fping - send ICMP ECHO_REQUEST packets to network hosts
] [ systems...
is a program like ping
which uses the Internet Control
Message Protocol (ICMP) echo request to determine if a target host is
differs from ping
in that you can specify any
number of targets on the command line, or specify a file containing the lists
of targets to ping. Instead of sending to one target until it times out or
will send out a ping packet and move on to the next
target in a round-robin fashion. In the default mode, if a target replies, it
is noted and removed from the list of targets to check; if a target does not
respond within a certain time limit and/or retry limit it is designated as
also supports sending a specified number of pings to
a target, or looping indefinitely (as in ping
). Unlike ping
is meant to be used in scripts, so its output is designed to be
easy to parse.
- -4, --ipv4
- Restrict name resolution and IPs to IPv4 addresses.
- -6, --ipv6
- Restrict name resolution and IPs to IPv6 addresses.
- -a, --alive
- Show systems that are alive.
- -A, --addr
- Display targets by address rather than DNS name. Combined
with -d, the output will be both the ip and (if available) the
- -b, --size=BYTES
- Number of bytes of ping data to send. The minimum size
(normally 12) allows room for the data that fping needs to do its
work (sequence number, timestamp). The reported received data size
includes the IP header (normally 20 bytes) and ICMP header (8 bytes), so
the minimum total size is 40 bytes. Default is 56, as in ping.
Maximum is the theoretical maximum IP datagram size (64K), though most
systems limit this to a smaller, system-dependent number.
- -B, --backoff=N
- Backoff factor. In the default mode, fping sends
several requests to a target before giving up, waiting longer for a reply
on each successive request. This parameter is the value by which the wait
time ( -t) is multiplied on each successive request; it must be
entered as a floating-point number (x.y). The default is 1.5.
- -c, --count=N
- Number of request packets to send to each target. In this
mode, a line is displayed for each received response (this can suppressed
with -q or -Q). Also, statistics about responses for each
target are displayed when all requests have been sent (or when
- -C, --vcount=N
- Similar to -c, but the per-target statistics are
displayed in a format designed for automated response-time statistics
gathering. For example:
$ fping -C 5 -q somehost
somehost : 91.7 37.0 29.2 - 36.8
shows the response time in milliseconds for each of the five requests, with
the "-" indicating that no response was received to the fourth
- -d, --rdns
- Use DNS to lookup address of return ping packet. This
allows you to give fping a list of IP addresses as input and print
hostnames in the output. This is similar to option
-n/--name, but will force a reverse-DNS lookup even if you
give hostnames as target (NAME->IP->NAME).
- -D, --timestamp
- Add Unix timestamps in front of output lines generated with
in looping or counting modes ( -l, -c, or -C).
- -e, --elapsed
- Show elapsed (round-trip) time of packets.
- -f, --file
- Read list of targets from a file. This option can only be
used by the root user. Regular users should pipe in the file via stdin:
$ fping < targets_file
- -g, --generate addr/mask
- Generate a target list from a supplied IP netmask, or a
starting and ending IP. Specify the netmask or start/end in the targets
portion of the command line. If a network with netmask is given, the
network and broadcast addresses will be excluded. ex. To ping the network
192.168.1.0/24, the specified command line could look like either:
$ fping -g 192.168.1.0/24
$ fping -g 192.168.1.1 192.168.1.254
- -h, --help
- Print usage message.
- -H, --ttl=N
- Set the IP TTL field (time to live hops).
- -i, --interval=MSEC
- The minimum amount of time (in milliseconds) between
sending a ping packet to any target (default is 10, minimum is 1).
- -I, --iface=IFACE
- Set the interface (requires SO_BINDTODEVICE support).
- -l, --loop
- Loop sending packets to each target indefinitely. Can be
interrupted with Ctrl-C; statistics about responses for each target are
- -m, --all
- Send pings to each of a target host's multiple IP addresses
(use of option '-A' is recommended).
- -M, --dontfrag
- Set the "Don't Fragment" bit in the IP header
(used to determine/test the MTU).
- -n, --name
- If targets are specified as IP addresses, do a reverse-DNS
lookup on them to
- -N, --netdata
- Format output for netdata (-l -Q are required). See:
- -o, --outage
- Calculate "outage time" based on the number of
lost pings and the interval used (useful for network convergence
- -O, --tos=N
- Set the typ of service flag (TOS). N can be either
decimal or hexadecimal (0xh) format.
- -p, --period=MSEC
- In looping or counting modes (-l, -c, or
-C), this parameter sets the time in milliseconds that fping
waits between successive packets to an individual target. Default is 1000
and minimum is 10.
- -q, --quet
- Quiet. Don't show per-probe results, but only the final
summary. Also don't show ICMP error messages.
- -Q, --squiet=SECS
- Like -q, but show summary results every n
- -r, --retry=N
- Retry limit (default 3). This is the number of times an
attempt at pinging a target will be made, not including the first
- -R, --random
- Instead of using all-zeros as the packet data, generate
random bytes. Use to defeat, e.g., link data compression.
- -s, --src
- Print cumulative statistics upon exit.
- -S, --src=addr
- Set source address.
- -t, --timeout=MSEC
- Initial target timeout in milliseconds. In the default,
non-loop mode, the default timeout is 500ms, and it represents the amount
of time that fping waits for a response to its first request.
Successive timeouts are multiplied by the backoff factor specified with
In loop/count mode, the default timeout is automatically adjusted to match
the "period" value (but not more than 2000ms). You can still
adjust the timeout value with this option, if you wish to, but note that
setting a value larger than "period" produces inconsistent
results, because the timeout value can be respected only for the last
Also note that any received replies that are larger than the timeout value,
will be discarded.
- -T n
- Ignored (for compatibility with fping 2.4).
- -u, --unreach
- Show targets that are unreachable.
- -v, --version
- Print fping version information.
Generate 20 pings to two hosts in ca. 1 second (i.e. one ping every 50 ms to
each host), and report every ping RTT at the end:
$ fping --quiet --interval=1 --vcount=20 --period=50 127.0.0.1 127.0.0.2
- Roland J. Schemers III, Stanford University, concept and
- RL "Bob" Morgan, Stanford University, versions
- David Papp, versions 2.3x and up
fping website: <http://www.fping.org>
- David Schweikert, versions 3.0 and up
Exit status is 0 if all the hosts are reachable, 1 if some hosts were
unreachable, 2 if any IP addresses were not found, 3 for invalid command line
arguments, and 4 for a system call failure.
If fping was configured with "--enable-safe-limits", the following
values are not allowed for non-root users:
- -i n, where n < 1 msec
- -p n, where n < 10 msec