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@ -10,36 +10,36 @@ fping \- send ICMP ECHO_REQUEST packets to network hosts
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.NXR "fping command"
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.NXR "ICMP ECHO_REQUEST"
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.B fping
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.B fping
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is a program like
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.B ping(8)
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which uses the Internet Control
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Message Protocol (ICMP) echo request to determine if a target host is
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responding.
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.B fping
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responding.
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.B fping
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differs from ping in that you can specify any
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number of targets on the command line, or specify a file containing
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the lists of targets to ping. Instead of sending to one target until it
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times out or replies,
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.B fping
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times out or replies,
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.B fping
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will send out a ping packet and move
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on to the next target in a round-robin fashion.
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on to the next target in a round-robin fashion.
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.PP
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In the default mode, if a target replies,
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it is noted and removed from the list of targets to check; if a target
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does not respond within a certain time limit and/or retry limit it
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is designated as unreachable.
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.B fping
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does not respond within a certain time limit and/or retry limit it
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is designated as unreachable.
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.B fping
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also supports sending a specified number of pings to a target, or
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looping indefinitely (as in
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looping indefinitely (as in
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.B ping
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).
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.PP
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Unlike
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Unlike
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.B ping,
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.B fping
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is meant to be used in scripts, so its output is designed to be
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.B fping
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is meant to be used in scripts, so its output is designed to be
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easy to parse.
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.SH OPTIONS
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.IP \fB\-a\fR 5
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@ -48,12 +48,12 @@ Show systems that are alive.
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Display targets by address rather than DNS name.
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.IP \fB\-b\fIn\fR 5
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Number of bytes of ping data to send. The minimum size (normally 12)
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allows room for the data that
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.B fping
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allows room for the data that
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.B fping
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needs to do its work (sequence number, timestamp). The reported
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received data size includes the IP header (normally 20 bytes) and ICMP
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header (8 bytes), so the minimum total size is 40 bytes. Default is
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56, as in
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56, as in
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.B ping.
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Maximum is the theoretical maximum IP datagram size (64K), though most
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systems limit this to a smaller, system-dependent number.
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@ -135,7 +135,7 @@ Set source address.
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Set the interface (requires SO_BINDTODEVICE support)
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.IP \fB\-t\fIn\fR 5
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Initial target timeout in milliseconds (default 500). In the default
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mode, this is the amount of time that
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mode, this is the amount of time that
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.B fping
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waits for a response to its first request. Successive timeouts are
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multiplied by the backoff factor.
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@ -146,7 +146,7 @@ Show targets that are unreachable.
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.IP \fB\-T\fIn\fR 5
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Set the typ of service flag (TOS). \fIn\fR can be either decimal or hexadecimal (0xh) format.
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.IP \fB\-v\fR 5
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Print
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Print
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.B fping
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version information.
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@ -154,9 +154,9 @@ version information.
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The following perl script will check a list of hosts and send mail if
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any are unreachable. It uses the open2 function which allows a program
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to be opened for reading and writing. fping does not start pinging the
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list of systems until it reads EOF, which it gets after INPUT is closed.
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list of systems until it reads EOF, which it gets after INPUT is closed.
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Sure the open2 usage is not needed in this example, but it's a good open2
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example none the less.
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example none the less.
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.nf
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#!/usr/bin/perl
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@ -210,11 +210,11 @@ command line arguments, and 4 for a system call failure.
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.SH BUGS
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Ha! If we knew of any we would have fixed them!
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.SH RESTRICTIONS
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If certain options are used (i.e, a low value for \-i and \-t, and a
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If certain options are used (i.e, a low value for \-i and \-t, and a
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high value for \-r) it is possible to flood the network. This program
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must be installed as setuid root in order to open up a raw socket,
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or must be run by root. In order to stop mere mortals from hosing the
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network (when fping is installed setuid root) , normal users can't specify
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network (when fping is installed setuid root) , normal users can't specify
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the following:
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.nf
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