#!/bin/ksh

# OpenBSD equivalent-ish to:
#
#   Linux: netstat -tulpn
#
# Shows listening TCP sockets and UDP sockets together with
# the process using the socket when fstat can identify it.
#
# Best run as root for complete process information.

printf "%-5s %-7s %-8s %-22s %-22s %s\n" \
    "PROTO" "PID" "USER" "LOCAL ADDRESS" "FOREIGN ADDRESS" "PROCESS"

printf "%-5s %-7s %-8s %-22s %-22s %s\n" \
    "-----" "-------" "--------" "----------------------" \
    "----------------------" "-------"

# ------------------------------------------------------------
# TCP listening sockets
# ------------------------------------------------------------

netstat -an -f inet 2>/dev/null |
awk '$1 ~ /^tcp/ && $6 == "LISTEN" {
    print $1, $4, $5
}' |
while read proto local foreign
do
    # Extract port from local address.
    port="${local##*.}"

    # Try to find the process owning this socket.
    owner="$(
        fstat 2>/dev/null |
        awk -v port="$port" '
            $0 ~ ("\\*:" port "([^0-9]|$)") ||
            $0 ~ ("\\." port "([^0-9]|$)") {
                print $1, $2, $3
                exit
            }
        '
    )"

    if [ -n "$owner" ]; then
        set -- $owner

        user="$1"
        process="$2"
        pid="$3"
    else
        user="-"
        process="-"
        pid="-"
    fi

    printf "%-5s %-7s %-8s %-22s %-22s %s\n" \
        "$proto" "$pid" "$user" "$local" "$foreign" "$process"
done


# ------------------------------------------------------------
# UDP sockets
# ------------------------------------------------------------

netstat -an -f inet 2>/dev/null |
awk '$1 ~ /^udp/ {
    print $1, $4, $5
}' |
while read proto local foreign
do
    port="${local##*.}"

    owner="$(
        fstat 2>/dev/null |
        awk -v port="$port" '
            $0 ~ ("\\*:" port "([^0-9]|$)") ||
            $0 ~ ("\\." port "([^0-9]|$)") {
                print $1, $2, $3
                exit
            }
        '
    )"

    if [ -n "$owner" ]; then
        set -- $owner

        user="$1"
        process="$2"
        pid="$3"
    else
        user="-"
        process="-"
        pid="-"
    fi

    printf "%-5s %-7s %-8s %-22s %-22s %s\n" \
        "$proto" "$pid" "$user" "$local" "$foreign" "$process"
done