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"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
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<refentry id='ping8'>
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<refmeta>
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<refentrytitle>PING</refentrytitle>
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<manvolnum>8</manvolnum>
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<refmiscinfo class='manual'>iputils</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>ping</refname>
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<refpurpose>send ICMP ECHO_REQUEST to network hosts</refpurpose>
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</refnamediv>
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<refsynopsisdiv id='synopsis'>
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<cmdsynopsis>
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<command>ping</command>
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<arg choice='opt'>-aAbBdDfhLnOqrRUvV46 </arg>
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<arg choice='opt'>-c <replaceable>count</replaceable></arg>
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<arg choice='opt'>-F <replaceable>flowlabel</replaceable></arg>
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<arg choice='opt'>-i <replaceable>interval</replaceable></arg>
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<arg choice='opt'>-I <replaceable>interface</replaceable></arg>
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<arg choice='opt'>-l <replaceable>preload</replaceable></arg>
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<arg choice='opt'>-m <replaceable>mark</replaceable></arg>
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<arg choice='opt'>-M <replaceable>pmtudisc_option</replaceable></arg>
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<arg choice='opt'>-N <replaceable>nodeinfo_option</replaceable></arg>
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<arg choice='opt'>-w <replaceable>deadline</replaceable></arg>
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<arg choice='opt'>-W <replaceable>timeout</replaceable></arg>
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<arg choice='opt'>-p <replaceable>pattern</replaceable></arg>
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<arg choice='opt'>-Q <replaceable>tos</replaceable></arg>
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<arg choice='opt'>-s <replaceable>packetsize</replaceable></arg>
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<arg choice='opt'>-S <replaceable>sndbuf</replaceable></arg>
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<arg choice='opt'>-t <replaceable>ttl</replaceable></arg>
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<arg choice='opt'><arg choice='plain'>-T <replaceable>timestamp</replaceable></arg><arg choice='plain'><replaceable>option</replaceable></arg></arg>
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<arg choice='opt' rep='repeat'><replaceable>hop</replaceable></arg>
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<arg choice='plain'><replaceable>destination</replaceable></arg>
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<sbr/>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1 id='description'>
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<title>DESCRIPTION</title>
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<para><command>ping</command> uses the ICMP protocol's mandatory ECHO_REQUEST
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datagram to elicit an ICMP ECHO_RESPONSE from a host or gateway.
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ECHO_REQUEST datagrams (“pings”) have an IP and ICMP
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header, followed by a struct timeval and then an arbitrary
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number of “pad” bytes used to fill out the packet.</para>
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<para><command>ping</command> works with both IPv4 and IPv6. Using only one of them
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explicitly can be enforced by specifying <option>-4</option> or <option>-6</option>.</para>
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<para><command>ping</command> can also send IPv6 Node Information Queries (RFC4620).
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Intermediate <emphasis remap='I'>hop</emphasis>s may not be allowed, because IPv6 source routing was deprecated (RFC5095).</para>
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</refsect1>
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<refsect1 id='options'>
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<title>OPTIONS</title>
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<variablelist remap='TP'>
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<varlistentry>
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<term><option>-4</option></term>
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<listitem>
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<para>Use IPv4 only.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-6</option></term>
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<listitem>
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<para>Use IPv6 only.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-a</option></term>
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<listitem>
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<para>Audible ping.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-A</option></term>
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<listitem>
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<para>Adaptive ping. Interpacket interval adapts to round-trip time, so that
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effectively not more than one (or more, if preload is set) unanswered probe
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is present in the network. Minimal interval is 200msec for not super-user.
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On networks with low rtt this mode is essentially equivalent to flood mode.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-b</option></term>
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<listitem>
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<para>Allow pinging a broadcast address.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-B</option></term>
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<listitem>
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<para>Do not allow <command>ping</command> to change source address of probes.
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The address is bound to one selected when <command>ping</command> starts.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-c </option><emphasis remap='I'>count</emphasis></term>
|
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<listitem>
|
|
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<para>Stop after sending <emphasis remap='I'>count</emphasis> ECHO_REQUEST
|
|
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packets. With <emphasis remap='I'>deadline</emphasis> option, <command>ping</command> waits for
|
|
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<emphasis remap='I'>count</emphasis> ECHO_REPLY packets, until the timeout expires.</para>
|
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-d</option></term>
|
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<listitem>
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<para>Set the SO_DEBUG option on the socket being used.
