Provided by: 2ping_2.0-1_all 
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)