand IP networking correctly, you only can have "aliases" of the interface appear on the _same_ network segment (I'm tempted to say same class C network) as the main IP of interface, say you have: DEVICE=eth0 IPADDR=x.y.z.w NETMASK=255.255.255.0 GATEWAY=x.y.z.254 Then with the restriction I mentioned you can have alias: DEVICE=eth0:0 IPADDR=x.y.z.a NETMASK=255.255.255.255 Note that "x.y.z." part is the same in both IPs. Somebody may correct me if I'm wrong. Valeri > > When I restart the network I get a message (two times) saying "RTNETLINK > answers: Operation not supported". > > $ service network restart > Schnittstelle eth0 beenden: [ OK ] > Loopback-Schnittstelle beenden: [ OK ] > Loopback-Schnittstelle hochfahren: [ OK ] > Schnittstelle eth0 hochfahren: Determining if ip address xx.xx.xx.xx is > already in use for device eth0... > RTNETLINK answers: Operation not supported > RTNETLINK answers: Operation not supported > [ OK ] > > I can see two interfaces eth0 and eth0:0 > > $ LANG="" ifconfig > eth0 Link encap:Ethernet HWaddr ..:..:..:..:..:.. > inet addr:xx.xx.xx.xx Bcast:xx.xx.xx.255 Mask:255.255.255.0 > UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 > RX packets:11122 errors:0 dropped:0 overruns:0 frame:0 > TX packets:14371 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 txqueuelen:1000 > RX bytes:1362900 (1.2 MiB) TX bytes:3462327 (3.3 MiB) > Interrupt:20 Memory:fe500000-fe520000 > > eth0:0 Link encap:Ethernet HWaddr ..:..:..:..:..:.. > inet addr:yy.yy.yy.yy Bcast:yy.yy.yy.yy Mask:255.255.255.255 > UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 > Interrupt:20 Memory:fe500000-fe520000 > > lo Link encap:Local Loopback > inet addr:127.0.0.1 Mask:255.0.0.0 > UP LOOPBACK RUNNING MTU:65536 Metric:1 > RX packets:3096 errors:0 dropped:0 overruns:0 frame:0 > TX packets:3096 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 txqueuelen:0 > RX bytes:274948 (268.5 KiB) TX bytes:274948 (268.5 KiB) > > > I'm able to reach the host from another host (outside OVH network) via > xx.xx.xx.xx (I use ping and ssh), but not via yy.yy.yy.yy. > > Just to be sure that there isn't an issue with the firewall I did > "service iptables stop" and ran the "ping" and "ssh" commands again with > the same result. For ip xx.xx.xx.xx it works, but not for yy.yy.yy.yy. > > Not sure if this is important, just in case it matters, some additional > information: > > IPv6 is disabled by kernel parameter "ipv6.disable=1" in /etc/grub.conf > > The two mac addresses I see for eth0 and eth0:0 with the "ifconfig" > command are the same. In the OVH/Soyoustart.com GUI I created a virtual > mac for the failover ip, I'm not sure if that virtual mac should come > into play somewhere? > > $ uname -a > Linux <name-of-my-host> 2.6.32-573.12.1.el6.x86_64 #1 SMP Tue Dec 15 > 21:19:08 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux > > $ LANG="" route > Kernel IP routing table > Destination Gateway Genmask Flags Metric Ref Use Iface > xx.xx.xx.0 * 255.255.255.0 U 0 0 0 eth0 > default vss-gw-6k.fr.eu 0.0.0.0 UG 0 0 0 eth0 > > Why is yy.yy.yy.yy not reachable from outside? What am I doing wrong or > what can I do to narrow down the problem? > > Regards, > > Meikel > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos > ++++++++++++++++++++++++++++++++++++++++ Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ++++++++++++++++++++++++++++++++++++++++