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Essentially, this socket option is not used by Linux kernel.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-D</option></term>
|
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<listitem>
|
|
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<para>Print timestamp (unix time + microseconds as in gettimeofday) before
|
|
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each line.</para>
|
|
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</listitem>
|
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</varlistentry>
|
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<varlistentry>
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<term><option>-f</option></term>
|
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<listitem>
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<para>Flood ping. For every ECHO_REQUEST sent a period “.” is printed,
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while for ever ECHO_REPLY received a backspace is printed.
|
|
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This provides a rapid display of how many packets are being dropped.
|
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If interval is not given, it sets interval to zero and
|
|
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outputs packets as fast as they come back or one hundred times per second,
|
|
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whichever is more.
|
|
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Only the super-user may use this option with zero interval.</para>
|
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</listitem>
|
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</varlistentry>
|
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<varlistentry>
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<term><option>-F </option><emphasis remap='I'>flow label</emphasis></term>
|
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<listitem>
|
|
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<para>IPv6 only.
|
|
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Allocate and set 20 bit flow label (in hex) on echo request packets.
|
|
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If value is zero, kernel allocates random flow label.</para>
|
|
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</listitem>
|
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</varlistentry>
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<varlistentry>
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<term><option>-h</option></term>
|
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<listitem>
|
|
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<para>Show help.</para>
|
|
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</listitem>
|
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</varlistentry>
|
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<varlistentry>
|
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<term><option>-i </option><emphasis remap='I'>interval</emphasis></term>
|
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<listitem>
|
|
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<para>Wait <emphasis remap='I'>interval</emphasis> seconds between sending each packet.
|
|
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The default is to wait for one second between each packet normally,
|
|
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or not to wait in flood mode. Only super-user may set interval
|
|
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to values less than 0.2 seconds.</para>
|
|
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</listitem>
|
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</varlistentry>
|
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<varlistentry>
|
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<term><option>-I </option><emphasis remap='I'>interface</emphasis></term>
|
|
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<listitem>
|
|
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<para><emphasis remap='I'>interface</emphasis> is either an address, or an interface name.
|
|
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If <emphasis remap='I'>interface</emphasis> is an address, it sets source address
|
|
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to specified interface address.
|
|
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If <emphasis remap='I'>interface</emphasis> in an interface name, it sets
|
|
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source interface to specified interface.
|
|
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NOTE: For IPv6, when doing ping to a link-local scope
|
|
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address, link specification (by the '%'-notation in
|
|
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<emphasis remap='I'>destination</emphasis>, or by this option)
|
|
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can be used but it is no longer required.</para>
|
|
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</listitem>
|
|
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</varlistentry>
|
|
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<varlistentry>
|
|
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<term><option>-l </option><emphasis remap='I'>preload</emphasis></term>
|
|
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<listitem>
|
|
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<para>If <emphasis remap='I'>preload</emphasis> is specified,
|
|
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<command>ping</command> sends that many packets not waiting for reply.
|
|
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Only the super-user may select preload more than 3.</para>
|
|
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</listitem>
|
|
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</varlistentry>
|
|
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<varlistentry>
|
|
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<term><option>-L</option></term>
|
|
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<listitem>
|
|
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<para>Suppress loopback of multicast packets. This flag only applies if the ping
|
|
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destination is a multicast address.</para>
|
|
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</listitem>
|
|
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</varlistentry>
|
|
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<varlistentry>
|
|
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<term><option>-m </option><emphasis remap='I'>mark</emphasis></term>
|
|
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<listitem>
|
|
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<para>use <emphasis remap='I'>mark</emphasis> to tag the packets going out. This is useful
|
|
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for variety of reasons within the kernel such as using policy
|
|
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routing to select specific outbound processing.</para>
|
|
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</listitem>
|
|
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</varlistentry>
|
|
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<varlistentry>
|
|
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<term><option>-M </option><emphasis remap='I'>pmtudisc_opt</emphasis></term>
|
|
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<listitem>
|
|
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<para>Select Path MTU Discovery strategy.
