cat /proc/config.gz | gunzip - | grep CONFIG_NET_NS

$ readlink /proc/$$/ns/net

sudo mkdir -p /etc/netns/ns1

ip netns add ns1
ip netns list
ip netns del ns1

ip netns exec ns1 ip link set lo up

ip netns exec ns1 ip route show

ip netns exec ns1 dig -t MX @8.8.8.8 suse.com

<Listing 1>
ip netns exec ns1 bash
ip link set eth1 up
ip addr add 192.168.1.123/24 dev eth1
ip -f inet addr show
exit
<Listing 1>

$ ip netns add ns1
$ ip netns add ns2
$ ip netns list
$ tree /var/run/netns

<Listing 2>
$ mount | grep netns
<Listing 2>

$ ip netns exec ns1 ip link

$ tree /sys/class/net

<Listing 3>
$ ip link set eth1 netns ns1
$ ip netns exec ns1 ip link
<Listing 3>

$ mkdir -pv /etc/netns/ns1
$ echo 1.2.3.4\ mytest | tee /etc/netns/ns1/hosts
$ ip netns exec ns1 getent hosts

<Listing 4>
$ ip netns exec ns1 ip link set lo up
$ ip netns exec ns1 ip link set eth1 up
$ ip netns exec ns1 ip addr add 192.168.1.123/24 dev eth1
$ ip netns exec ns1 ip -f inet addr show
$ ip netns exec ns1 ip route add default via 192.168.1.1 dev eth1
$ ip netns exec ns1 ping -c2 8.8.8.8
<Listing 4>

<Listing 5>
$ ip netns exec ns1 ip link add name veth1 type veth peer name veth2
$ ip netns exec ns1 tree /sys/class/net
$ ip netns exec ns1 ip link set dev veth2 netns ns2
$ ip netns exec ns2 ip link
$ ip netns exec ns1 ip addr add 1.1.1.1/10 dev veth1
$ ip netns exec ns2 ip addr add 1.1.1.2/10 dev veth2
$ ip netns exec ns1 ip link set veth1 up
$ ip netns exec ns2 ip link set veth2 up
$ ip netns exec ns1 ping -c2 1.1.1.2
<Listing 5>

$ ip netns exec ns1 /usr/sbin/sshd -o PidFile=/run/sshd-ns1.pid -o ListenAddress=1.1.1.1

<Listing 6>
$ ps -ef | grep $(cat /run/sshd-ns1.pid)
$ ip netns exec ns1 ss -ltn
<Listing 6>

<Listing 7>
$ ip netns exec ns2 ssh 1.1.1.1
$ ip -f inet addr show
$ ss -etn
<Listing 7>

<Listing 8>
$ ip netns exec ns1 ip link delete veth1
$ ip link add name veth1 type veth peer name veth2
$ ip link
$ ip -f inet addr show eth0
$ ip addr del 192.168.56.130/24 dev eth0
$ brctl addbr br0
$ ip addr add 192.168.56.130/24 dev br0
$ ip link set br0 up
$ ip -f inet addr show br0
$ brctl addif br0 eth0
$ brctl addif br0 veth1
$ brctl show
<Listing 8>


$ ip link set veth2 netns ns1
$ ip netns exec ns1 ip addr add 192.168.56.131/24 dev veth2
$ ip netns exec ns1 ip link set lo up
$ ip netns exec ns1 ip link set veth2 up

$ ip netns exec ns1 ip link delete veth1
$ ip netns exec ns1 ip link set eth1 netns 1
$ ip netns del ns1
$ ip netns del ns2

$ ip netns pids <namespace>

<Listing 9>
$ ps auxww | grep $(ip netns pids ns1)
$ ip netns pids ns1 | xargs kill
$ ip netns del ns1
$ ip netns identify 1445
$ ip netns monitor
<Listing 9>