path: root/upstream/debian-unstable/man3/Net::Ping.3perl

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.\" ========================================================================
.\"
.IX Title "Net::Ping 3perl"
.TH Net::Ping 3perl 2024-05-30 "perl v5.38.2" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
Net::Ping \- check a remote host for reachability
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&    use Net::Ping;
\&
\&    my $p = Net::Ping\->new();
\&    print "$host is alive.\en" if $p\->ping($host);
\&    $p\->close();
\&
\&    my $p = Net::Ping\->new("icmp");
\&    $p\->bind($my_addr); # Specify source interface of pings
\&    foreach my $host (@host_array)
\&    {
\&        print "$host is ";
\&        print "NOT " unless $p\->ping($host, 2);
\&        print "reachable.\en";
\&        sleep(1);
\&    }
\&    $p\->close();
\&
\&    my $p = Net::Ping\->new("icmpv6");
\&    my $ip = "[fd00:dead:beef::4e]";
\&    print "$ip is alive.\en" if $p\->ping($ip);
\&
\&    my $p = Net::Ping\->new("tcp", 2);
\&    # Try connecting to the www port instead of the echo port
\&    $p\->port_number(scalar(getservbyname("http", "tcp")));
\&    while ($stop_time > time())
\&    {
\&        print "$host not reachable ", scalar(localtime()), "\en"
\&            unless $p\->ping($host);
\&        sleep(300);
\&    }
\&    undef($p);
\&
\&    # Like tcp protocol, but with many hosts
\&    my $p = Net::Ping\->new("syn");
\&    $p\->port_number(getservbyname("http", "tcp"));
\&    foreach my $host (@host_array) {
\&      $p\->ping($host);
\&    }
\&    while (my ($host, $rtt, $ip) = $p\->ack) {
\&      print "HOST: $host [$ip] ACKed in $rtt seconds.\en";
\&    }
\&
\&    # High precision syntax (requires Time::HiRes)
\&    my $p = Net::Ping\->new();
\&    $p\->hires();
\&    my ($ret, $duration, $ip) = $p\->ping($host, 5.5);
\&    printf("$host [ip: $ip] is alive (packet return time: %.2f ms)\en",
\&            1000 * $duration)
\&      if $ret;
\&    $p\->close();
\&
\&    # For backward compatibility
\&    print "$host is alive.\en" if pingecho($host);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
This module contains methods to test the reachability of remote
hosts on a network.  A ping object is first created with optional
parameters, a variable number of hosts may be pinged multiple
times and then the connection is closed.
.PP
You may choose one of six different protocols to use for the
ping. The "tcp" protocol is the default. Note that a live remote host
may still fail to be pingable by one or more of these protocols. For
example, www.microsoft.com is generally alive but not "icmp" pingable.
.PP
With the "tcp" protocol the \fBping()\fR method attempts to establish a
connection to the remote host's echo port.  If the connection is
successfully established, the remote host is considered reachable.  No
data is actually echoed.  This protocol does not require any special
privileges but has higher overhead than the "udp" and "icmp" protocols.
.PP
Specifying the "udp" protocol causes the \fBping()\fR method to send a udp
packet to the remote host's echo port.  If the echoed packet is
received from the remote host and the received packet contains the
same data as the packet that was sent, the remote host is considered
reachable.  This protocol does not require any special privileges.
It should be borne in mind that, for a udp ping, a host
will be reported as unreachable if it is not running the
appropriate echo service.  For Unix-like systems see \fBinetd\fR\|(8)
for more information.
.PP
If the "icmp" protocol is specified, the \fBping()\fR method sends an icmp
echo message to the remote host, which is what the UNIX ping program
does.  If the echoed message is received from the remote host and
the echoed information is correct, the remote host is considered
reachable.  Specifying the "icmp" protocol requires that the program
be run as root or that the program be setuid to root.
.PP
If the "external" protocol is specified, the \fBping()\fR method attempts to
use the \f(CW\*(C`Net::Ping::External\*(C'\fR module to ping the remote host.
\&\f(CW\*(C`Net::Ping::External\*(C'\fR interfaces with your system's default \f(CW\*(C`ping\*(C'\fR
utility to perform the ping, and generally produces relatively
accurate results. If \f(CW\*(C`Net::Ping::External\*(C'\fR if not installed on your
system, specifying the "external" protocol will result in an error.
.PP
If the "syn" protocol is specified, the "ping" method will only
send a TCP SYN packet to the remote host then immediately return.