|
|
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<emphasis remap='I'>pmtudisc_option</emphasis> may be either <emphasis remap='I'>do</emphasis>
|
|
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(prohibit fragmentation, even local one),
|
|
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<emphasis remap='I'>want</emphasis> (do PMTU discovery, fragment locally when packet size
|
|
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is large), or <emphasis remap='I'>dont</emphasis> (do not set DF flag).</para>
|
|
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</listitem>
|
|
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</varlistentry>
|
|
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<varlistentry>
|
|
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<term><option>-N </option><emphasis remap='I'>nodeinfo_option</emphasis></term>
|
|
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<listitem>
|
|
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<para>IPv6 only.
|
|
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Send ICMPv6 Node Information Queries (RFC4620), instead of Echo Request.
|
|
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CAP_NET_RAW capability is required.</para>
|
|
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<variablelist remap='TP'>
|
|
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<varlistentry>
|
|
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<term><emphasis remap='B'>help</emphasis></term>
|
|
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<listitem>
|
|
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<para>Show help for NI support.</para>
|
|
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6f2e62 |
</listitem>
|
|
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6f2e62 |
</varlistentry>
|
|
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</variablelist>
|
|
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<variablelist remap='TP'>
|
|
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<varlistentry>
|
|
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<term><emphasis remap='B'>name</emphasis></term>
|
|
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6f2e62 |
<listitem>
|
|
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<para>Queries for Node Names.</para>
|
|
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6f2e62 |
</listitem>
|
|
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6f2e62 |
</varlistentry>
|
|
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6f2e62 |
</variablelist>
|
|
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6f2e62 |
<variablelist remap='TP'>
|
|
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<varlistentry>
|
|
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<term><emphasis remap='B'>ipv6</emphasis></term>
|
|
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6f2e62 |
<listitem>
|
|
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6f2e62 |
<para>Queries for IPv6 Addresses. There are several IPv6 specific flags.</para>
|
|
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6f2e62 |
<variablelist remap='TP'>
|
|
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6f2e62 |
<varlistentry>
|
|
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<term><emphasis remap='B'>ipv6-global</emphasis></term>
|
|
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6f2e62 |
<listitem>
|
|
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6f2e62 |
<para>Request IPv6 global-scope addresses.</para>
|
|
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6f2e62 |
</listitem>
|
|
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6f2e62 |
</varlistentry>
|
|
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6f2e62 |
</variablelist>
|
|
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6f2e62 |
<variablelist remap='TP'>
|
|
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<varlistentry>
|
|
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<term><emphasis remap='B'>ipv6-sitelocal</emphasis></term>
|
|
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6f2e62 |
<listitem>
|
|
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6f2e62 |
<para>Request IPv6 site-local addresses.</para>
|
|
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6f2e62 |
</listitem>
|
|
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6f2e62 |
</varlistentry>
|
|
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6f2e62 |
</variablelist>
|
|
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6f2e62 |
<variablelist remap='TP'>
|
|
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6f2e62 |
<varlistentry>
|
|
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6f2e62 |
<term><emphasis remap='B'>ipv6-linklocal</emphasis></term>
|
|
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6f2e62 |
<listitem>
|
|
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6f2e62 |
<para>Request IPv6 link-local addresses.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
</variablelist>
|
|
Packit Service |
6f2e62 |
<variablelist remap='TP'>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><emphasis remap='B'>ipv6-all</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Request IPv6 addresses on other interfaces.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
</variablelist>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
</variablelist>
|
|
Packit Service |
6f2e62 |
<variablelist remap='TP'>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><emphasis remap='B'>ipv4</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Queries for IPv4 Addresses. There is one IPv4 specific flag.</para>
|
|
Packit Service |
6f2e62 |
<variablelist remap='TP'>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><emphasis remap='B'>ipv4-all</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Request IPv4 addresses on other interfaces.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
</variablelist>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
</variablelist>
|
|
Packit Service |
6f2e62 |
<variablelist remap='TP'>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><emphasis remap='B'>subject-ipv6=</emphasis><emphasis remap='I'>ipv6addr</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>IPv6 subject address.</para>
|
|
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6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
</variablelist>
|
|
Packit Service |
6f2e62 |
<variablelist remap='TP'>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><emphasis remap='B'>subject-ipv4=</emphasis><emphasis remap='I'>ipv4addr</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>IPv4 subject address.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
</variablelist>
|
|
Packit Service |
6f2e62 |
<variablelist remap='TP'>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><emphasis remap='B'>subject-name=</emphasis><emphasis remap='I'>nodename</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Subject name. If it contains more than one dot,
|
|
Packit Service |
6f2e62 |
fully-qualified domain name is assumed.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
</variablelist>
|
|
Packit Service |
6f2e62 |
<variablelist remap='TP'>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><emphasis remap='B'>subject-fqdn=</emphasis><emphasis remap='I'>nodename</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Subject name. Fully-qualified domain name is
|
|
Packit Service |
6f2e62 |
always assumed.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
</variablelist>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-n</option></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Numeric output only.
