Provided by: arp-scan_1.8.1-1_amd64 bug

NAME

       arp-scan - The ARP scanner

SYNOPSIS

       arp-scan [options] [hosts...]

       Target  hosts  must be specified on the command line unless the --file option is given, in
       which case the targets are read from the specified file instead, or the --localnet  option
       is used, in which case the targets are generated from the network interface IP address and
       netmask.

       You will need to be root, or arp-scan must be SUID root, in order to run arp-scan, because
       the functions that it uses to read and write packets require root privilege.

       The  target hosts can be specified as IP addresses or hostnames.  You can also specify the
       target as IPnetwork/bits (e.g. 192.168.1.0/24) to specify all hosts in the  given  network
       (network  and broadcast addresses included), IPstart-IPend (e.g. 192.168.1.3-192.168.1.27)
       to  specify   all   hosts   in   the   inclusive   range,   or   IPnetwork:NetMask   (e.g.
       192.168.1.0:255.255.255.0) to specify all hosts in the given network and mask.

DESCRIPTION

       arp-scan  sends  ARP packets to hosts on the local network and displays any responses that
       are received. The network interface to use can be specified with the  --interface  option.
       If  this  option  is  not  present, arp-scan will search the system interface list for the
       lowest numbered, configured up  interface  (excluding  loopback).   By  default,  the  ARP
       packets  are  sent  to  the Ethernet broadcast address, ff:ff:ff:ff:ff:ff, but that can be
       changed with the --destaddr option.

       The target hosts to scan may be specified in one of three ways: by specifying the  targets
       on  the  command line; by specifying a file containing the targets with the --file option;
       or by specifying the --localnet option which causes all  possible  hosts  on  the  network
       attached  to  the  interface (as defined by the interface address and mask) to be scanned.
       For hosts specified on the command line, or with the --file option, you can use either  IP
       addresses  or hostnames.  You can also use network specifications IPnetwork/bits, IPstart-
       IPend, or IPnetwork:NetMask.

       The list of target hosts is stored in memory.  Each host in this list  uses  28  bytes  of
       memory,  so  scanning a Class-B network (65,536 hosts) requires about 1.75MB of memory for
       the list, and scanning a Class-A (16,777,216 hosts) requires about 448MB.

       arp-scan supports Ethernet and 802.11 wireless networks. It could also support token  ring
       and  FDDI,  but they have not been tested. It does not support serial links such as PPP or
       SLIP, because ARP is not supported on them.

       The ARP protocol is a layer-2 (datalink layer) protocol that is used to determine a host's
       layer-2  address  given its layer-3 (network layer) address. ARP was designed to work with
       any layer-2 and layer-3 address format, but the most common use is to map IP addresses  to
       Ethernet  hardware addresses, and this is what arp-scan supports. ARP only operates on the
       local network, and cannot be routed. Although the ARP protocol makes use of IP  addresses,
       it  is  not  an  IP-based  protocol  and  arp-scan can be used on an interface that is not
       configured for IP.

       ARP is only used by IPv4 hosts. IPv6 uses  NDP  (neighbour  discovery  protocol)  instead,
       which is a different protocol and is not supported by arp-scan.

       One  ARP  packet  is  sent for each for each target host, with the target protocol address
       (the ar$tpa field) set to the IP address of this host. If a host does  not  respond,  then
       the  ARP  packet  will be re-sent once more.  The maximum number of retries can be changed
       with the --retry option.  Reducing the number of retries will reduce the scanning time  at
       the possible risk of missing some results due to packet loss.

       You can specify the bandwidth that arp-scan will use for the outgoing ARP packets with the
       --bandwidth option.  By default, it uses a bandwidth of 256000 bits per second. Increasing
       the bandwidth will reduce the scanning time, but setting the bandwidth too high may result
       in an ARP storm which can disrupt network operation.  Also, setting the bandwidth too high
       can  send  packets  faster  than  the  network  interface  can  transmit  them, which will
       eventually fill the kernel's transmit buffer resulting in the  error  message:  No  buffer
       space  available.   Another  way  to  specify  the  outgoing  ARP  packet rate is with the
       --interval option, which is an alternative way to modify the same underlying parameter.

