k8s/StudyNotes/ k8sNetworking

• Linux network namespaces

  ip netns add red
  ip netns add blue
  ip netns list
  ip netns exec red ip link
  ip netns exec red arp
  ip netns exec red route

• Connect two network namespaces with virtual link

  ip link add veth-red type veth peer name veth-blue
  ip link set veth-red  netns red
  ip link set veth-blue netns blue
  ip -n red  addr add 192.168.15.1 dev veth-red
  ip -n blue addr add 192.168.15.2 dev veth-blue
  ip -n red  link set veth-red  up
  ip -n blue link set veth-blue up
  #
  ip netns exec red ping 192.168.15.2

• create bridge to scale,

  ip link add v-net-0 type bridge
  ip link 
  ip link set dev v-net-0 up

• remove red-blue link and reconnect to bridge/switch

  ip -n red link del veth-red
  #
  ip link add veth-red  type veth peer name veth-red-br
  ip link add veth-blue type veth peer name veth-blue-br
  #
  ip link set veth-red netns red
  ip link set veth-red-br master v-net-0
  #
  ip link set veth-blue netns blue
  ip link set veth-blue-br master v-net-0
  #
  ip -n red  addr add 192.168.15.1/24 dev veth-red
  ip -n blue addr add 192.168.15.2/24 dev veth-blue
  #
  ip -n red link

• From host can assign ip to bridge interface

  ip addr add 192.168.15.15/24 dev v-net-0
  #
  # can add route to other namespaces for outbound routing
  ip netns exec blue ip ruote add 0.0.0.0/0 via 192.168.15.15

• Masquerade namespace traffic outbound

  iptables -t nat -A POSTROUTING -s 192.168.15.0/24 -j MASQUERADE