Part II of network scripts. Back-routing behing FW

set_routes.sh

#! /bin/bash

IFNAME=${1}

NIC_IPNR=$(ifconfig | \
        grep $IFNAME -A3 | \
        grep "inet addr" | \
        cut -f2 -d":" | \
        cut -f1 -d " ")
LNET=$(echo $NIC_IPNR | cut -f1-3 -d".").0
GW=$(echo $NIC_IPNR | cut -f1-3 -d".").1

source logger.sh

if [ "X$IFNAME" == "X" ]; then
        logger "First argument (IFNAME) must be present. Exiting..."
        exit 1
fi

if [ "X$NIC_IPNR" == "X" ]; then
        logger "IF [$IFNAME] not up or doesn't exist. Exiting..."
        exit 1
fi

logger "$(basename $0): Setting up return-route for IF: [$IFNAME]"
logger "   NIC: [$NIC_IPNR]"
logger "   NET: [$LNET]"
logger "    GW: [$GW]"

#Check if there exist a specific table for the interface
EXIST_TABLE=$(cat /etc/iproute2/rt_tables | \
        grep -Ev '^#' | \
        grep $IFNAME)

OTHER_TABLE_IDS=$(cat /etc/iproute2/rt_tables | \
        grep -Ev '^#' | \
        grep -vE 'local|main|default|unspec' | \
        cut -f1 -d" " | \
        sort -n)

NEXT_ID=$(( $((sed -e 's/[[:space:]]\+/\n/g' |  tail -n1) <<< $OTHER_TABLE_IDS) + 1))

if [ "X${EXIST_TABLE}" == "X" ]; then
        logger "Table missing for interface [$IFNAME]. Creating one as ID [$NEXT_ID]"
        echo "$NEXT_ID $IFNAME" >> /etc/iproute2/rt_tables
fi
logger ">>> Table:"
cat /etc/iproute2/rt_tables | \
        grep -Ev '^#' | \
        grep $IFNAME | \
                logger

if [ "X$(ip route show table ${IFNAME})" == "X" ]; then
        logger "Table is not set, setting"
        ip route add $LNET/24 dev $IFNAME src $NIC_IPNR table $IFNAME | logger
        ip route add default via $GW dev $IFNAME table $IFNAME | logger
fi
logger ">>> Routes in table [${IFNAME}]:"
ip route show table ${IFNAME} | logger

if [ "X$(ip rule | grep  $IFNAME)" == "X" ]; then
        logger "Rule is not set, settig"
        ip rule add from $NIC_IPNR/32 table $IFNAME | logger
        ip rule add to $NIC_IPNR/32 table $IFNAME | logger
fi
logger ">>> Rules fo table [${IFNAME}]:"
ip rule | grep  $IFNAME | logger