--- /dev/null
+
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--- /dev/null
+#!/bin/bash
+# Copyright (C) 2017 Ian Kelling
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+# http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+# Create a network namespace. Designed for use from systemd.
+
+[[ $EUID == 0 ]] || exec sudo -E "$BASH_SOURCE" "$@"
+
+cd "${BASH_SOURCE%/*}"
+source ../errhandle/errcatch-function
+source ../errhandle/bash-trace-function
+errcatch
+
+
+## begin arg parsing ##
+action=$1
+nn=$2 # network namespace / namespace name
+## end arg parsing ##
+
+## begin sanity checking ##
+
+install_error=false
+if ! type -p ip &>/dev/null; then
+ echo "please install the iproute2 package"
+ install_error=true
+fi
+if ! type -p iptables &>/dev/null; then
+ echo "please install the iptables package"
+ install_error=true
+fi
+if $install_error; then
+ exit 1
+fi
+
+## end sanity checking ##
+
+
+v0=veth0-$nn
+v1=veth1-$nn
+ip_base=10.173
+
+
+target=/run/netns/default
+if [[ ! -e $target && ! -L $target ]]; then
+ mkdir -p /run/netns
+ # make the default network namespace be named
+ ln -s /proc/1/ns/net $target
+fi
+
+
+ipd() { ip -n default "$@"; }
+dexec() { ip netns exec default "$@"; }
+
+# note: this script could be easily adapted to create a
+# netns instead of using the systemd created one.
+# ip netns add NAME
+# ip -n NAME link set dev lo up
+
+# random note, ip netns exec creates a mount namespace and
+# remaps /etc to /etc/netns/NAME.
+
+# head -n1 is defensive. I don't know if it's possible to have more
+# than one default route.
+gateway_if=$(ipd route list exact 0/0 | head -n1| sed -r 's/.*\s(\S+)\s*$/\1/')
+nat() { dexec iptables -t nat $1 POSTROUTING -o $gateway_if -j MASQUERADE \
+ -m comment --comment "systemd network namespace nat"; }
+
+find_network() {
+ found=false
+ existing=false
+ ips="$(ipd addr show | awk '$1 == "inet" {print $2}')"
+ for ((i=0; i <= 254; i++)); do
+ network=$ip_base.$i
+ if printf "%s\n" "$ips" | grep "^${network//./\\.}"; then
+ existing=true
+ else
+ found=true
+ break
+ fi
+ done
+}
+
+start() {
+
+ mkdir -p /root/mount_namespaces
+ if ! mountpoint /root/mount_namespaces >/dev/null; then
+ mount --bind /root/mount_namespaces /root/mount_namespaces
+ mount --make-private /root/mount_namespaces
+ fi
+ if [[ ! -e /root/mount_namespaces/$nn ]]; then
+ touch /root/mount_namespaces/$nn
+ fi
+ if ! mountpoint /root/mount_namespaces/$nn >/dev/null; then
+ unshare --mount=/root/mount_namespaces/$nn
+ fi
+
+
+
+ find_network
+ if ! $found; then
+ echo "$0: error: no open network found"
+ exit 1
+ fi
+
+ echo 1 | dexec dd of=/proc/sys/net/ipv4/ip_forward 2>/dev/null
+
+ _errcatch_cleanup=stop
+ ip link add $v0 type veth peer name $v1
+ ip link set $v0 netns default
+ ipd addr add $network.1/24 dev $v0
+ ipd link set $v0 up
+ nat -C &>/dev/null || nat -A
+ ip addr add $network.2/24 dev $v1
+ ip link set $v1 up
+ ip route add default via $network.1
+
+}
+
+stop() {
+ if ipd link list $v0 &>/dev/null; then
+ # this also deletes $v1 and the route we added.
+ ipd link del $v0
+ fi
+ find_network
+ if ! $existing; then
+ if nat -C &>/dev/null; then nat -D; fi
+ fi
+}
+
+case $action in
+ start|stop)
+ $action
+ ;;
+ *)
+ echo "$0: error: unsupported action"
+ exit 1
+ ;;
+esac
iankelling.org / git / newns / commitdiff