       The time taken to perform a single-pass scan (i.e. with --retry=1) is given by:

       time = n*i + t + o

       Where n is the number of hosts in the  list,  i  is  the  time  interval  between  packets
       (specified  with  --interval,  or  calculated  from  --bandwidth),  t is the timeout value
       (specified with --timeout) and o is the overhead time taken to load the targets  into  the
       list  and  read the MAC/Vendor mapping files.  For small lists of hosts, the timeout value
       will dominate, but for large lists the packet interval is the most important value.

       With 65,536 hosts, the default bandwidth of 256,000 bits/second (which results in a packet
       interval  of  2ms),  the  default  timeout  of  100ms, and a single pass ( --retry=1), and
       assuming an overhead of 1 second, the scan would take 65536*0.002 +  0.1  +  1  =  132.172
       seconds, or about 2 minutes 12 seconds.

       Any  part  of  the  outgoing  ARP  packet  may  be modified through the use of the various
       --arpXXX options.  The use of some of these options may make the outgoing ARP  packet  non
       RFC  compliant. Different operating systems handle the various non standard ARP packets in
       different ways, and this may be used to fingerprint these systems.  See arp-fingerprint(1)
       for  information  about  a  script  which  uses  these  options  to fingerprint the target
       operating system.

       The table below summarises the options that change the outgoing ARP packet. In this table,
       the  Field  column gives the ARP packet field name from RFC 826, Bits specifies the number
       of bits in the field, Option shows the arp-scan option to modify  this  field,  and  Notes
       gives the default value and any other notes.

       ┌───────────────────────────────────────────────────────────────┐
       │                 Outgoing ARP Packet Options                   │
       ├───────┬──────┬──────────┬─────────────────────────────────────┤
       │FieldBitsOptionNotes                               │
       ├───────┼──────┼──────────┼─────────────────────────────────────┤
       │ar$hrd │ 16   │ --arphrd │ Default is 1 (ARPHRD_ETHER)         │
       │ar$pro │ 16   │ --arppro │ Default is 0x0800                   │
       │ar$hln │ 8    │ --arphln │ Default is 6 (ETH_ALEN)             │
       │ar$pln │ 8    │ --arppln │ Default is 4 (IPv4)                 │
       │ar$op  │ 16   │ --arpop  │ Default is 1 (ARPOP_REQUEST)        │
       │ar$sha │ 48   │ --arpsha │ Default is interface h/w address    │
       │ar$spa │ 32   │ --arpspa │ Default is interface IP address     │
       │ar$tha │ 48   │ --arptha │ Default is zero (00:00:00:00:00:00) │
       │ar$tpa │ 32   │ None     │ Set to the target host IP address   │
       └───────┴──────┴──────────┴─────────────────────────────────────┘
       The  most  commonly  used outgoing ARP packet option is --arpspa, which sets the source IP
       address in the ARP packet.  This option allows the outgoing ARP packet to use a  different
       source IP address from the outgoing interface address.  With this option it is possible to
       use arp-scan on an interface with no IP address configured, which can  be  useful  if  you
       want to ensure that the testing host does not interact with the network being tested.

       Warning:  Setting ar$spa to the destination IP address can disrupt some operating systems,
       as they assume there is an IP address clash if they receive an ARP request for  their  own
       address.

       It  is  also  possible to change the values in the Ethernet frame header that precedes the
       ARP packet in the outgoing packets. The table below summarises  the  options  that  change
       values in the Ethernet frame header.

       ┌───────────────────────────────────────────────────────────────────┐
       │                 Outgoing Ethernet Frame Options                   │
       ├───────────────┬──────┬─────────────┬──────────────────────────────┤
       │FieldBitsOptionNotes                        │
       ├───────────────┼──────┼─────────────┼──────────────────────────────┤
       │Dest Address   │ 48   │ --destaddr  │ Default is ff:ff:ff:ff:ff:ff │
       │Source Address │ 48   │ --srcaddr   │ Default is interface address │
       │Protocol Type  │ 16   │ --prototype │ Default is 0x0806            │
       └───────────────┴──────┴─────────────┴──────────────────────────────┘
       The  most  commonly  used  outgoing  Ethernet  frame  option is --destaddr, which sets the
       destination Ethernet address for the ARP packet.  --prototype is not often  used,  because
       it will cause the packet to be interpreted as a different Ethernet protocol.

