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. systemd friendly
43 Also creates a mount namespace with a cloned /etc/resolv.conf.
45 -c, --create Create a named network namespace. When running from
46 the same network namespace as pid 1, this is set automatically.
47 This is the case when running outside a systemd created
49 -n NETWORK x.x.x /24 private network to use. If not specified, uses
50 the first one starting at 10.173.1
51 -h, --help Show this help and exit.
53 From within a systemd network namespace, nat it to the outside. This
54 would be called from ExecStartPre, and or subsequent units called with
55 JoinsNamespaceOf= and PrivateNetwork=true.
57 Also create a named mount namespace under /root/mount_namespaces, so we
58 can alter some system config for this namespace. Subsequent systemd
59 command lines would be prefixed with:
61 /usr/bin/nsenter --mount=/root/mount_namespaces/NS_NAME
63 Note, this means that they can't run as unpriveledged users, but once
64 systemd 233 comes out, it will have a bind mount option from within unit
65 files, so the mount namespace won't be needed for most use cases, and I
66 will update the script to that the mount namespace not created unless a
67 flag is passed in. Patch welcome to add that flag before then.
69 A recommmended dependency of this script is my other repo named "errhandle",
70 which prints stack trace on error, and calls a cleanup function:
71 https://iankelling.org/git/?p=errhandle, set ERRHANDLE_PATH, or put it
72 in a directory adjacent to the absolute, resolved directory this file is
77 This script does not make the namespace be named like ip does, because
78 the naming is not necessary, although it could have been done with some
79 more work. For debugging and joining the namespace with a bash shell, I
80 use nsenter -n -m -t \$(pgrep PROCESS_IN_NAMESPACE) bash. Note: if I
81 knew how to easily ask systemd what pid a unit has, i would do that.
83 "ip netns new ..." also does a mount namespace, then bind
84 mounts each file/dir in /etc/netns/NS_NAME to /etc/NS_NAME. Note,
85 for openvpn having it's own resolv.conf by using it's user script which
86 calls resolvconf, this doesn't help much. What we actually want to do is
87 copy /run/resolvconf somehwere then bind mount it on top of
90 Please email me if you have a patches, bugs, feedback, or republish this
91 somewhere else: Ian Kelling <ian@iankelling.org>.
97 #### begin arg parsing ####
99 temp
=$
(getopt
-l help,create hcn
: "$@") || usage
1
103 -c|
--create) create
=true
; shift ;;
104 -n) network
=$2; shift 2 ;;
107 *) echo "$0: Internal error!" ; exit 1 ;;
110 if (( $# != 2 )); then
115 nn
=$2 # namespace name
116 #### end arg parsing ####
118 #### begin sanity checking ####
120 if ! type -p ip
&>/dev
/null
; then
121 echo "please install the iproute2 package"
124 if ! type -p iptables
&>/dev
/null
; then
125 echo "please install the iptables package"
128 if $install_error; then
131 #### end sanity checking ####
138 if ! $create && [[ $
(readlink
/proc
/self
/ns
/net
) == "$(readlink /proc/1/ns/net)" ]]; then
142 # make the default network namespace be named
143 target
=/run
/netns
/default
144 if [[ ! -e $target && ! -L $target ]]; then
146 ln -s /proc
/1/ns
/net
$target
150 ipd
() { ip
-n default
"$@"; }
152 ipnn
() { ip
-n $nn "$@"; }
154 # we are already in the network namespace and it's unnamed.
157 dexec
() { ip netns
exec default
"$@"; }
160 # background: head -n1 is defensive. Not sure if there is some weird feature
161 # for 2 routes to be 0/0.
162 gateway_if
=$
(ipd route list exact
0/0 |
head -n1|
sed -r 's/.*dev\s+(\S+).*/\1/')
163 nat
() { dexec iptables
-t nat
$1 POSTROUTING
-o $gateway_if -j MASQUERADE \
164 -m comment
--comment "systemd network namespace nat"; }
167 if [[ $network ]]; then
172 ips
="$(ipd addr show | awk '$1 == "inet
" {print $2}')"
173 for ((i
=1; i
<= 254; i
++)); do
175 if printf "%s\n" "$ips" |
grep "^${network//./\\.}" >/dev
/null
; then
187 echo "$0: error: no open network found"
191 #### begin mount namespace setup ####
192 mkdir
-p /root
/mount_namespaces
193 if ! mountpoint
/root
/mount_namespaces
>/dev
/null
; then
194 mount
--bind /root
/mount_namespaces
/root
/mount_namespaces
196 # note: This is outside the mount condition because I've mysteriously
197 # had this become shared instead of private, perhaps it
198 # got remounted somehow and lost the setting.
199 mount
--make-private /root
/mount_namespaces
200 if [[ ! -e /root
/mount_namespaces
/$nn ]]; then
201 touch /root
/mount_namespaces
/$nn
203 if ! mountpoint
/root
/mount_namespaces
/$nn >/dev
/null
; then
204 # documentation on propagation is a bit weird because it
205 # confusingly talks about binds, namespaces, and mirrors (which
206 # seems to be just another name for bind), shared subtrees
207 # (which seems to a term for binds and namespaces), and does not
208 # properly specify whether the documentation applies to binds,
209 # namespaces, or both. Notably, propagation for binds is marked
210 # on the original mount point, and propagation for a mount
211 # namespace is marked on mounts within the namespace. Here, we
212 # specify that we want mount changes propagated to us, but not
214 unshare
--propagation slave
--mount=/root
/mount_namespaces
/$nn
216 #### end mount namespace setup ####
221 ip
-n $nn link
set dev lo up
224 echo 1 | dexec
dd of
=/proc
/sys
/net
/ipv
4/ip_forward
2>/dev
/null
226 _errcatch_cleanup
=stop
227 ipnn link add
$v0 type veth peer name
$v1
228 ipnn link
set $v0 netns default
229 ipd addr add
$network.1/24 dev
$v0
231 nat
-C &>/dev
/null || nat
-A
232 ipnn addr add
$network.2/24 dev
$v1
234 ipnn route add default via
$network.1
239 if ipd link list
$v0 &>/dev
/null
; then
240 # this also deletes $v1 and the route we added.
245 if nat
-C &>/dev
/null
; then nat
-D; fi
250 if mountpoint
/root
/mount_namespaces
/$nn >/dev
/null
; then
251 umount
/root
/mount_namespaces
/$nn
260 echo "$0: error: unsupported action"