If the syn packet was sent successfully, it will return a true value,
otherwise it will return false.  NOTE: Unlike the other protocols,
the return value does NOT determine if the remote host is alive or
not since the full TCP three-way handshake may not have completed
yet.  The remote host is only considered reachable if it receives
a TCP ACK within the timeout specified.  To begin waiting for the
ACK packets, use the "ack" method as explained below.  Use the
"syn" protocol instead the "tcp" protocol to determine reachability
of multiple destinations simultaneously by sending parallel TCP
SYN packets.  It will not block while testing each remote host.
This protocol does not require any special privileges.
.SS Functions
.IX Subsection "Functions"
.IP "Net::Ping\->new([proto, timeout, bytes, device, tos, ttl, family, host, port, bind, gateway, retrans, pingstring, source_verify econnrefused dontfrag IPV6_USE_MIN_MTU IPV6_RECVPATHMTU])" 4
.IX Xref "new"
.IX Item "Net::Ping->new([proto, timeout, bytes, device, tos, ttl, family, host, port, bind, gateway, retrans, pingstring, source_verify econnrefused dontfrag IPV6_USE_MIN_MTU IPV6_RECVPATHMTU])"
Create a new ping object.  All of the parameters are optional and can
be passed as hash ref.  All options besides the first 7 must be passed
as hash ref.
.Sp
\&\f(CW\*(C`proto\*(C'\fR specifies the protocol to use when doing a ping.  The current
choices are "tcp", "udp", "icmp", "icmpv6", "stream", "syn", or
"external".  The default is "tcp".
.Sp
If a \f(CW\*(C`timeout\*(C'\fR in seconds is provided, it is used
when a timeout is not given to the \fBping()\fR method (below).  The timeout
must be greater than 0 and the default, if not specified, is 5 seconds.
.Sp
If the number of data bytes (\f(CW\*(C`bytes\*(C'\fR) is given, that many data bytes
are included in the ping packet sent to the remote host. The number of
data bytes is ignored if the protocol is "tcp".  The minimum (and
default) number of data bytes is 1 if the protocol is "udp" and 0
otherwise.  The maximum number of data bytes that can be specified is
65535, but staying below the MTU (1472 bytes for ICMP) is recommended.
Many small devices cannot deal with fragmented ICMP packets.
.Sp
If \f(CW\*(C`device\*(C'\fR is given, this device is used to bind the source endpoint
before sending the ping packet.  I believe this only works with
superuser privileges and with udp and icmp protocols at this time.
.Sp
If <tos> is given, this ToS is configured into the socket.
.Sp
For icmp, \f(CW\*(C`ttl\*(C'\fR can be specified to set the TTL of the outgoing packet.
.Sp
Valid \f(CW\*(C`family\*(C'\fR values for IPv4:
.Sp
.Vb 1
\&   4, v4, ip4, ipv4, AF_INET (constant)
.Ve
.Sp
Valid \f(CW\*(C`family\*(C'\fR values for IPv6:
.Sp
.Vb 1
\&   6, v6, ip6, ipv6, AF_INET6 (constant)
.Ve
.Sp
The \f(CW\*(C`host\*(C'\fR argument implicitly specifies the family if the family
argument is not given.
.Sp
The \f(CW\*(C`port\*(C'\fR argument is only valid for a udp, tcp or stream ping, and will not
do what you think it does. ping returns true when we get a "Connection refused"!
The default is the echo port.
.Sp
The \f(CW\*(C`bind\*(C'\fR argument specifies the local_addr to bind to.
By specifying a bind argument you don't need the bind method.
.Sp
The \f(CW\*(C`gateway\*(C'\fR argument is only valid for IPv6, and requires a IPv6
address.
.Sp
The \f(CW\*(C`retrans\*(C'\fR argument the exponential backoff rate, default 1.2.
It matches the \f(CW$def_factor\fR global.
.Sp
The \f(CW\*(C`dontfrag\*(C'\fR argument sets the IP_DONTFRAG bit, but note that
IP_DONTFRAG is not yet defined by Socket, and not available on many
systems. Then it is ignored. On linux it also sets IP_MTU_DISCOVER to
IP_PMTUDISC_DO but need we don't chunk oversized packets. You need to
set \f(CW$data_size\fR manually.
