#!/bin/ksh

#
# ports
#
# Show network sockets with their owning processes.
#
# Similar idea to Linux:
#
#     netstat -tulpn
#
# OpenBSD implementation using:
#
#     fstat
#     ps
#
# Run as root for complete information.
#


# ------------------------------------------------------------
# Header
# ------------------------------------------------------------

printf "%-5s %-28s %-8s %-12s %s\n" \
    "PROTO" \
    "LOCAL ADDRESS" \
    "PID" \
    "USER" \
    "COMMAND"

printf "%-5s %-28s %-8s %-12s %s\n" \
    "-----" \
    "----------------------------" \
    "--------" \
    "------------" \
    "-------"


# ------------------------------------------------------------
# Read Internet sockets from fstat
# ------------------------------------------------------------

fstat 2>/dev/null |
awk '
    #
    # We only want IPv4/IPv6 Internet sockets.
    #
    $5 == "internet" || $5 == "internet6" {

        user    = $1
        process = $2
        pid     = $3
        family  = $5
        type    = $6
        proto   = $7

        #
        # Ignore raw sockets.
        #
        if (type != "stream" && type != "dgram")
            next

        #
        # Only TCP and UDP.
        #
        if (proto != "tcp" && proto != "udp")
            next


        #
        # Determine tcp4/tcp6/udp4/udp6.
        #
        if (family == "internet6")
            proto = proto "6"
        else
            proto = proto "4"


        #
        # Find the local address.
        #
        # fstat output contains a kernel socket pointer before
        # TCP addresses, for example:
        #
        #   tcp 0xffff800001058140 *:22
        #
        # UDP normally looks like:
        #
        #   udp 192.168.0.2:37163 <-> ...
        #
        # Search fields after the protocol for the first field
        # containing ":".
        #

        local = "-"

        for (i = 8; i <= NF; i++) {

            if ($i ~ /:/) {
                local = $i
                break
            }
        }


        #
        # Print fields separated by tabs so the shell can
        # safely parse them.
        #
        printf "%s\t%s\t%s\t%s\n",
            proto,
            local,
            pid,
            user
    }
' |
while IFS='	' read proto local pid user
do

    # --------------------------------------------------------
    # Get complete command line from PID.
    # --------------------------------------------------------

    command="$(
        ps -p "$pid" -o args= 2>/dev/null
    )"

    if [ -z "$command" ]; then
        command="-"
    fi


    # --------------------------------------------------------
    # Output
    # --------------------------------------------------------

    printf "%-5s %-28s %-8s %-12s %s\n" \
        "$proto" \
        "$local" \
        "$pid" \
        "$user" \
        "$command"

done