ping(1M)
ping - send ICMP ECHO_REQUEST packets to network hosts
As shipped in IRIX 6.5.19. Last changed in IRIX 6.5.19.
NAME ping - send ICMP ECHO_REQUEST packets to network hosts SYNOPSIS /usr/etc/ping [ -4|-6] [-dDfLnoPqQrRv] [-c count] [-s size] [-i interval] [-l preload] [-p pattern] [-T ttl] [-t tos] [-w maxwait] [-I ifaddr] [-g gateway] [-h host] host DESCRIPTION Ping is a tool for network testing, measurement and management. It utilizes the ICMP protocol's ECHO_REQUEST datagram to elicit an ICMP ECHO_RESPONSE from a host or gateway. ECHO_REQUEST datagrams (``pings'') have an IP and ICMP header, followed by an 8-byte timestamp, and then an arbitrary number of ``pad'' bytes used to fill out the packet. The host can be the name of a host or its Internet address. The options are: -4 Choose the address family as AF_INET for resolving address of destination host. Address family determines which protocol to use. For this option, ping will use an IPv4 address associated with the hostname. If none exists, ping will state that the host is unknown and exit. It will not try to determine if an IPv6 address exists in the name service database. -6 Choose the address family as AF_INET6 for resolving address of destination host. For this option, ping will use an IPv6 address that is associated with the hostname. If none exists, ping will state that the host is unknown and exit. It will not try to determine if an IPv6 address exists in the name service database. If neither -4 nor -6 is provided, then if the name of a host is provided, not the literal IP address, and a valid IPv6 address exists in the name service database, ping will use this address. Otherwise, if the name service database contains an IPv4 address, it will try the IPv4 address. To override this default behavior, either -4 or -6 (only one of them) has to be provided. If both are provided, the last option is accepted and the first one is ignored. -c count Stop after sending (and waiting the specified delay to receive) count ECHO_RESPONSE packets. -d Set the SO_DEBUG option on the socket being used. -D Set the Don't Fragment bit in the IP header. This can be used to determine the path MTU. -f Flood ping. Send ECHO_REQUEST packets as fast as they are answered with ECHO_RESPONSE packets or one hundred times per second, whichever is more. (The repetition rate can be adjusted with the -i option.) For every ECHO_REQUEST sent a period (.) is printed, while for every ECHO_REPLY received a backspace is printed. This provides a rapid display of how many packets are being dropped. This can be extremely stressful on a network and should be used with caution. -g gateway Use Loose Source Routing to send the ECHO_REQUEST packets via gateway. -h host is an alternate way of specifying the target host instead of as the last argument. -i interval Wait interval seconds between sending each packet. The default is to wait for one second between each packet, except when the -f option is used when the default is "0.01" second or 10 milliseconds. -I interface Send multicast datagrams via the network interface specified by the interface's hostname or IP address. Send non-multicast datagrams with the specified source address. -l count Preload the network by sending count packets as fast as possible before falling into the normal mode of behavior. -L When sending to a multicast destination address, don't loop the datagram back to ourselves. -n Numeric output only. No attempt will be made to look up symbolic names for host addresses. This is useful to avoid waiting to convert the addresses of distant hosts to names. -o Exit successfully after receiving one reply packet. -p pattern You may specify up to 16 ``pad'' bytes to fill out the packet you send. This is useful for diagnosing data-dependent problems in a network. For example, ``-p ff'' will cause the sent packet to be filled with all ones. -P Use a psuedo-random sequence for the data instead of the default, fixed sequence of incrementing 8-bit integers. This is useful to foil compression on PPP and other links. -q Quiet output. Nothing is displayed except the summary line on termination. -Q Do not display responses such as Network Unreachable ICMP messages concerning the ECHO_REQUESTs sent. -r Bypass the normal routing tables and send directly to a host on an attached network. If the host is not on a directly-attached network, an error is returned. This option can be used to ping a local host through an interface that has no route through it (e.g., after the interface was dropped by routed(1M)). -R Record Route. Includes the RECORD_ROUTE option in the ECHO_REQUEST packet and displays the route buffer on returned packets. Note that the IP header is only large enough for eight such routes, and only six when using the -g option. Many hosts ignore or discard this option. -s size Send datagrams containing size bytes of data. The default is 56, which translates into 64 ICMP data bytes when combined with the 8 bytes of ICMP header data. The maximum allowed value is 61396. -t tos Use the specified hexadecimal type of service. -T ttl Changes the default time-to-live. -v Verbosely list ICMP packets other than ECHO_RESPONSE that are received by the system. By default, only ICMP packets (including ECHO_RESPONSEs) concerning the ECHO_REQUEST packets sent by ping are listed. When verbosity is turned on, almost all ICMP packets are listed, including error messages concerning other network traffic. -w maxwait Specifies the number of seconds to wait for a response to a packet before transmitting the next one. The default is 10.0. Ping should be used primarily for manual fault isolation. Because of the load it can impose on the network, it is unwise to use ping during normal operations or from automated