|
|
Packit Service |
6f2e62 |
No attempt will be made to lookup symbolic names for host addresses.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-O</option></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Report outstanding ICMP ECHO reply before sending next packet.
|
|
Packit Service |
6f2e62 |
This is useful together with the timestamp <option>-D</option> to
|
|
Packit Service |
6f2e62 |
log output to a diagnostic file and search for missing answers.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-p </option><emphasis remap='I'>pattern</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>You may specify up to 16 “pad” bytes to fill out the packet you send.
|
|
Packit Service |
6f2e62 |
This is useful for diagnosing data-dependent problems in a network.
|
|
Packit Service |
6f2e62 |
For example, <option>-p ff</option> will cause the sent packet
|
|
Packit Service |
6f2e62 |
to be filled with all ones.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-q</option></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Quiet output.
|
|
Packit Service |
6f2e62 |
Nothing is displayed except the summary lines at startup time and
|
|
Packit Service |
6f2e62 |
when finished.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-Q </option><emphasis remap='I'>tos</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Set Quality of Service -related bits in ICMP datagrams.
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>tos</emphasis> can be decimal (<command>ping</command> only) or hex number.</para>
|
|
Packit Service |
6f2e62 |
|
|
Packit Service |
6f2e62 |
<para>In RFC2474, these fields are interpreted as 8-bit Differentiated
|
|
Packit Service |
6f2e62 |
Services (DS), consisting of: bits 0-1 (2 lowest bits) of separate
|
|
Packit Service |
6f2e62 |
data, and bits 2-7 (highest 6 bits) of Differentiated Services
|
|
Packit Service |
6f2e62 |
Codepoint (DSCP). In RFC2481 and RFC3168, bits 0-1 are used for ECN.</para>
|
|
Packit Service |
6f2e62 |
|
|
Packit Service |
6f2e62 |
<para>Historically (RFC1349, obsoleted by RFC2474), these were interpreted
|
|
Packit Service |
6f2e62 |
as: bit 0 (lowest bit) for reserved (currently being redefined as
|
|
Packit Service |
6f2e62 |
congestion control), 1-4 for Type of Service and bits 5-7
|
|
Packit Service |
6f2e62 |
(highest bits) for Precedence.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-r</option></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Bypass the normal routing tables and send directly to a host on an attached
|
|
Packit Service |
6f2e62 |
interface.
|
|
Packit Service |
6f2e62 |
If the host is not on a directly-attached network, an error is returned.
|
|
Packit Service |
6f2e62 |
This option can be used to ping a local host through an interface
|
|
Packit Service |
6f2e62 |
that has no route through it provided the option <option>-I</option> is also
|
|
Packit Service |
6f2e62 |
used.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-R</option></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para><command>ping</command> only.
|
|
Packit Service |
6f2e62 |
Record route.
|
|
Packit Service |
6f2e62 |
Includes the RECORD_ROUTE option in the ECHO_REQUEST
|
|
Packit Service |
6f2e62 |
packet and displays the route buffer on returned packets.
|
|
Packit Service |
6f2e62 |
Note that the IP header is only large enough for nine such routes.
|
|
Packit Service |
6f2e62 |
Many hosts ignore or discard this option.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-s </option><emphasis remap='I'>packetsize</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Specifies the number of data bytes to be sent.
|
|
Packit Service |
6f2e62 |
The default is 56, which translates into 64 ICMP
|
|
Packit Service |
6f2e62 |
data bytes when combined with the 8 bytes of ICMP header data.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-S </option><emphasis remap='I'>sndbuf</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Set socket sndbuf. If not specified, it is selected to buffer
|
|
Packit Service |
6f2e62 |
not more than one packet.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-t </option><emphasis remap='I'>ttl</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para><command>ping</command> only.
|
|
Packit Service |
6f2e62 |
Set the IP Time to Live.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-T </option><emphasis remap='I'>timestamp option</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Set special IP timestamp options.
