add option to pick static network

[newns] / newns

diff --git a/newns b/newns
index b45c994987c208e9aa570552e2b8c85987c8c3fe..2896cf21d942162ccfe4d2472af2e962450ad937 100755 (executable)
--- a/newns
+++ b/newns
@@ -38,21 +38,20 @@ fi
 usage() {
     cat <<EOF
 usage: ${0##*/} [OPTS] start|stop NS_NAME
-Setup new or systemd created network namespace with nat and mount namespace
-
--c, --create    Create network namespace. For running outside systemd private net.
+Nat a network namespace. create a mount ns. systemd friendly
+
+-c, --create    Create a named network namespace. When running from
+                the same network namespace as pid 1, this is set automatically.
+                This is the case when running outside a systemd created
+                private network.
+-n NETWORK      x.x.x /24 private network to use. If not specified, uses
+                the first one starting at 10.173.1
 -h, --help      Show this help and exit.
 
 From within a systemd network namespace, nat it to the outside. This
 would be called from ExecStartPre, and or subsequent units called with
 JoinsNamespaceOf= and PrivateNetwork=true.
 
-If given -c, or if in the default network namespace, create a named
-network namepace natted to the current netns.
-
-Uses /24 network, finding the first locally unused one starting at
-10.173.0.
-
 Also create a named mount namespace under /root/mount_namespaces, so we
 can alter some system config for this namespace. Subsequent systemd
 command lines would be prefixed with:
@@ -76,8 +75,8 @@ Background:
 This script does not make the namespace be named like ip does, because
 the naming is not necessary, although it could have been done with some
 more work. For debugging and joining the namespace with a bash shell, I
-use nsenter -n -m -t $(pgrep PROCESS_IN_NAMESPACE).  Note: if I knew how
-to easily ask systemd what pid a unit has, i would do that.
+use nsenter -n -m -t \$(pgrep PROCESS_IN_NAMESPACE) bash.  Note: if I
+knew how to easily ask systemd what pid a unit has, i would do that.
 
 "ip netns new ..." also does a mount namespace, then bind
 mounts each file/dir in /etc/netns/NS_NAME to /etc/NS_NAME. Note,
@@ -95,11 +94,12 @@ EOF
 
 #### begin arg parsing ####
 create=false
-temp=$(getopt -l help,create hc "$@") || usage 1
+temp=$(getopt -l help,create hcn: "$@") || usage 1
 eval set -- "$temp"
 while true; do
     case $1 in
         -c|--create) create=true; shift ;;
+        -n) network=$2; shift 2 ;;
         -h|--help) usage ;;
         --) shift; break ;;
         *) echo "$0: Internal error!" ; exit 1 ;;
@@ -162,10 +162,13 @@ nat() { dexec iptables -t nat $1 POSTROUTING -o $gateway_if -j MASQUERADE \
               -m comment --comment "systemd network namespace nat"; }
 
 find_network() {
+    if [[ $network ]]; then
+        return
+    fi
     found=false
     existing=false
     ips="$(ipd addr show | awk '$1 == "inet" {print $2}')"
-    for ((i=0; i <= 254; i++)); do
+    for ((i=1; i <= 254; i++)); do
         network=$ip_base.$i
         if printf "%s\n" "$ips" | grep "^${network//./\\.}" >/dev/null; then
             existing=true