https://blogs.igalia.com/dpino/2016/04/10/network-namespaces/
CSDN上NameSpace好多文章都是翻译的这个
在后面还提供了一个非常骚气的操作：
$ ip netns exec ns1 /bin/bash --rcfile <(echo "PS1=\"namespace ns1> \"")
另外还介绍了Linux怎么配置转发，但是太长了呀，记不住，而且要NAT...
# Share internet access between host and NS.
# Enable IP-forwarding.
echo 1 > /proc/sys/net/ipv4/ip_forward
# Flush forward rules, policy DROP by default.
iptables -P FORWARD DROP
iptables -F FORWARD
# Flush nat rules.
iptables -t nat -F
# Enable masquerading of 10.200.1.0.
iptables -t nat -A POSTROUTING -s 10.200.1.0/255.255.255.0 -o eth0 -j MASQUERADE
# Allow forwarding between eth0 and v-eth1.
iptables -A FORWARD -i eth0 -o v-eth1 -j ACCEPT
iptables -A FORWARD -o eth0 -i v-eth1 -j ACCEPT
