2PING(8)																  2PING(8)

NAME

       2ping - A bi-directional ping client/listener

SYNOPSIS

       2ping [ options ] --listen | host/IP

DESCRIPTION

       2ping is a bi-directional ping utility.	It uses 3-way pings (akin to TCP SYN, SYN/ACK, ACK) and after-the-fact state comparison between a
       2ping listener and a 2ping client to determine which direction packet loss occurs.

       To use 2ping, start a listener on a known stable network host.  The relative network stability of the 2ping listener host should not be in
       question, because while 2ping can determine whether packet loss is occurring inbound or outbound relative to an endpoint, that will not
       help you determine the cause if both of the endpoints are in question.

       Once the listener is started, start 2ping in client mode and tell it to connect to the listener.  The ends will begin pinging each other
       and displaying network statistics.  If packet loss occurs, 2ping will wait a few seconds (default 10, configurable with -w) before
       comparing notes between the two endpoints to determine which direction the packet loss is occurring.

       To quit 2ping on the client or listener ends, enter ^C, and a list of statistics will be displayed.  To get a short inline display of
       statistics without quitting, send the process a QUIT signal (yes, that's the opposite of what you would think, but it's in line with the
       normal ping utility).

OPTIONS

       ping-compatible options:

       -a  Audible ping.

       -A  Adaptive ping.  A new client ping request is sent as soon as a client ping response is received.  If a ping response is not received
	   within the interval period, a new ping request is sent.  Minimal interval is 200msec for not super-user.  On networks with low rtt this
	   mode is essentially equivalent to flood mode.

	   2ping-specific notes: This behavior is somewhat different to the nature of ping's adaptive ping, but the result is roughly the same.

       -c count
	   Stop after sending count ping requests.

	   2ping-specific notes: This option behaves slightly differently from ping.  If both -c and -w are specified, satisfaction of -c will
	   cause an exit first.  Also, internally, 2ping exits just before sending count+1 pings, to give time for the ping to complete.

       -f  Flood ping. For every ping sent a period "." is printed, while for ever ping received a backspace is printed. This provides a rapid
	   display of how many pings are being dropped.  If interval is not given, it sets interval to zero and outputs pings as fast as they come
	   back or one hundred times per second, whichever is more.  Only the super-user may use this option with zero interval.

	   2ping-specific notes: Detected outbound/inbound loss responses are printed as ">" and "<", respectively.  Receive errors are printed as
	   "E".  Due to the asynchronous nature of 2ping, successful responses (backspaces) may overwrite these loss and error characters.

       -i interval
	   Wait interval seconds between sending each ping.  The default is to wait for one second between each ping normally, or not to wait in
	   flood mode.	Only super-user may set interval to values less 0.2 seconds.

       -I interface IP
	   Set source IP address.  When pinging IPv6 link-local address this option is required.  When in listener mode, this option may be
	   specified multiple to bind to multiple IP addresses.  When in client mode, this option may only be specified once, and all outbound
	   pings will be bound to this source IP.

	   2ping-specific notes: This option only takes an IP address, not a device name.  Note that in listener mode, if the machine has an
	   interface with multiple IP addresses and an request comes in via a sub IP, the reply still leaves via the interface's main IP.  So this
	   option must be used if you would like to respond via an interface's sub-IP.

       -l preload
	   If preload is specified, 2ping sends that many packets not waiting for reply.  Only the super-user may select preload more than 3.

       -p pattern
	   You may specify up to 16 "pad" bytes to fill out the packets you send.  This is useful for diagnosing data-dependent problems in a
	   network.  For example, -p ff will cause the sent packet pad area to be filled with all ones.

	   2ping-specific notes: This pads the portion of the packet that does not contain the active payload data.  If the active payload data is
	   larger than the minimum packet size (--min-packet-size=min), no padding will be sent.

       -q  Quiet output.  Nothing is displayed except the summary lines at startup time and when finished.