       Any ARP responses that are received are displayed in the following format:

       <IP Address>   <Hardware Address>   <Vendor Details>

       Where  IP  Address  is  the  IP  address of the responding target, Hardware Address is its
       Ethernet hardware address (also known as the MAC  address)  and  Vendor  Details  are  the
       vendor  details,  decoded from the hardware address.  The output fields are separated by a
       single tab character.

       The responses are displayed in the order they are received, which is not always  the  same
       order as the requests were sent because some hosts may respond faster than others.

       The  vendor  decoding  uses the files ieee-oui.txt, ieee-iab.txt and mac-vendor.txt, which
       are supplied with arp-scan.  The ieee-oui.txt and ieee-iab.txt files  are  generated  from
       the  OUI  and  IAB data on the IEEE website at http://standards.ieee.org/regauth/oui/ieee-
       oui.txt and http://standards.ieee.org/regauth/oui/iab.txt.  The Perl scripts  get-oui  and
       get-iab,  which  are  included  in the arp-scan package, can be used to update these files
       with the latest data from the IEEE website.  The mac-vendor.txt file contains other MAC to
       Vendor mappings that are not covered by the IEEE OUI and IAB files, and can be used to add
       custom mappings.

       Almost all hosts that support IP will respond to arp-scan if they receive  an  ARP  packet
       with  the  target  protocol  address  (ar$tpa)  set  to  their  IP address.  This includes
       firewalls and other hosts with IP filtering that drop all  IP  traffic  from  the  testing
       system.  For this reason, arp-scan is a useful tool to quickly determine all the active IP
       hosts on a given Ethernet network segment.

OPTIONS

       Where an option takes a value, that value is specified as a letter in angle brackets.  The
       letter indicates the type of data that is expected:

       <s>    A character string, e.g. --file=hostlist.txt.

       <i>    An  integer,  which can be specified as a decimal number or as a hexadecimal number
              if preceded with 0x, e.g. --arppro=2048 or --arpro=0x0800.

       <f>    A floating point decimal number, e.g. --backoff=1.5.

       <m>    An  Ethernet  MAC  address,  which  can  be  specified   either   in   the   format
              01:23:45:67:89:ab,  or  as  01-23-45-67-89-ab. The alphabetic hex characters may be
              either upper or lower case. E.g. --arpsha=01:23:45:67:89:ab.

       <a>    An IPv4 address, e.g. --arpspa=10.0.0.1

       <h>    Binary data specified as a hexadecimal string, which should not include  a  leading
              0x.  The  alphabetic  hex  characters  may  be  either  upper  or  lower case. E.g.
              --padding=aaaaaaaaaaaa

       <x>    Something else. See the description of the option for details.

       --help or -h
              Display this usage message and exit.

       --file=<s> or -f <s>
              Read hostnames or addresses from the specified file instead  of  from  the  command
              line. One name or IP address per line. Use "-" for standard input.

       --localnet or -l
              Generate addresses from network interface configuration.  Use the network interface
              IP address and network mask to generate the list of  target  host  addresses.   The
              list  will  include the network and broadcast addresses, so an interface address of
              10.0.0.1 with netmask 255.255.255.0 would generate 256 target hosts  from  10.0.0.0
              to  10.0.0.255  inclusive.   If  you use this option, you cannot specify the --file
              option  or  specify  any  target  hosts  on  the  command  line.    The   interface
              specifications  are  taken  from the interface that arp-scan will use, which can be
              changed with the --interface option.

       --retry=<i> or -r <i>
              Set total number of attempts per host to <i>, default=2.

       --timeout=<i> or -t <i>
              Set initial per host timeout to <i> ms, default=100.  This timeout is for the first
              packet sent to each host.  subsequent timeouts are multiplied by the backoff factor
              which is set with --backoff.

       --interval=<x> or -i <x>
              Set minimum packet interval to <x>.  This controls the outgoing bandwidth usage  by
              limiting  the  rate  at  which  packets can be sent. The packet interval will be no
              smaller than this number.  If you want to use up to a given bandwidth, then  it  is
              easier  to  use  the  --bandwidth  option  instead.   The  interval specified is in
              milliseconds by default, or in microseconds if "u" is appended to the value.

