$ sudo ip netns exec router sysctl net.ipv4.ip_forward=1
net.ipv4.ip_forward = 1
</pre>
*ルーターを介した接続成功
<pre>
$ sudo ip netns exec ns1 ping -c 3 198.51.100.1
PING 198.51.100.1 (198.51.100.1) 56(84) bytes of data.
64 bytes from 198.51.100.1: icmp_seq=1 ttl=63 time=0.208 ms
64 bytes from 198.51.100.1: icmp_seq=2 ttl=63 time=0.114 ms
64 bytes from 198.51.100.1: icmp_seq=3 ttl=63 time=0.134 ms
--- 198.51.100.1 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2032ms
rtt min/avg/max/mdev = 0.114/0.152/0.208/0.040 ms
</pre>