ping - send ICMP ECHO_REQUEST to network hosts
] [-c count
] [-i interval
] [-l preload
] [-M pmtudisc_option
] [-w deadline
] [-p pattern
] [-s packetsize
] [-t ttl
] [hop ...
uses the ICMP protocol's mandatory 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 a struct timeval and then
an arbitrary number of ``pad'' bytes used to fill out the packet.
works with both IPv4 and IPv6. Using only one of them explicitly can
be enforced by specifying -4
can also send IPv6 Node Information Queries (RFC4620). Intermediate
s may not be allowed, because IPv6 source routing was deprecated
- Use IPv4 only.
- Use IPv6 only.
- Audible ping.
- Adaptive ping. Interpacket interval adapts to round-trip
time, so that effectively not more than one (or more, if preload is set)
unanswered probe is present in the network. Minimal interval is 200msec
for not super-user. On networks with low rtt this mode is essentially
equivalent to flood mode.
- Allow pinging a broadcast address.
- Do not allow ping to change source address of
probes. The address is bound to one selected when ping starts.
- -c count
- Stop after sending count ECHO_REQUEST packets. With
deadline option, ping waits for count ECHO_REPLY
packets, until the timeout expires.
- Set the SO_DEBUG option on the socket being used.
Essentially, this socket option is not used by Linux kernel.
- Print timestamp (unix time + microseconds as in
gettimeofday) before each line.
- Flood ping. For every ECHO_REQUEST sent a period ``.'' is
printed, while for ever ECHO_REPLY received a backspace is printed. This
provides a rapid display of how many packets are being dropped. If
interval is not given, it sets interval to zero and outputs packets 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.
- -F flow label
- IPv6 only. Allocate and set 20 bit flow label (in hex) on
echo request packets. If value is zero, kernel allocates random flow
- Show help.
- -i interval
- Wait interval seconds between sending each packet.
The default is to wait for one second between each packet normally, or not
to wait in flood mode. Only super-user may set interval to values less
than 0.2 seconds.
- -I interface
- interface is either an address, or an interface
name. If interface is an address, it sets source address to
specified interface address. If interface in an interface name, it
sets source interface to specified interface. For IPv6, when doing ping to
a link-local scope address, link specification (by the '%'-notation in
destination, or by this option) is required.
- -l preload
- If preload is specified, ping sends that many
packets not waiting for reply. Only the super-user may select preload more
- Suppress loopback of multicast packets. This flag only
applies if the ping destination is a multicast address.
- -m mark
- use mark to tag the packets going out. This is
useful for variety of reasons within the kernel such as using policy
routing to select specific outbound processing.
- -M pmtudisc_opt
- Select Path MTU Discovery strategy. pmtudisc_option
may be either do (prohibit fragmentation, even local one),
want (do PMTU discovery, fragment locally when packet size is
large), or dont (do not set DF flag).
- -N nodeinfo_option
- IPv6 only. Send ICMPv6 Node Information Queries (RFC4620),
instead of Echo Request. CAP_NET_RAW capability is required.
- Show help for NI support.
- Queries for Node Names.
- Queries for IPv6 Addresses. There are several IPv6 specific
- Request IPv6 global-scope addresses.
- Request IPv6 site-local addresses.
- Request IPv6 link-local addresses.
- Request IPv6 addresses on other interfaces.
- Queries for IPv4 Addresses. There is one IPv4 specific
- Request IPv4 addresses on other interfaces.
- IPv6 subject address.
- IPv4 subject address.
- Subject name. If it contains more than one dot,
fully-qualified domain name is assumed.
- Subject name. Fully-qualified domain name is always
- Numeric output only. No attempt will be made to lookup
symbolic names for host addresses.
- Report outstanding ICMP ECHO reply before sending next
packet. This is useful together with the timestamp -D to log output
to a diagnostic file and search for missing answers.
- -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.
