netsonsole

netsonsole

#!/bin/bash
set -e

die() { echo >&2 "$@" ; exit 1 ; }

TGT_IP="$1"
TGT_PORT=${2:-6666}

if [ -z "$TGT_IP" ] ; then
   TTY=${SSH_TTY#/dev/}
   [ -n "$TTY" ] || die "IP not specified, could not get ssh TTY"

   TGT_IP="$( who --ips | awk '$2 == "'"$TTY"'" { print $5 }' )"
   [ -n "$TGT_IP" ] || die "IP not specified, could not figure it out"

   echo >&2 "using target IP $TGT_IP"
fi

ping -q -W1 -c1 "$TGT_IP" >/dev/null 2>&1
VIA_IP="$(ip --oneline route get $TGT_IP | sed -r -n -e 's/.*via ([^ ]+) .*/\1/p;q')"
[ -n "$VIA_IP" ] && ping -q -W1 -c1 "$VIA_IP" >/dev/null 2>&1
TGT_MAC="$(ip --oneline neigh show "${VIA_IP:-$TGT_IP}" | awk '/REACHABLE|STALE|DELAY/{ print $5 }')"
SRC_IP="$(ip --oneline route get $TGT_IP | sed -rne 's/.*src //; s/ .*//p')"
SRC_DEV="$(ip --oneline route get $TGT_IP | sed -rne 's/.*dev //; s/ .*//p')"

echo "TGT_IP=$TGT_IP"
echo "VIA_IP=$VIA_IP"
echo "TGT_MAC=$TGT_MAC"
echo "SRC_IP=$SRC_IP"
echo "SRC_DEV=$SRC_DEV"

ID=$(id -u)
SUDO=
[ "$ID" = 0 ] || SUDO=sudo

if lsmod | grep -q netconsole ; then
   $SUDO rmmod netconsole
fi
(
set -x
$SUDO dmesg -n 8
$SUDO modprobe netconsole "netconsole=6666@$SRC_IP/$SRC_DEV,$TGT_PORT@$TGT_IP/$TGT_MAC"
)
echo DONE