Add script to rewrite packet captures IP and MAC addresses.

Closes #230.

sbin/rewrite-captures.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+#
+# Rewrite packet captures in order to be able to replay them.
+#
+# SINET:  Rewrite all packets with this source IP address
+# SETHER: Rewrite all packets with this MAC
+#
+# DINET:  Rewrite all packets with this destination IP address
+# DETHER: Rewrite all packets with this destination MAC address
+#
+# The resulting files have the original name with "-rewritten.pcap"
+# appended as a suffix. Those packets may then be replayed from a
+# different computer or virtual container, for instance with:
+#
+# sudo bittwist -i 1 -v -m10 capture-rewritten.pcap
+#
+# Where -i n is the interface name (use bittwist -d to list available
+# interfaces), -v is the verbose flag and -m10 replays at 10× speed.
+#
+
+SINET=${SINET:-$(ip -o -4 addr |grep -v " lo " |head -n 1 |sed -r 's/^.*inet\s([0-9.]+).*$/\1/')}
+SETHER=${SETHER:-$(ip -o link |grep -v " lo" |head -n 1 |sed -r 's/^.*ether\s([0-9a-fA-F:]+).*$/\1/')}
+
+DINET=${DINET:-$(ip -o -4 addr |grep -v " lo " |head -n 1 |sed -r 's/^.*inet\s([0-9.]+).*$/\1/')}
+DETHER=${DETHER:-$(ip -o link |grep -v " lo" |head -n 1 |sed -r 's/^.*ether\s([0-9a-fA-F:]+).*$/\1/')}
+
+for f in $*; do
+
+    OUTFNAME=$f-rewritten.pcap
+    echo $f → $OUTFNAME
+    if [[ -n "$SINET" && -n "$SETHER" ]]; then
+        tcprewrite -S 0.0.0.0/0:$SINET --enet-smac=$SETHER \
+        -D 0.0.0.0/0:$DINET --enet-dmac=$DETHER \
+        --infile "$f" \
+        --outfile "$OUTFNAME"
+    else
+        tcprewrite  -D 0.0.0.0/0:$DINET --enet-dmac=$DETHER \
+        --infile "$f" \
+        --outfile "$OUTFNAME"
+    fi
+
+done