- Quiet output. Nothing is displayed except the summary lines
at startup time and when finished.
- -Q tos
- Set Quality of Service -related bits in ICMP datagrams.
tos can be decimal ( ping only) or hex number.
In RFC2474, these fields are interpreted as 8-bit Differentiated Services
(DS), consisting of: bits 0-1 (2 lowest bits) of separate data, and bits
2-7 (highest 6 bits) of Differentiated Services Codepoint (DSCP). In
RFC2481 and RFC3168, bits 0-1 are used for ECN.
Historically (RFC1349, obsoleted by RFC2474), these were interpreted as: bit
0 (lowest bit) for reserved (currently being redefined as congestion
control), 1-4 for Type of Service and bits 5-7 (highest bits) for
- Bypass the normal routing tables and send directly to a
host on an attached interface. 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 provided the option
-I is also used.
- ping only. 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 nine
such routes. Many hosts ignore or discard this option.
- -s packetsize
- Specifies the number of data bytes to be sent. The default
is 56, which translates into 64 ICMP data bytes when combined with the 8
bytes of ICMP header data.
- -S sndbuf
- Set socket sndbuf. If not specified, it is selected to
buffer not more than one packet.
- -t ttl
- ping only. Set the IP Time to Live.
- -T timestamp option
- Set special IP timestamp options. timestamp option
may be either tsonly (only timestamps), tsandaddr
(timestamps and addresses) or tsprespec host1 [host2 [host3
[host4]]] (timestamp prespecified hops).
- Print full user-to-user latency (the old behaviour).
Normally ping prints network round trip time, which can be
different f.e. due to DNS failures.
- Verbose output.
- Show version and exit.
- -w deadline
- Specify a timeout, in seconds, before ping exits
regardless of how many packets have been sent or received. In this case
ping does not stop after count packet are sent, it waits
either for deadline expire or until count probes are
answered or for some error notification from network.
- -W timeout
- Time to wait for a response, in seconds. The option affects
only timeout in absence of any responses, otherwise ping waits for
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''. 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 a
SIGINT, a brief summary is displayed. Shorter current statistics can be
obtained without termination of process with signal SIGQUIT.
does not receive any reply packets at all it will exit with code
1. If a packet count
are both specified, and fewer
packets are received by the time the deadline
arrived, it will also exit with code 1. On other error it exits with code 2.
Otherwise it exits with code 0. This makes it possible to use the exit code to
see if a host is alive or not.
This program is intended for use in network testing, measurement and management.
Because of the load it can impose on the network, it is unwise to use
during normal operations or from automated scripts.
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, this indicated 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 of size of struct timeval ping
beginning bytes of this space to include a timestamp which it uses in the
computation of round trip times. If the data space is shorter, no round trip
times are given.
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
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
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
The TCP/IP specification states that the TTL field for TCP packets should be set
to 60, but many systems use smaller values (4.3 BSD uses 30, 4.2 used 15).
The maximum possible value of this field is 255, and most Unix systems set the
TTL field of ICMP ECHO_REQUEST packets to 255. This is why you will find you
can ``ping'' some hosts, but not reach them with telnet(1)
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:
- 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
- Set it to 255; this is what 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.
- 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.
- Many Hosts and Gateways ignore the RECORD_ROUTE
- 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.
- Flood pinging is not recommended in general, and flood
pinging the broadcast address should only be done under very controlled
command appeared in 4.3BSD.
The version described here is its descendant specific to Linux.
As of version s20150815, the ping6
binary doesn't exist anymore. It has
been merged into ping
. Creating a symlink named ping6
will result in the same funcionality as before.
requires CAP_NET_RAW capability to be executed 1) if the program is
used for non-echo queries (See -N
option), or 2) if kernel does not
support non-raw ICMP sockets, or 3) if the user is not allowed to create an
ICMP echo socket. The program may be used as set-uid root.
is part of iputils
package and the latest versions are
available in source form at