.ie n .IP "$p\->ping($host [, $timeout [, $family]]);" 4
.el .IP "\f(CW$p\fR\->ping($host [, \f(CW$timeout\fR [, \f(CW$family\fR]]);" 4
.IX Xref "ping"
.IX Item "$p->ping($host [, $timeout [, $family]]);"
Ping the remote host and wait for a response.  \f(CW$host\fR can be either the
hostname or the IP number of the remote host.  The optional timeout
must be greater than 0 seconds and defaults to whatever was specified
when the ping object was created.  Returns a success flag.  If the
hostname cannot be found or there is a problem with the IP number, the
success flag returned will be undef.  Otherwise, the success flag will
be 1 if the host is reachable and 0 if it is not.  For most practical
purposes, undef and 0 and can be treated as the same case.  In array
context, the elapsed time as well as the string form of the ip the
host resolved to are also returned.  The elapsed time value will
be a float, as returned by the \fBTime::HiRes::time()\fR function, if \fBhires()\fR
has been previously called, otherwise it is returned as an integer.
.ie n .IP "$p\->source_verify( { 0 | 1 } );" 4
.el .IP "\f(CW$p\fR\->source_verify( { 0 | 1 } );" 4
.IX Xref "source_verify"
.IX Item "$p->source_verify( { 0 | 1 } );"
Allows source endpoint verification to be enabled or disabled.
This is useful for those remote destinations with multiples
interfaces where the response may not originate from the same
endpoint that the original destination endpoint was sent to.
This only affects udp and icmp protocol pings.
.Sp
This is enabled by default.
.ie n .IP "$p\->service_check( { 0 | 1 } );" 4
.el .IP "\f(CW$p\fR\->service_check( { 0 | 1 } );" 4
.IX Xref "service_check"
.IX Item "$p->service_check( { 0 | 1 } );"
Set whether or not the connect behavior should enforce
remote service availability as well as reachability.  Normally,
if the remote server reported ECONNREFUSED, it must have been
reachable because of the status packet that it reported.
With this option enabled, the full three-way tcp handshake
must have been established successfully before it will
claim it is reachable.  NOTE:  It still does nothing more
than connect and disconnect.  It does not speak any protocol
(i.e., HTTP or FTP) to ensure the remote server is sane in
any way.  The remote server CPU could be grinding to a halt
and unresponsive to any clients connecting, but if the kernel
throws the ACK packet, it is considered alive anyway.  To
really determine if the server is responding well would be
application specific and is beyond the scope of Net::Ping.
For udp protocol, enabling this option demands that the
remote server replies with the same udp data that it was sent
as defined by the udp echo service.
.Sp
This affects the "udp", "tcp", and "syn" protocols.
.Sp
This is disabled by default.
.ie n .IP "$p\->tcp_service_check( { 0 | 1 } );" 4
.el .IP "\f(CW$p\fR\->tcp_service_check( { 0 | 1 } );" 4
.IX Xref "tcp_service_check"
.IX Item "$p->tcp_service_check( { 0 | 1 } );"
Deprecated method, but does the same as \fBservice_check()\fR method.
.ie n .IP "$p\->hires( { 0 | 1 } );" 4
.el .IP "\f(CW$p\fR\->hires( { 0 | 1 } );" 4
.IX Xref "hires"
.IX Item "$p->hires( { 0 | 1 } );"
With 1 causes this module to use Time::HiRes module, allowing milliseconds
to be returned by subsequent calls to \fBping()\fR.
.ie n .IP $p\->time 4
.el .IP \f(CW$p\fR\->time 4
.IX Xref "time"
.IX Item "$p->time"
The current time, hires or not.
.ie n .IP "$p\->socket_blocking_mode( $fh, $mode );" 4
.el .IP "\f(CW$p\fR\->socket_blocking_mode( \f(CW$fh\fR, \f(CW$mode\fR );" 4
.IX Xref "socket_blocking_mode"
.IX Item "$p->socket_blocking_mode( $fh, $mode );"
Sets or clears the O_NONBLOCK flag on a file handle.
.ie n .IP $p\->IPV6_USE_MIN_MTU 4
.el .IP \f(CW$p\fR\->IPV6_USE_MIN_MTU 4
.IX Xref "IPV6_USE_MIN_MTU"
.IX Item "$p->IPV6_USE_MIN_MTU"
With argument sets the option.
Without returns the option value.
.ie n .IP $p\->IPV6_RECVPATHMTU 4
.el .IP \f(CW$p\fR\->IPV6_RECVPATHMTU 4
.IX Xref "IPV6_RECVPATHMTU"
.IX Item "$p->IPV6_RECVPATHMTU"
Notify an according IPv6 MTU.