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>timestamp option</emphasis> may be either
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>tsonly</emphasis> (only timestamps),
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>tsandaddr</emphasis> (timestamps and addresses) or
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>tsprespec host1 [host2 [host3 [host4]]]</emphasis>
|
|
Packit Service |
6f2e62 |
(timestamp prespecified hops).</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-U</option></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Print full user-to-user latency (the old behaviour). Normally
|
|
Packit Service |
6f2e62 |
<command>ping</command>
|
|
Packit Service |
6f2e62 |
prints network round trip time, which can be different
|
|
Packit Service |
6f2e62 |
f.e. due to DNS failures.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-v</option></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Verbose output.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-V</option></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Show version and exit.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-w </option><emphasis remap='I'>deadline</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Specify a timeout, in seconds, before
|
|
Packit Service |
6f2e62 |
<command>ping</command>
|
|
Packit Service |
6f2e62 |
exits regardless of how many
|
|
Packit Service |
6f2e62 |
packets have been sent or received. In this case
|
|
Packit Service |
6f2e62 |
<command>ping</command>
|
|
Packit Service |
6f2e62 |
does not stop after
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>count</emphasis>
|
|
Packit Service |
6f2e62 |
packet are sent, it waits either for
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>deadline</emphasis>
|
|
Packit Service |
6f2e62 |
expire or until
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>count</emphasis>
|
|
Packit Service |
6f2e62 |
probes are answered or for some error notification from network.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
<varlistentry>
|
|
Packit Service |
6f2e62 |
<term><option>-W </option><emphasis remap='I'>timeout</emphasis></term>
|
|
Packit Service |
6f2e62 |
<listitem>
|
|
Packit Service |
6f2e62 |
<para>Time to wait for a response, in seconds. The option affects only timeout
|
|
Packit Service |
6f2e62 |
in absence of any responses, otherwise <command>ping</command> waits for two RTTs.</para>
|
|
Packit Service |
6f2e62 |
</listitem>
|
|
Packit Service |
6f2e62 |
</varlistentry>
|
|
Packit Service |
6f2e62 |
</variablelist>
|
|
Packit Service |
6f2e62 |
<para>When using <command>ping</command> for fault isolation, it should first be run
|
|
Packit Service |
6f2e62 |
on the local host, to verify that the local network interface is up
|
|
Packit Service |
6f2e62 |
and running. Then, hosts and gateways further and further away should be
|
|
Packit Service |
6f2e62 |
“pinged”. Round-trip times and packet loss statistics are computed.
|
|
Packit Service |
6f2e62 |
If duplicate packets are received, they are not included in the packet
|
|
Packit Service |
6f2e62 |
loss calculation, although the round trip time of these packets is used
|
|
Packit Service |
6f2e62 |
in calculating the minimum/average/maximum/mdev round-trip time numbers.
|
|
Packit Service |
6f2e62 |
</para>
|
|
Packit Service |
6f2e62 |
<para>
|
|
Packit Service |
6f2e62 |
Median deviation (mdev), essentially an average of how far each ping RTT is from the mean RTT. The higher mdev is, the more variable the RTT is (over time).
|
|
Packit Service |
6f2e62 |
|
|
Packit Service |
6f2e62 |
With a high RTT variability, you will have speed issues with bulk transfers (they will take longer than is strictly speaking necessary, as the variability will eventually cause the sender to wait for ACKs) and you will have middling to poor VoIP quality.
|
|
Packit Service |
6f2e62 |
</para>
|
|
Packit Service |
6f2e62 |
<para>
|
|
Packit Service |
6f2e62 |
When the specified number of packets have been sent (and received) or
|
|
Packit Service |
6f2e62 |
if the program is terminated with a
|
|
Packit Service |
6f2e62 |
SIGINT, a brief summary is displayed. Shorter current statistics
|
|
Packit Service |
6f2e62 |
can be obtained without termination of process with signal
|
|
Packit Service |
6f2e62 |
SIGQUIT.</para>
|
|
Packit Service |
6f2e62 |
|
|
Packit Service |
6f2e62 |
<para>If <command>ping</command> does not receive any reply packets at all it will
|
|
Packit Service |
6f2e62 |
exit with code 1. If a packet
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>count</emphasis>
|
|
Packit Service |
6f2e62 |
and
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>deadline</emphasis>
|
|
Packit Service |
6f2e62 |
are both specified, and fewer than
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>count</emphasis>
|
|
Packit Service |
6f2e62 |
packets are received by the time the
|
|
Packit Service |
6f2e62 |
<emphasis remap='I'>deadline</emphasis>
|
|
Packit Service |
6f2e62 |
has arrived, it will also exit with code 1.