       --bandwidth=<x> or -B <x>
              Set desired outbound bandwidth to <x>, default=256000.  The value is  in  bits  per
              second  by default. If you append "K" to the value, then the units are kilobits per
              sec; and if you append "M" to the value, the units are megabits  per  second.   The
              "K" and "M" suffixes represent the decimal, not binary, multiples. So 64K is 64000,
              not 65536.  You cannot specify both --interval and  --bandwidth  because  they  are
              just different ways to change the same underlying parameter.

       --backoff=<f> or -b <f>
              Set  timeout  backoff  factor  to  <f>,  default=1.50.   The  per-host  timeout  is
              multiplied by this factor after each timeout. So, if the number of  retries  is  3,
              the initial per-host timeout is 500ms and the backoff factor is 1.5, then the first
              timeout will be 500ms, the second 750ms and the third 1125ms.

       --verbose or -v
              Display verbose progress messages.  Use more than once for greater effect:

              1 - Display the network address  and  mask  used  when  the  --localnet  option  is
              specified,  display  any  nonzero  packet  padding,  display  packets received from
              unknown hosts, and show when each pass through the list completes.

              2 - Show each packet sent and received, when entries are removed from the list, the
              pcap filter string, and counts of MAC/Vendor mapping entries.

              3 - Display the host list before scanning starts.

       --version or -V
              Display program version and exit.

       --random or -R
              Randomise the host list.  This option randomises the order of the hosts in the host
              list, so the ARP packets are sent to the hosts in a random order. It uses the Knuth
              shuffle algorithm.

       --numeric or -N
              IP  addresses only, no hostnames.  With this option, all hosts must be specified as
              IP addresses. Hostnames are not permitted. No DNS lookups will be performed.

       --snap=<i> or -n <i>
              Set the pcap snap length to <i>. Default=64.   This  specifies  the  frame  capture
              length.  This  length  includes  the  data-link  header.   The  default is normally
              sufficient.

       --interface=<s> or -I <s>
              Use network interface <s>.  If this option is not specified, arp-scan  will  search
              the  system  interface  list  for  the  lowest  numbered,  configured  up interface
              (excluding loopback).  The interface specified must support ARP.

       --quiet or -q
              Only display minimal output.  If this option is specified, then  only  the  minimum
              information is displayed. With this option, the OUI files are not used.

       --ignoredups or -g
              Don't  display  duplicate packets.  By default, duplicate packets are displayed and
              are flagged with "(DUP: n)".

       --ouifile=<s> or -O <s>
              Use OUI file <s>, default=/usr/local/share/arp-scan/ieee-oui.txt This file provides
              the IEEE Ethernet OUI to vendor string mapping.

       --iabfile=<s> or -F <s>
              Use IAB file <s>, default=/usr/local/share/arp-scan/ieee-iab.txt This file provides
              the IEEE Ethernet IAB to vendor string mapping.

       --macfile=<s> or -m <s>
              Use MAC/Vendor file <s>, default=/usr/local/share/arp-scan/mac-vendor.txt This file
              provides the custom Ethernet MAC to vendor string mapping.

       --srcaddr=<m> or -S <m>
              Set  the source Ethernet MAC address to <m>.  This sets the 48-bit hardware address
              in the Ethernet frame header for outgoing ARP  packets.  It  does  not  change  the
              hardware  address in the ARP packet, see --arpsha for details on how to change that
              address.  The default is the Ethernet address of the outgoing interface.

       --destaddr=<m> or -T <m>
              Send the packets to Ethernet MAC address  <m>  This  sets  the  48-bit  destination
              address  in  the  Ethernet  frame  header.   The  default  is the broadcast address
              ff:ff:ff:ff:ff:ff.  Most operating systems will also respond if the ARP request  is
              sent to their MAC address, or to a multicast address that they are listening on.

       --arpsha=<m> or -u <m>
              Use <m> as the ARP source Ethernet address This sets the 48-bit ar$sha field in the
              ARP packet It does not change  the  hardware  address  in  the  frame  header,  see
              --srcaddr  for  details  on how to change that address. The default is the Ethernet
              address of the outgoing interface.

