2 # Copyright (C) 2017 Ian Kelling
4 # Licensed under the Apache License, Version 2.0 (the "License");
5 # you may not use this file except in compliance with the License.
6 # You may obtain a copy of the License at
8 # http://www.apache.org/licenses/LICENSE-2.0
10 # Unless required by applicable law or agreed to in writing, software
11 # distributed under the License is distributed on an "AS IS" BASIS,
12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 # See the License for the specific language governing permissions and
14 # limitations under the License.
17 [[ $EUID == 0 ]] ||
exec sudo
-E "$BASH_SOURCE" "$@"
19 if [[ ! $ERRHANDLE_PATH ]]; then
20 ERRHANDLE_PATH
=$
(readlink
-f "${BASH_SOURCE}")
21 ERRHANDLE_PATH
=$
(readlink
-f ${ERRHANDLE_PATH%/*}/..
/errhandle
)
24 for p
in $ERRHANDLE_PATH/{errcatch-function
,bash-trace-function
}; do
35 trap 'echo "$0:$LINENO:error: \"$BASH_COMMAND\" returned $?" >&2' ERR
40 usage: ${0##*/} [OPTS] start|stop NS_NAME
41 Nat a network namespace. create a mount ns. systemd friendly
43 -c, --create Create a named network namespace. When running from
44 the same network namespace as pid 1, this is set automatically.
45 This is the case when running outside a systemd created
47 -n NETWORK x.x.x /24 private network to use. If not specified, uses
48 the first one starting at 10.173.1
49 -h, --help Show this help and exit.
51 From within a systemd network namespace, nat it to the outside. This
52 would be called from ExecStartPre, and or subsequent units called with
53 JoinsNamespaceOf= and PrivateNetwork=true.
55 Also create a named mount namespace under /root/mount_namespaces, so we
56 can alter some system config for this namespace. Subsequent systemd
57 command lines would be prefixed with:
59 /usr/bin/nsenter --mount=/root/mount_namespaces/NS_NAME
61 Note, this means that they can't run as unpriveledged users, but once
62 systemd 233 comes out, it will have a bind mount option from within unit
63 files, so the mount namespace won't be needed for most use cases, and I
64 will update the script to that the mount namespace not created unless a
65 flag is passed in. Patch welcome to add that flag before then.
67 A recommmended dependency of this script is my other repo named "errhandle",
68 which prints stack trace on error, and calls a cleanup function:
69 https://iankelling.org/git/?p=errhandle, set ERRHANDLE_PATH, or put it
70 in a directory adjacent to the absolute, resolved directory this file is
75 This script does not make the namespace be named like ip does, because
76 the naming is not necessary, although it could have been done with some
77 more work. For debugging and joining the namespace with a bash shell, I
78 use nsenter -n -m -t \$(pgrep PROCESS_IN_NAMESPACE) bash. Note: if I
79 knew how to easily ask systemd what pid a unit has, i would do that.
81 "ip netns new ..." also does a mount namespace, then bind
82 mounts each file/dir in /etc/netns/NS_NAME to /etc/NS_NAME. Note,
83 for openvpn having it's own resolv.conf by using it's user script which
84 calls resolvconf, this doesn't help much. What we actually want to do is
85 copy /run/resolvconf somehwere then bind mount it on top of
88 Please email me if you have a patches, bugs, feedback, or republish this
89 somewhere else: Ian Kelling <ian@iankelling.org>.
95 #### begin arg parsing ####
97 temp
=$
(getopt
-l help,create hcn
: "$@") || usage
1
101 -c|
--create) create
=true
; shift ;;
102 -n) network
=$2; shift 2 ;;
105 *) echo "$0: Internal error!" ; exit 1 ;;
108 if (( $# != 2 )); then
113 nn
=$2 # namespace name
114 #### end arg parsing ####
116 #### begin sanity checking ####
118 if ! type -p ip
&>/dev
/null
; then
119 echo "please install the iproute2 package"
122 if ! type -p iptables
&>/dev
/null
; then
123 echo "please install the iptables package"
126 if $install_error; then
129 #### end sanity checking ####
136 if ! $create && [[ $
(readlink
/proc
/self
/ns
/net
) == "$(readlink /proc/1/ns/net)" ]]; then
140 # make the default network namespace be named
141 target
=/run
/netns
/default
142 if [[ ! -e $target && ! -L $target ]]; then
144 ln -s /proc
/1/ns
/net
$target
148 ipd
() { ip
-n default
"$@"; }
150 ipnn
() { ip
-n $nn "$@"; }
152 # we are already in the network namespace and it's unnamed.
155 dexec
() { ip netns
exec default
"$@"; }
158 # background: head -n1 is defensive. Not sure if there is some weird feature
159 # for 2 routes to be 0/0.
160 gateway_if
=$
(ipd route list exact
0/0 |
head -n1|
sed -r 's/.*\s(\S+)\s*$/\1/')
161 nat
() { dexec iptables
-t nat
$1 POSTROUTING
-o $gateway_if -j MASQUERADE \
162 -m comment
--comment "systemd network namespace nat"; }
165 if [[ $network ]]; then
170 ips
="$(ipd addr show | awk '$1 == "inet
" {print $2}')"
171 for ((i
=1; i
<= 254; i
++)); do
173 if printf "%s\n" "$ips" |
grep "^${network//./\\.}" >/dev
/null
; then
185 echo "$0: error: no open network found"
189 #### begin mount namespace setup ####
190 mkdir
-p /root
/mount_namespaces
191 if ! mountpoint
/root
/mount_namespaces
>/dev
/null
; then
192 mount
--bind /root
/mount_namespaces
/root
/mount_namespaces
193 mount
--make-private /root
/mount_namespaces
195 if [[ ! -e /root
/mount_namespaces
/$nn ]]; then
196 touch /root
/mount_namespaces
/$nn
198 if ! mountpoint
/root
/mount_namespaces
/$nn >/dev
/null
; then
199 # documentation on propagation is a bit weird because it
200 # confusingly talks about binds, namespaces, and mirrors (which
201 # seems to be just another name for bind), shared subtrees
202 # (which seems to a term for binds and namespaces), and does not
203 # properly specify whether the documentation applies to binds,
204 # namespaces, or both. Notably, propagation for binds is marked
205 # on the original mount point, and propagation for a mount
206 # namespace is marked on mounts within the namespace. Here, we
207 # specify that we want mount changes propagated to us, but not
209 unshare
--propagation slave
--mount=/root
/mount_namespaces
/$nn
211 #### end mount namespace setup ####
216 ip
-n $nn link
set dev lo up
219 echo 1 | dexec
dd of
=/proc
/sys
/net
/ipv
4/ip_forward
2>/dev
/null
221 _errcatch_cleanup
=stop
222 ipnn link add
$v0 type veth peer name
$v1
223 ipnn link
set $v0 netns default
224 ipd addr add
$network.1/24 dev
$v0
226 nat
-C &>/dev
/null || nat
-A
227 ipnn addr add
$network.2/24 dev
$v1
229 ipnn route add default via
$network.1
234 if ipd link list
$v0 &>/dev
/null
; then
235 # this also deletes $v1 and the route we added.
240 if nat
-C &>/dev
/null
; then nat
-D; fi
245 if mountpoint
/root
/mount_namespaces
/$nn >/dev
/null
; then
246 umount
/root
/mount_namespaces
/$nn
255 echo "$0: error: unsupported action"