|
|
Packit Service |
6f2e62 |
On other error it exits with code 2. Otherwise it exits with code 0. This
|
|
Packit Service |
6f2e62 |
makes it possible to use the exit code to see if a host is alive or
|
|
Packit Service |
6f2e62 |
not.</para>
|
|
Packit Service |
6f2e62 |
|
|
Packit Service |
6f2e62 |
<para>This program is intended for use in network testing, measurement and
|
|
Packit Service |
6f2e62 |
management.
|
|
Packit Service |
6f2e62 |
Because of the load it can impose on the network, it is unwise to use
|
|
Packit Service |
6f2e62 |
<command>ping</command> during normal operations or from automated scripts.</para>
|
|
Packit Service |
6f2e62 |
</refsect1>
|
|
Packit Service |
6f2e62 |
|
|
Packit Service |
6f2e62 |
<refsect1 id='icmp_packet_details'><title>ICMP PACKET DETAILS</title>
|
|
Packit Service |
6f2e62 |
<para>An IP header without options is 20 bytes.
|
|
Packit Service |
6f2e62 |
An ICMP ECHO_REQUEST packet contains an additional 8 bytes worth
|
|
Packit Service |
6f2e62 |
of ICMP header followed by an arbitrary amount of data.
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When a <emphasis remap='I'>packetsize</emphasis> is given, this indicated the size of this
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extra piece of data (the default is 56). Thus the amount of data received
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inside of an IP packet of type ICMP ECHO_REPLY will always be 8 bytes
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more than the requested data space (the ICMP header).</para>
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<para>If the data space is at least of size of struct timeval
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<command>ping</command> uses the beginning bytes of this space to include
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a timestamp which it uses in the computation of round trip times.
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If the data space is shorter, no round trip times are given.</para>
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</refsect1>
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<refsect1 id='duplicate_and_damaged_packets'><title>DUPLICATE AND DAMAGED PACKETS</title>
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<para><command>ping</command> will report duplicate and damaged packets.
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Duplicate packets should never occur, and seem to be caused by
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inappropriate link-level retransmissions.
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Duplicates may occur in many situations and are rarely (if ever) a
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good sign, although the presence of low levels of duplicates may not
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always be cause for alarm.</para>
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<para>Damaged packets are obviously serious cause for alarm and often
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indicate broken hardware somewhere in the
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<command>ping</command> packet's path (in the network or in the hosts).</para>
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</refsect1>
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<refsect1 id='trying_different_data_patterns'>
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<title>TRYING DIFFERENT DATA PATTERNS</title>
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<para>The (inter)network layer should never treat packets differently depending
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on the data contained in the data portion.
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Unfortunately, data-dependent problems have been known to sneak into
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networks and remain undetected for long periods of time.
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In many cases the particular pattern that will have problems is something
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that doesn't have sufficient “transitions”, such as all ones or all
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zeros, or a pattern right at the edge, such as almost all zeros.
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It isn't necessarily enough to specify a data pattern of all zeros (for
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example) on the command line because the pattern that is of interest is
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at the data link level, and the relationship between what you type and
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what the controllers transmit can be complicated.</para>
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<para>This means that if you have a data-dependent problem you will probably
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have to do a lot of testing to find it.
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If you are lucky, you may manage to find a file that either can't be sent
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across your network or that takes much longer to transfer than other
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similar length files.
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You can then examine this file for repeated patterns that you can test
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using the <option>-p</option> option of <command>ping</command>.</para>
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</refsect1>
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<refsect1 id='ttl_details'><title>TTL DETAILS</title>
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<para>The TTL value of an IP packet represents the maximum number of IP routers
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that the packet can go through before being thrown away.
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In current practice you can expect each router in the Internet to decrement
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the TTL field by exactly one.</para>
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<para>The TCP/IP specification states that the TTL field for TCP
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packets should be set to 60, but many systems use smaller values
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(4.3 BSD uses 30, 4.2 used 15).</para>
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<para>The maximum possible value of this field is 255, and most Unix systems set
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the TTL field of ICMP ECHO_REQUEST packets to 255.
