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2PING(1) - Linux manual page online | User commands

A bi-directional ping utility.

2PING(1) 2ping 2PING(1)


2ping - A bi-directional ping utility


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


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 sta‐ bility of the 2ping listener host should not be in question, because while 2ping can de‐ termine 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 --in‐ quire-wait) 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, enter ^\ or send the process a QUIT signal.


ping-compatible options (long option names are 2ping-specific): --audible, -a Audible ping. --adaptive, -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. On networks with low rtt this mode is essentially equivalent to flood mode. --count=count, -c count Stop after sending count ping requests. --flood, -f Flood ping. For every ping sent a period "." is printed, while for ever ping re‐ ceived 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. 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 er‐ ror characters. --interval=interval, -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. --interface-address=address, -I address Set source IP address. When in listener mode, this option may be specified multi‐ ple 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 ad‐ dresses and an request comes in via a sub IP, the reply still leaves via the inter‐ face's main IP. So either this option or --all-interfaces must be used if you would like to respond via an interface's sub-IP. --preload=count, -l count If specified, 2ping sends that many packets not waiting for reply. --pattern=hex_bytes, -p hex_bytes 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, --pat‐ tern=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), no padding will be sent. --quiet, -q Quiet output. Nothing is displayed except the summary lines at startup time and when finished. --packetsize-compat=bytes, -s bytes ping compatibility; this will set --min-packet-size to this plus 8 bytes. --verbose, -v Verbose output. In 2ping, this prints decodes of packets that are sent and re‐ ceived. --version, -V Show version and exit. --deadline=seconds, -w seconds 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 options: --help, -h Print a synposis and exit. --ipv4, -4 Limit binds to IPv4. In client mode, this forces resolution of dual-homed host‐ names to the IPv4 address. (Without --ipv4 or --ipv6, the first result will be used as specified by your operating system, usually the AAAA address on IPv6-routable machines, or the A address on IPv4-only machines.) In listener mode, this filters out any non-IPv4 --interface-address binds, either through hostname resolution or explicit passing. --ipv6, -6 Limit binds to IPv6. In client mode, this forces resolution of dual-homed host‐ names to the IPv6 address. (Without -4 or -6, the first result will be used as specified by your operating system, usually the AAAA address on IPv6-routable ma‐ chines, or the A address on IPv4-only machines.) In listener mode, this filters out any non-IPv6 --interface-address binds, either through hostname resolution or ex‐ plicit passing. --all-interfaces In listener mode, listen on all possible interface addresses. If used, this will override any addresses given by --interface-address. This functionality requires the netifaces module to be installed. --auth=key Set a shared key, send cryptographic hashes with each packet, and require crypto‐ graphic 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, hmac-sha256 and hmac-sha512. --debug Print (lots of) debugging information. --encrypt=key Set a shared key, encrypt 2ping packets, and require encrypted packets from peers encrypted with the same shared key. Requires the PyCrypto module. --encrypt-method=method When --encrypt is used, specify the method used to encrypt packets. Valid options are hkdf-aes256-cbc (default). --fuzz=percent Simulate corruption of incoming packets, with a percent probability each bit will be flipped. After fuzzing, the packet checksum will be recalculated, and then the checksum itself will be fuzzed (but at a lower probability). --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 in‐ tervals, and will instead wait for the far end to initiate ping requests. A lis‐ tener 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. --nagios=wrta,wloss%,crta,closs% Produce output suitable for use in a Nagios check. If --count is not specified, defaults to 5 pings. A warning condition (exit code 1) will be returned if average RTT exceeds wrta or ping loss exceeds wloss%. A critical condition (exit code 2) will be returned if average RTT exceeds crta or ping loss exceeds closs%. --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 pack‐ et 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 Send arbitrary notice text 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 out‐ bound and inbound. --port=port Use UDP port port, either a numeric port number of a service name string. With --listen, this is the port to bind as, otherwise this is the port to send to. De‐ fault is UDP port 15998. --send-monotonic-clock Send a monotonic clock value with each packet. Peer time (if sent by the peer) can be viewed with --verbose. Only supported if the system is capable of generating a monotonic clock. --send-random=bytes Send random data to the peer, up to bytes. The number of bytes will be limited by other factors, up to --max-packet-size. If this data is to be used for trusted purposes, it should be combined with --auth for HMAC authentication. --send-time Send the host time (wall clock) with each packet. Peer time (if sent by the peer) can be viewed with --verbose. --srv In client mode, causes hostnames to be looked up via DNS SRV records. If the SRV query returns multiple record targets, they will all be pinged in parallel; priori‐ ty and weight are not considered. The record's port will be used instead of --port. This functionality requires the dnspython module to be installed. --stats=interval Print a line of brief current statistics every interval seconds. The same line can be printed on demand by entering ^\ or sending the QUIT signal to the 2ping process.


None known, many assumed.


2ping was written by Ryan Finnie <>.


Ryan Finnie.
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