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>.