ifupdown-netns

Some simple scripts to simplify configuring network namespaces on Debian-like systems. Copy them into the corresponding directories under /etc/network.

To configure an interface in a namespace:

auto eth1
iface eth1 inet manual
  netns myns

On invocation of ifup:

• if the namespace doesn't exist it will be created
• if the folders if-down.d, if-post-down.d, if-pre-up.d and if-up.d under /etc/netns/<namespace>/network don't exist, they will be created
• if the /etc/netns/<namespace>/network/interfaces file doesn't exist a blank one will be created
• if it does and the interface is configured, the script will invoke ifup for this interface inside the namespace.

zsh functions to run commands and start a shell in a namespace with a custom prompt

nse () {
  if [ $# -lt 2 ]; then
    echo "Please specify a network namespace and a command"
    echo "Usage: $0 <namespace> <command>"
    return
  fi
  NS=${1}
  shift
  ARGS=${@}
  ip netns exec ${NS} unshare -m /bin/sh -c "mount --make-rprivate /;mount --bind /run/network.${NS} /run/network; ${ARGS}"
}

nss () {
  if [ $# -ne 1 ]; then
    echo "Please specify a network namespace"
    echo "Usage: $0 <namespace>"
    return
  fi
  nse $1 zsh -i
}

alias nsr="nsenter -t 1 -n"

NS=`ip netns identify $$`

if [ "$NS" ]; then;
  NS="/$NS"
fi

if [ "`id -u`" -eq 0 ]; then
  export PS1="%{%}%T%{%} %{%}%n%{%}@%{%}%m${NS} %{%}%~%{%}%#%{%} "
else
  export PS1="%{%}%T%{%} %{%}%n%{%}@%{%}%m${NS} %{%}%~%{%}%#%{%} "
fi