       --arptha=<m> or -w <m>
              Use <m> as the ARP target Ethernet address This sets the 48-bit ar$tha field in the
              ARP  packet  The  default  is  zero, because this field is not used for ARP request
              packets.

       --prototype=<i> or -y <i>
              Set the Ethernet protocol type  to  <i>,  default=0x0806.   This  sets  the  16-bit
              protocol  type  field  in the Ethernet frame header.  Setting this to a non-default
              value will result in the packet being ignored by the target, or sent to  the  wrong
              protocol stack.

       --arphrd=<i> or -H <i>
              Use <i> for the ARP hardware type, default=1.  This sets the 16-bit ar$hrd field in
              the ARP packet.  The normal value is 1 (ARPHRD_ETHER). Most, but not all, operating
              systems  will  also  respond  to  6  (ARPHRD_IEEE802). A few systems respond to any
              value.

       --arppro=<i> or -p <i>
              Use <i> for the ARP protocol type, default=0x0800.  This  sets  the  16-bit  ar$pro
              field  in the ARP packet.  Most operating systems only respond to 0x0800 (IPv4) but
              some will respond to other values as well.

       --arphln=<i> or -a <i>
              Set the hardware address length to <i>, default=6.   This  sets  the  8-bit  ar$hln
              field in the ARP packet.  It sets the claimed length of the hardware address in the
              ARP packet. Setting it to any value other than the default will make the packet non
              RFC  compliant.   Some operating systems may still respond to it though.  Note that
              the actual lengths of the ar$sha and ar$tha  fields  in  the  ARP  packet  are  not
              changed by this option; it only changes the ar$hln field.

       --arppln=<i> or -P <i>
              Set  the  protocol  address  length  to <i>, default=4.  This sets the 8-bit ar$pln
              field in the ARP packet.  It sets the claimed length of the protocol address in the
              ARP packet. Setting it to any value other than the default will make the packet non
              RFC compliant.  Some operating systems may still respond to it though.   Note  that
              the  actual  lengths  of  the  ar$spa  and  ar$tpa fields in the ARP packet are not
              changed by this option; it only changes the ar$pln field.

       --arpop=<i> or -o <i>
              Use <i> for the ARP operation, default=1.  This sets the 16-bit ar$op field in  the
              ARP   packet.    Most   operating   systems  will  only  respond  to  the  value  1
              (ARPOP_REQUEST). However, some systems will respond to other values as well.

       --arpspa=<a> or -s <a>
              Use <a> as the source IP address.  The address should be specified in  dotted  quad
              format;  or the literal string "dest", which sets the source address to be the same
              as the target host address.  This sets the 32-bit ar$spa field in the  ARP  packet.
              Some  operating  systems check this, and will only respond if the source address is
              within the network of the receiving interface. Others don't care, and will  respond
              to any source address.  By default, the outgoing interface address is used.

              WARNING:  Setting  ar$spa  to the destination IP address can disrupt some operating
              systems, as they assume there is an IP address clash if they receive an ARP request
              for their own address.

       --padding=<h> or -A <h>
              Specify  padding  after  packet  data.  Set the padding data to hex value <h>. This
              data is appended to the end of the ARP packet, after the data.  Most, if  not  all,
              operating  systems will ignore any padding. The default is no padding, although the
              Ethernet driver on the sending system may pad the packet to  the  minimum  Ethernet
              frame length.

       --llc or -L
              Use RFC 1042 LLC framing with SNAP.  This option causes the outgoing ARP packets to
              use IEEE 802.2 framing with a SNAP header as described in RFC 1042. The default  is
              to  use Ethernet-II framing.  arp-scan will decode and display received ARP packets
              in either Ethernet-II or IEEE 802.2 formats irrespective of this option.

       --vlan=<i> or -Q <i>
              Use 802.1Q tagging with VLAN id <i>.  This option causes the outgoing  ARP  packets
              to use 802.1Q VLAN tagging with a VLAN ID of <i>, which should be in the range 0 to
              4095 inclusive.  arp-scan will always decode and display received  ARP  packets  in
              802.1Q format irrespective of this option.