scripts. When using ping for fault isolation, it should first be run on the local host, to verify that the local network interface is up and running. Then, hosts and gateways further and further away should be ``pinged''. Ping repeated sends individual datagrams (by default one per second), and prints one line of output for every ECHO_RESPONSE returned. On a trusted system with IP Security Options enabled, if the network idiom is not MONO, ping also prints a second line containing the hexadecimal representation of the IP security option in the ECHO_RESPONSE. If the -c count option is given, only that number of requests is sent. If there is no response, then no output other than the final summary is produced Round-trip times and packet loss statistics are computed. If duplicate packets are received, they are not included in the packet loss calculation, although the round trip time of these packets is used in calculating the minimum/average/maximum round-trip time numbers. When the specified number of packets have been sent (and received) or if the program is terminated with an interrupt (SIGINT), a brief summary is displayed. When not using the -f (flood) option, the first interrupt, usually generated by control-C or DEL, causes ping to wait for its outstanding requests to return. It will wait no longer than the longest round trip time encountered by previous, successful pings. The second interrupt stops ping immediately. DETAILS An IP header without options is 20 bytes. An ICMP ECHO_REQUEST packet contains an additional 8 bytes worth of ICMP header followed by an arbitrary amount of data. When a packetsize is given, it indicates the size of this extra piece of data (the default is 56). Thus the amount of data received inside of an IP packet of type ICMP ECHO_REPLY will always be 8 bytes more than the requested data space (the ICMP header). If the data space is at least eight bytes large, ping uses the first eight bytes of this space to include a timestamp to compute round trip times. If less than eight bytes of pad are specified, no round trip times are given. DUPLICATE AND DAMAGED PACKETS Ping will report duplicate and damaged packets. Duplicate packets should never occur, and seem to be caused by inappropriate link-level retransmissions. Duplicates may occur in many situations and are rarely (if ever) a good sign, although the presence of low levels of duplicates may not always be cause for alarm. Damaged packets are obviously serious cause for alarm and often indicate broken hardware somewhere in the ping packet's path (in the network or in the hosts). TRYING DIFFERENT DATA PATTERNS The (inter)network layer should never treat packets differently depending on the data contained in the data portion. Unfortunately, data-dependent problems have been known to sneak into networks and remain undetected for long periods of time. In many cases the particular pattern that will have problems is something that doesn't have sufficient ``transitions'', such as all ones or all zeros, or a pattern right at the edge, such as almost all zeros. It isn't necessarily enough to specify a data pattern of all zeros (for example) on the command line because the pattern that is of interest is at the data link level, and the relationship between what you type and what the controllers transmit can be complicated. This means that if you have a data-dependent problem you will probably have to do a lot of testing to find it. If you are lucky, you may manage to find a file that either can't be sent across your network or that takes much longer to transfer than other similar length files. You can then examine this file for repeated patterns that you can test using the -p option of ping. TTL DETAILS The TTL value of an IP packet represents the maximum number of IP routers that the packet can go through before being thrown away. In current practice you can expect each router in the Internet to decrement the TTL field by exactly one. The maximum possible value of this field is 255, and most Unix systems set the TTL field of ICMP ECHO_REQUEST packets to 255. In normal operation ping prints the ttl value from the packet it receives. When a remote system receives a ping packet, it can do one of three things with the TTL field in its response: o Not change it; this is what Berkeley Unix systems did before the 4.3BSD-tahoe release. In this case the TTL value in the received packet will be 255 minus the number of routers in the round-trip path. o Set it to 255; this is what IRIX and current Berkeley Unix systems do. In this case the TTL value in the received packet will be 255 minus the number of routers in the path from the remote system to the pinging host. o Set it to some other value. Some machines use the same value for ICMP packets that they use for TCP packets, for example either 30 or 60. Others may use completely wild values. EXIT STATUS Ping returns 0 on success (the host is alive), and non-zero if the arguments are incorrect or the host is not responding. BUGS Many Hosts and Gateways ignore the RECORD_ROUTE option. The maximum IP header length is too small for options like RECORD_ROUTE to be completely useful. There's not much that can be done about this, however. On a trusted system with IP Security Options enabled the IP header will not be able to accommodate both the security option and the RECORD_ROUTE option. Other IP options may not be supported if the security option is significantly large and in these situations the use of these options will be refused. Flood pinging is not recommended in general, and flood pinging the broadcast address should only be done under very controlled conditions. The record-route option does not work with many hosts and routers. SEE ALSO netstat(1), ifconfig(1M), routed(1M)