xt_pknock: import digest generation utility

extensions/pknock/knock.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+# $1 -> IP src
+# $2 -> IP dst
+# $3 -> PORT dst
+# $4 -> secret
+
+if [ -z $4 ]; then 
+    echo "usage: $0 <IP src> <IP dst> <PORT dst> <secret>"
+    exit 1
+fi
+
+digest_file="/tmp/digest.txt"
+
+python ../test/py/gen_hmac.py $4 $1 > $digest_file
+nemesis udp -S $1 -D $2 -y $3 -P $digest_file