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This is why you will find you can “ping” some hosts, but not reach them
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with
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<citerefentry><refentrytitle>telnet</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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or
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<citerefentry><refentrytitle>ftp</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
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<para>In normal operation ping prints the TTL value from the packet it receives.
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When a remote system receives a ping packet, it can do one of three things
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with the TTL field in its response:</para>
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<variablelist remap='TP'>
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<varlistentry>
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<listitem>
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<para>• Not change it; this is what Berkeley Unix systems did before the
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4.3BSD Tahoe release. In this case the TTL value in the received packet
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will be 255 minus the number of routers in the round-trip path.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<listitem>
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<para>• Set it to 255; this is what current Berkeley Unix systems do.
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In this case the TTL value in the received packet will be 255 minus the
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number of routers in the path <emphasis remap='B'>from</emphasis>
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the remote system <emphasis remap='B'>to</emphasis> the <command>ping</command>ing host.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<listitem>
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<para>• Set it to some other value. Some machines use the same value for
|
|
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ICMP packets that they use for TCP packets, for example either 30 or 60.
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Others may use completely wild values.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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|
|
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<refsect1 id='bugs'><title>BUGS</title>
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<variablelist remap='TP'>
|
|
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<varlistentry>
|
|
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<listitem>
|
|
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<para>• Many Hosts and Gateways ignore the RECORD_ROUTE option.</para>
|
|
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</listitem>
|
|
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</varlistentry>
|
|
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<varlistentry>
|
|
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<listitem>
|
|
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<para>• The maximum IP header length is too small for options like
|
|
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RECORD_ROUTE to be completely useful.
|
|
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There's not much that can be done about this, however.</para>
|
|
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</listitem>
|
|
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</varlistentry>
|
|
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<varlistentry>
|
|
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<listitem>
|
|
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<para>• Flood pinging is not recommended in general, and flood pinging the
|
|
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6f2e62 |
broadcast address should only be done under very controlled conditions.</para>
|
|
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6f2e62 |
</listitem>
|
|
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</varlistentry>
|
|
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</variablelist>
|
|
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</refsect1>
|
|
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|
|
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<refsect1 id='see_also'>
|
|
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<title>SEE ALSO</title>
|
|
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<para><citerefentry><refentrytitle>ip</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
|
|
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6f2e62 |
<citerefentry><refentrytitle>ss</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
|
|
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</refsect1>
|
|
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|
|
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<refsect1 id='history'>
|
|
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<title>HISTORY</title>
|
|
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<para>The <command>ping</command> command appeared in 4.3BSD.</para>
|
|
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6f2e62 |
|
|
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6f2e62 |
<para>The version described here is its descendant specific to Linux.</para>
|
|
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6f2e62 |
|
|
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6f2e62 |
<para>As of version s20150815, the <emphasis remap='B'>ping6</emphasis> binary doesn't exist anymore.
|
|
Packit Service |
6f2e62 |
It has been merged into <command>ping</command>. Creating a symlink named
|
|
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6f2e62 |
<emphasis remap='B'>ping6</emphasis> pointing to <command>ping</command> will result in the same
|
|
Packit Service |
6f2e62 |
funcionality as before.</para>
|
|
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6f2e62 |
</refsect1>
|
|
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|
|
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<refsect1 id='security'>
|
|
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<title>SECURITY</title>
|
|
Packit Service |
6f2e62 |
<para><command>ping</command> requires CAP_NET_RAW capability
|
|
Packit Service |
6f2e62 |
to be executed 1) if the program is used for non-echo queries
|
|
Packit Service |
6f2e62 |
(See <option>-N</option> option), or 2) if kernel does not
|
|
Packit Service |
6f2e62 |
support non-raw ICMP sockets, or 3) if the user is not allowed
|
|
Packit Service |
6f2e62 |
to create an ICMP echo socket. The program may be used as
|
|
Packit Service |
6f2e62 |
set-uid root.</para>
|
|
Packit Service |
6f2e62 |
</refsect1>
|
|
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6f2e62 |
|
|
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6f2e62 |
<refsect1 id='availability'>
|
|
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<title>AVAILABILITY</title>
|
|
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6f2e62 |
<para><command>ping</command> is part of <emphasis remap='I'>iputils</emphasis> package.</para>
|
|
Packit Service |
6f2e62 |
</refsect1>
|
|
Packit Service |
6f2e62 |
</refentry>
|