       -s packetsize
	   ping compatibility, this will set --min-packet-size to this plus 8 bytes.

       -v  Verbose output.  In 2ping, this prints decodes of packets that are sent and received.

       -V  Show version and exit.

       -w deadline
	   Specify a timeout, in seconds, before 2ping exits regardless of how many pings have been sent or received.  Due to blocking, this may
	   occur up to one second after the deadline specified.

	   2ping-specific notes: This option behaves slightly differently from ping.  If both -c and -w are specified, satisfaction of -c will
	   cause an exit first.

       2ping-specific options:

       -?, --help
	   Print a synposis and exit.

       -6, --ipv6
	   Bind/connect as IPv6.

       --auth=key
	   Set a shared key, send cryptographic hashes with each packet, and require cryptographic hashes from peer packets signed with the same
	   shared key.

       --auth-digest=digest
	   When --auth is used, specify the digest type to compute the cryptographic hash.  Valid options are hmac-md5 (default), hmac-sha1 and
	   hmac-sha256.  hmac-md5 requires Digest::MD5, and the SHA digests require Digest::SHA.

       --debug
	   Print (lots of) debugging information.

       --inquire-wait=secs
	   Wait at least secs seconds before inquiring about a lost packet.  Default is 10 seconds.  UDP packets can arrive delayed or out of
	   order, so it is best to give it some time before inquiring about a lost packet.

       --listen
	   Start as a listener.  The listener will not send out ping requests at regular intervals, and will instead wait for the far end to
	   initiate ping requests.  A listener is required as the remote end for a client.

       --min-packet-size=min
	   Set the minimum total payload size to min bytes, default 128.  If the payload is smaller than min bytes, padding will be added to the
	   end of the packet.

       --max-packet-size=max
	   Set the maximum total payload size to max bytes, default 512, absolute minimum 64.  If the payload is larger than max bytes,
	   information will be rearranged and sent in future packets when possible.

       --no-3way
	   Do not perform 3-way pings.	Used most often when combined with --listen, as the listener is usually the one to determine whether a
	   ping reply should become a 3-way ping.

	   Strictly speaking, a 3-way ping is not necessary for determining directional packet loss between the client and the listener.  However,
	   the extra leg of the 3-way ping allows for extra chances to determine packet loss more efficiently.	Also, with 3-way ping disabled,
	   the listener will receive no client performance indicators, nor will the listener be able to determine directional packet loss that it
	   detects.

       --no-match-packet-size
	   When sending replies, 2ping will try to match the packet size of the received packet by adding padding if necessary, but will not
	   exceed --max-packet-size.  --no-match-packet-size disabled this behavior, always setting the minimum to --min-packet-size.

       --no-send-version
	   Do not send the current running version of 2ping with each packet.

       --notice=text
	   Arbitrary notice text to send with each packet.  If the remote peer supports it, this may be displayed to the user.

       --packet-loss=out:in
	   Simulate random packet loss outbound and inbound.  For example, 25:10 means a 25% chance of not sending a packet, and a 10% chance of
	   ignoring a received packet.	A single number without colon separation means use the same percentage for both outbound and inbound.

       --port=port
	   Use UDP port port.  With --listen, this is the port to bind as, otherwise this is the port to send to.  Default is UDP port 15998.

       --stats=interval
	   Print a line of brief current statistics every interval seconds.  The same line can be printed on demand by sending SIGQUIT to the
	   2ping process.

BUGS

       There are probably lots and lots and lots of unknown bugs.

       By default, source IP logic doesn't work as expected, see -I for details.  There appears to be no way to peg the source IP of reply UDP
       packets to the destination of the packet that is being replied to.  As a result, packets always go out the interface's main IP address if
       not specified manually.	(Please, prove the author wrong.)

       This manpage isn't finished yet, and may never be.

AUTHOR

       2ping was written by Ryan Finnie <ryan@finnie.org>.

								    2012-04-22								  2PING(8)