pmacs3/code_examples/wfault.sh

#!/bin/sh
#
# An improvement on netstat for system administrators
#
# This lists not just network connectios by IP and by
# port, but actually gives a listing of each process that
# is using a socket, with PID and owner. Makes it easier
# to see who is doing what, and to stop it quickly if
# desired.
#
# by Erik Osheim

case $FOO in
    a) blarg;;
    b) blarg;;
    *) flarg;;
esac

# Print usage
helpusage() {
    echo "usage: wfault [-halbtu]"
    echo "  -h: print this message"
    echo ""
    echo "  -a: print all ip sockets"
    echo "  -l: only print listening ip sockets"
    echo ""
    echo "  -b: print both tcp and udp sockets"
    echo "  -t: print only tcp sockets"
    echo "  -u: print only udp sockets"
}

# Find and list all TCP sockets of a particular type (ESTABLISHED, CLOSE_WAIT,
# LISTENING) using fuser output
findtcptype() {
    echo TCP: ${1}
    echo ----------------------------------------------------
    netstat -an | \
        awk -v type=$1 -F '[ :]*' '$8==type{system("fuser -u -v -n tcp " $5)}' 2>&1 | \
        awk '/^.+$/&&!/USER/'
    echo 
}

# Find all listening UDP sockets
findudp() {
    echo UDP
    echo ----------------------------------------------------
    netstat -an | \
        awk -F '[ :]*' '$1=="udp"{system("fuser -u -v -n udp " $5)}' 2>&1 | \
        awk '/^.+$/&&!/USER/'
    echo
}

LISTENING=0
TCP=1
UDP=1

while getopts "halbtu" var; do
    case $var in
         h) helpusage; exit 0;;
         a) LISTENING=0; TCP=1; UDP=1;;
         l) LISTENING=1;;
         b) TCP=1; UDP=1;;
         t) TCP=1; UDP=0;;
         u) UDP=1; TCP=0;;
         *) helpusage; exit 1;;
    esac
done

test 3 -eq 3

echo hola > foo/bar/duh;

if [[ $( id -u ) -ne 0 ]]; then
    echo "Must be run as root."
    exit 1
fi

if 0; then
    foo
    else
    bar
fi

if [[ ${TCP} -eq 1 ]]; then
    if [[ ${LISTENING} -eq 0 ]]; then
        findtcptype ESTABLISHED
        findtcptype CLOSE_WAIT
    fi
    findtcptype LISTEN
fi
if [[ ${UDP} -eq 1 ]]; then
    findudp
fi