.Sp
With argument sets the option.
Without returns the option value.
.ie n .IP $p\->IPV6_HOPLIMIT 4
.el .IP \f(CW$p\fR\->IPV6_HOPLIMIT 4
.IX Xref "IPV6_HOPLIMIT"
.IX Item "$p->IPV6_HOPLIMIT"
With argument sets the option.
Without returns the option value.
.ie n .IP "$p\->IPV6_REACHCONF \fINYI\fR" 4
.el .IP "\f(CW$p\fR\->IPV6_REACHCONF \fINYI\fR" 4
.IX Xref "IPV6_REACHCONF"
.IX Item "$p->IPV6_REACHCONF NYI"
Sets ipv6 reachability
IPV6_REACHCONF was removed in RFC3542. ping6 \-R supports it.
IPV6_REACHCONF requires root/admin permissions.
.Sp
With argument sets the option.
Without returns the option value.
.Sp
Not yet implemented.
.ie n .IP $p\->bind($local_addr); 4
.el .IP \f(CW$p\fR\->bind($local_addr); 4
.IX Xref "bind"
.IX Item "$p->bind($local_addr);"
Sets the source address from which pings will be sent.  This must be
the address of one of the interfaces on the local host.  \f(CW$local_addr\fR
may be specified as a hostname or as a text IP address such as
"192.168.1.1".
.Sp
If the protocol is set to "tcp", this method may be called any
number of times, and each call to the \fBping()\fR method (below) will use
the most recent \f(CW$local_addr\fR.  If the protocol is "icmp" or "udp",
then \fBbind()\fR must be called at most once per object, and (if it is
called at all) must be called before the first call to \fBping()\fR for that
object.
.Sp
The \fBbind()\fR call can be omitted when specifying the \f(CW\*(C`bind\*(C'\fR option to
\&\fBnew()\fR.
.ie n .IP $p\->message_type([$ping_type]); 4
.el .IP \f(CW$p\fR\->message_type([$ping_type]); 4
.IX Xref "message_type"
.IX Item "$p->message_type([$ping_type]);"
When you are using the "icmp" protocol, this call permit to change the
message type to 'echo' or 'timestamp' (only for IPv4, see RFC 792).
.Sp
Without argument, it returns the currently used icmp protocol message type.
By default, it returns 'echo'.
.ie n .IP $p\->open($host); 4
.el .IP \f(CW$p\fR\->open($host); 4
.IX Xref "open"
.IX Item "$p->open($host);"
When you are using the "stream" protocol, this call pre-opens the
tcp socket.  It's only necessary to do this if you want to
provide a different timeout when creating the connection, or
remove the overhead of establishing the connection from the
first ping.  If you don't call \f(CWopen()\fR, the connection is
automatically opened the first time \f(CWping()\fR is called.
This call simply does nothing if you are using any protocol other
than stream.
.Sp
The \f(CW$host\fR argument can be omitted when specifying the \f(CW\*(C`host\*(C'\fR option to
\&\fBnew()\fR.
.ie n .IP "$p\->ack( [ $host ] );" 4
.el .IP "\f(CW$p\fR\->ack( [ \f(CW$host\fR ] );" 4
.IX Xref "ack"
.IX Item "$p->ack( [ $host ] );"
When using the "syn" protocol, use this method to determine
the reachability of the remote host.  This method is meant
to be called up to as many times as \fBping()\fR was called.  Each
call returns the host (as passed to \fBping()\fR) that came back
with the TCP ACK.  The order in which the hosts are returned
may not necessarily be the same order in which they were
SYN queued using the \fBping()\fR method.  If the timeout is
reached before the TCP ACK is received, or if the remote
host is not listening on the port attempted, then the TCP
connection will not be established and \fBack()\fR will return
undef.  In list context, the host, the ack time, the dotted ip 
string, and the port number will be returned instead of just the host.
If the optional \f(CW$host\fR argument is specified, the return
value will be pertaining to that host only.
This call simply does nothing if you are using any protocol
other than "syn".
.Sp
When "new" had a host option, this host will be used.
Without \f(CW$host\fR argument, all hosts are scanned.
.ie n .IP "$p\->nack( $failed_ack_host );" 4
.el .IP "\f(CW$p\fR\->nack( \f(CW$failed_ack_host\fR );" 4
.IX Xref "nack"
.IX Item "$p->nack( $failed_ack_host );"
The reason that \f(CW\*(C`host $failed_ack_host\*(C'\fR did not receive a
valid ACK.  Useful to find out why when \f(CWack($fail_ack_host)\fR
returns a false value.
