Setting up bridged LXC containers with static IPs

EthernetCable asked:

I’m trying to setup multiple LXC containers on a host, each with public static IPs of their own.

My host is running the latest Ubuntu. It has a single network interface named eth0. The static IPs are pingable from the internet and are named eth0:210, eth0:211… The numbers after the colon are the least significant byte of the addresses. In addition to these interfaces I have br0 setup on the host’s public IP. There are also the lo, veth2LPP9A, and lxcbr0 interfaces. The lxcbr0 has the address of a private IP.

The host /etc/network/interfaces looks like:

auto br0
iface br0 inet static
        bridge_ports eth0
        bridge_fd 0

So far I’ve used various online sources, including Bridging LXC containers to host eth0 so they can have a public IP to help me set this up.

The container’s config file has: = veth = br0

I’ve removed the static configuration from this file since it caused problems. When I ran lxc-ls –fancy with this configuration, I’d see the same public IP twice in the output. Additionally, it would mess with the subnet configuration of the container’s /etc/network/interfaces.

Speaking of the container’s interfaces file, it looks a bit like:

auto eth0
iface eth0 inet static
        address [...]
        #gateway [...]

        post-up route add [...] dev eth0
        post-up route add default gw [...]
        post-down route del [...] dev eth0
        post-down route del default gw [...]

I had to comment out the gateway and add the route add commands to this file. Otherwise, the container would take minutes to boot.

The /proc/sys/net/bridge/bridge-nf-* files on the host are all set to 0. The /proc/sys/net/ipv4/ip_forward value is 1.

The problem is, even though the container’s “route -n” looks like it should, I can’t ping out of the container. SSHing to what should be the container’s IP, connects me to the host.

EDIT: Removing the container’s static IP from the host did help, but now I’m getting a new error. Trying to ping the container from the host results in Redirect HostFrom , New nexthop. The packets are just going from the gateway to the host, repeatedly. Running a traceroute from the host shows that the first stop is at the gateway. Then all of the other routes are * * *. I get the same problem regardless if the container is online or not.

My answer:

Since you are bridging, you need to set the IP addresses in the container only, and not on the host. The host should only have its own IP address(es).

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