ipsearch

#! /usr/bin/env python3

# Search for IP clients on the current network.
# Only tested on Linux; requires ping or the Linux arguments for arp.
# ipsearch with no arguments uses ping; it takes a while but should be reliable.
# ipsearch -a uses arp only, which is fast but only shows
# hosts in the arp cache.

import sys
import subprocess
import socket
import fcntl
import struct
import re
import argparse

try:
    from arpreq import arpreq
except:
    arpreq = None

try:
    from mac_lookup import match_mac
except:
    match_mac = None

# Some globals
g_debugging = False
g_can_ping = True
g_can_arp = True

def ping(host):
    """Ping a host by name or address.
       Return True if it answers, False otherwise.
       If ping doesn't exist on the machine, raises FileNotFoundError.
    """
    if not g_can_ping:
        return False

    rv = subprocess.call(["ping", "-q", "-c", "1", "-W", "1", host],
                         stdout = subprocess.PIPE,
                         stderr = subprocess.PIPE)
    if rv == 0:
        return True
    return False

def fping(network):
    """Ping all hosts on the given network.
       Return a list of the hosts that responded.
       Raises FileNotFoundError if fping isn't installed.
    """
    proc = subprocess.Popen(["fping", "-c1", "-t1000"]
                            + [ network + '.'
                                + str(i) for i in range(1,256) ],
                            stdout = subprocess.PIPE,
                            stderr = subprocess.PIPE)
    proc_out = proc.communicate()

    # Now proc_out[0].decode("utf-8") contains lines like
    # 192.168.1.1  : [0], 84 bytes, 0.42 ms (0.42 avg, 0% loss)
    # for everything that actually did respond.
    #
    # proc_out[0].decode("utf-8") contains stats about all hosts,
    # 192.168.1.1  : xmt/rcv/%loss = 1/1/0%, min/avg/max = 0.42/0.42/0.42
    # 192.168.1.2  : xmt/rcv/%loss = 1/0/100%

    hits = []
    for line in proc_out[0].decode("utf-8").split('\n'):
        match = re.match(r'([0-9]{1,3}[\.]){3}([0-9]{1,3})', line)
        if match:
            hits.append(match.group())
    return hits

def arp(host):
    """Call arp -a on an address.
       Return the MAC if it answers, None if it doesn't.
       If arp doesn't exist on the machine, raises FileNotFoundError.
    """
    if arpreq:
        return arpreq(host)

    if not g_can_arp:
        print("can't arp, skipping", host)
        return False

    proc = subprocess.Popen(["arp", "-a", host],
                            stdout = subprocess.PIPE,
                            stderr = subprocess.PIPE)
    proc_out = proc.communicate()[0].strip()
    if b"no match found" in proc_out:
        # print("no match found, returning none")
        return None
    # else:
    #     print("'no match found' isn't in '%s'" % proc_out)
    if b"<incomplete>" in proc_out:
        return None

    match = re.search(b'([0-9A-F]{2}[:-]){5}([0-9A-F]{2})', proc_out, re.I)
    if match:
        return match.group().decode("utf-8")
    return None

def check_port(host, port):
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.settimeout(.25)
    result = sock.connect_ex((host, port))
    sock.close()
    return not result

def net_interfaces():
    ifaces = []
    with open("/proc/net/dev") as fp:
        for line in fp:
            match = re.search('([a-z0-9]+): ', line)
            if match:
                iface = match.group(1)
                if not iface.startswith('lo'):
                    ifaces.append(iface)
    return ifaces

def ip_addr(iface):
    """Get the IP address of the interface (e.g. eth0)
    """
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    info = fcntl.ioctl(s.fileno(),
                       0x8915,  # SIOCGIFADDR
                       struct.pack('256s', bytes(iface[:15], "utf-8")))
    return socket.inet_ntoa(info[20:24])

def scan(iface, port=None):
    """Scan all hosts on the network specified by the interface iface.
       This is not smart about network classes: it will replace the
       final number in the dotted quad with 1-255.
    """
    myip = ip_addr(iface)
    mynetwork = '.'.join(myip.split('.')[0:3])

    if (g_debugging):
        print("My IP is", myip, "on", iface)
        print("My network is", mynetwork)
        print()

    fmt = "%15s %18s %12s %s"

    # Use fping to ping all hosts
    try:
        pinghosts = fping(mynetwork)
        ping_separately = False
    except FileNotFoundError:
        print("Couldn't fping, will have to ping all hosts separately")
        pinghosts = [ mynetwork + '.' + str(i) for i in range(1,256) ]
        ping_separately = True

    for hostip in pinghosts:  # I know, it should adjust based on net class
        # hostip = "%s.%d" % (mynetwork, h)

        if g_debugging:
            print(hostip, end='\r')
            sys.stdout.flush()

        if port:
            if not check_port(hostip, port):
                continue

        if ping_separately:
            pingout = ping(hostip)
            if not pingout:
                continue

        mac = arp(hostip)
        if not mac:
            continue

        if match_mac:
            oui = match_mac(mac)
        else:
            oui = ''

        try:
            hostname, blah1, blah2 = socket.gethostbyaddr(hostip)
        except:
            hostname = '--'

        if hostip == myip:
            print(fmt % (hostip, mac, hostname, oui), "(that's me)")
        else:
            print(fmt % (hostip, mac, hostname, oui))

def net_interfaces():
    ifaces = []
    with open("/proc/net/dev") as fp:
        for line in fp:
            match = re.search('([a-z0-9]+): ', line)
            if match:
                iface = match.group(1)
                if not iface.startswith('lo'):
                    ifaces.append(iface)
    return ifaces

if __name__ == "__main__":
    def Usage():
        print("""Usage: %s [-a] [-p]
-p: ping each host first, in case they weren't in the arp cache already
-a: Use arp -a to ping.
""" % sys.argv[0])
        sys.exit(1)

    parser = argparse.ArgumentParser()

    parser.add_argument('-d', "--debug", dest="debug", default=False,
                        action="store_true", help="Verbose debugging")

    parser.add_argument('-p', action="store", dest="port", type=int,
                        default=None, help='Check if this port is open')

    args = parser.parse_args(sys.argv[1:])
    if args.debug:
        g_debugging = True

    ifaces = net_interfaces()
    if g_debugging:
        print("Net interfaces:", ' '.join(ifaces))

    myip = None

    for iface in ifaces:
        try:
            myip = ip_addr(iface)
            break
        except OSError:
            continue

    if not myip:
        print("Couldn't find my IP address", file=sys.stderr)
        sys.exit(1)

    # Can we ping or arp?
    try:
        g_can_ping = bool(ping(myip))
    except FileNotFoundError:
        print("Can't ping", file=sys.stderr)
        # sys.exit(1)

    if not arpreq:
        try:
            arpout = arp(myip)
            if g_debugging:
                print("Will use individual arp calls")
        except FileNotFoundError:
            print("Can't arp", file=sys.stderr)
            g_can_arp = False
            sys.exit(1)
    elif g_debugging:
        print("Using arpreq library")

    ifaces = net_interfaces()
    if g_debugging:
        print("Net interfaces:", ' '.join(ifaces))

    myip = None

    for iface in ifaces:
        try:
            myip = ip_addr(iface)
            break
        except OSError:
            continue

    if not myip:
        print("Couldn't find my IP address")
        sys.exit(1)

    try:
        scan(iface, port=args.port)

    except KeyboardInterrupt:
        print("Interrupt")