       --pcapsavefile=<s> or -W <s>
              Write  received  packets  to  pcap  savefile  <s>.  This option causes received ARP
              responses to be written to the specified pcap savefile as well as being decoded and
              displayed.  This  savefile  can  be analysed with programs that understand the pcap
              file format, such as "tcpdump" and "wireshark".

FILES

       /usr/local/share/arp-scan/ieee-oui.txt
              List of IEEE OUI (Organisationally Unique Identifier) to vendor mappings.

       /usr/local/share/arp-scan/ieee-iab.txt
              List of IEEE IAB (Individual Address Block) to vendor mappings.

       /usr/local/share/arp-scan/mac-vendor.txt
              List of other Ethernet MAC to vendor mappings.

EXAMPLES

       The example below shows arp-scan being used to scan the network 192.168.0.0/24  using  the
       network interface eth0.

       $ arp-scan --interface=eth0 192.168.0.0/24
       Interface: eth0, datalink type: EN10MB (Ethernet)
       Starting arp-scan 1.4 with 256 hosts (http://www.nta-monitor.com/tools/arp-scan/)
       192.168.0.1     00:c0:9f:09:b8:db       QUANTA COMPUTER, INC.
       192.168.0.3     00:02:b3:bb:66:98       Intel Corporation
       192.168.0.5     00:02:a5:90:c3:e6       Compaq Computer Corporation
       192.168.0.6     00:c0:9f:0b:91:d1       QUANTA COMPUTER, INC.
       192.168.0.12    00:02:b3:46:0d:4c       Intel Corporation
       192.168.0.13    00:02:a5:de:c2:17       Compaq Computer Corporation
       192.168.0.87    00:0b:db:b2:fa:60       Dell ESG PCBA Test
       192.168.0.90    00:02:b3:06:d7:9b       Intel Corporation
       192.168.0.105   00:13:72:09:ad:76       Dell Inc.
       192.168.0.153   00:10:db:26:4d:52       Juniper Networks, Inc.
       192.168.0.191   00:01:e6:57:8b:68       Hewlett-Packard Company
       192.168.0.251   00:04:27:6a:5d:a1       Cisco Systems, Inc.
       192.168.0.196   00:30:c1:5e:58:7d       HEWLETT-PACKARD

       13 packets received by filter, 0 packets dropped by kernel
       Ending arp-scan: 256 hosts scanned in 3.386 seconds (75.61 hosts/sec).  13 responded

       This  next  example  shows arp-scan being used to scan the local network after configuring
       the network interface with DHCP using pump.

       # pump
       # ifconfig eth0
       eth0      Link encap:Ethernet  HWaddr 00:D0:B7:0B:DD:C7
                 inet addr:10.0.84.178  Bcast:10.0.84.183  Mask:255.255.255.248
                 UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
                 RX packets:46335 errors:0 dropped:0 overruns:0 frame:0
                 TX packets:1542776 errors:0 dropped:0 overruns:0 carrier:0
                 collisions:1644 txqueuelen:1000
                 RX bytes:6184146 (5.8 MiB)  TX bytes:348887835 (332.7 MiB)
       # arp-scan --localnet
       Interface: eth0, datalink type: EN10MB (Ethernet)
       Starting arp-scan 1.4 with 8 hosts (http://www.nta-monitor.com/tools/arp-scan/)
       10.0.84.179     00:02:b3:63:c7:57       Intel Corporation
       10.0.84.177     00:d0:41:08:be:e8       AMIGO TECHNOLOGY CO., LTD.
       10.0.84.180     00:02:b3:bd:82:9b       Intel Corporation
       10.0.84.181     00:02:b3:1f:73:da       Intel Corporation

       4 packets received by filter, 0 packets dropped by kernel
       Ending arp-scan 1.4: 8 hosts scanned in 0.820 seconds (9.76 hosts/sec).  4 responded

AUTHOR

       Roy Hills <Roy.Hills@nta-monitor.com>

SEE ALSO

       get-oui(1)

       get-iab(1)

       arp-fingerprint(1)

       RFC 826 - An Ethernet Address Resolution Protocol

       http://www.nta-monitor.com/wiki/ The arp-scan wiki page.

       http://www.nta-monitor.com/tools/arp-scan/ The arp-scan homepage.

                                         January 31, 2011                             ARP-SCAN(1)