.ie n .IP $p\->ack_unfork($host) 4
.el .IP \f(CW$p\fR\->ack_unfork($host) 4
.IX Xref "ack_unfork"
.IX Item "$p->ack_unfork($host)"
The variant called by "ack" with the "syn" protocol and \f(CW$syn_forking\fR
enabled.
.ie n .IP "$p\->ping_icmp([$host, $timeout, $family])" 4
.el .IP "\f(CW$p\fR\->ping_icmp([$host, \f(CW$timeout\fR, \f(CW$family\fR])" 4
.IX Xref "ping_icmp"
.IX Item "$p->ping_icmp([$host, $timeout, $family])"
The "ping" method used with the icmp protocol.
.ie n .IP "$p\->ping_icmpv6([$host, $timeout, $family])" 4
.el .IP "\f(CW$p\fR\->ping_icmpv6([$host, \f(CW$timeout\fR, \f(CW$family\fR])" 4
.IX Xref "ping_icmpv6"
.IX Item "$p->ping_icmpv6([$host, $timeout, $family])"
The "ping" method used with the icmpv6 protocol.
.ie n .IP "$p\->ping_stream([$host, $timeout, $family])" 4
.el .IP "\f(CW$p\fR\->ping_stream([$host, \f(CW$timeout\fR, \f(CW$family\fR])" 4
.IX Xref "ping_stream"
.IX Item "$p->ping_stream([$host, $timeout, $family])"
The "ping" method used with the stream protocol.
.Sp
Perform a stream ping.  If the tcp connection isn't
already open, it opens it.  It then sends some data and waits for
a reply.  It leaves the stream open on exit.
.ie n .IP "$p\->ping_syn([$host, $ip, $start_time, $stop_time])" 4
.el .IP "\f(CW$p\fR\->ping_syn([$host, \f(CW$ip\fR, \f(CW$start_time\fR, \f(CW$stop_time\fR])" 4
.IX Xref "ping_syn"
.IX Item "$p->ping_syn([$host, $ip, $start_time, $stop_time])"
The "ping" method used with the syn protocol.
Sends a TCP SYN packet to host specified.
.ie n .IP "$p\->ping_syn_fork([$host, $timeout, $family])" 4
.el .IP "\f(CW$p\fR\->ping_syn_fork([$host, \f(CW$timeout\fR, \f(CW$family\fR])" 4
.IX Xref "ping_syn_fork"
.IX Item "$p->ping_syn_fork([$host, $timeout, $family])"
The "ping" method used with the forking syn protocol.
.ie n .IP "$p\->ping_tcp([$host, $timeout, $family])" 4
.el .IP "\f(CW$p\fR\->ping_tcp([$host, \f(CW$timeout\fR, \f(CW$family\fR])" 4
.IX Xref "ping_tcp"
.IX Item "$p->ping_tcp([$host, $timeout, $family])"
The "ping" method used with the tcp protocol.
.ie n .IP "$p\->ping_udp([$host, $timeout, $family])" 4
.el .IP "\f(CW$p\fR\->ping_udp([$host, \f(CW$timeout\fR, \f(CW$family\fR])" 4
.IX Xref "ping_udp"
.IX Item "$p->ping_udp([$host, $timeout, $family])"
The "ping" method used with the udp protocol.
.Sp
Perform a udp echo ping.  Construct a message of
at least the one-byte sequence number and any additional data bytes.
Send the message out and wait for a message to come back.  If we
get a message, make sure all of its parts match.  If they do, we are
done.  Otherwise go back and wait for the message until we run out
of time.  Return the result of our efforts.
.ie n .IP "$p\->ping_external([$host, $timeout, $family])" 4
.el .IP "\f(CW$p\fR\->ping_external([$host, \f(CW$timeout\fR, \f(CW$family\fR])" 4
.IX Xref "ping_external"
.IX Item "$p->ping_external([$host, $timeout, $family])"
The "ping" method used with the external protocol.
Uses Net::Ping::External to do an external ping.
.ie n .IP "$p\->tcp_connect([$ip, $timeout])" 4
.el .IP "\f(CW$p\fR\->tcp_connect([$ip, \f(CW$timeout\fR])" 4
.IX Xref "tcp_connect"
.IX Item "$p->tcp_connect([$ip, $timeout])"
Initiates a TCP connection, for a tcp ping.
.ie n .IP "$p\->tcp_echo([$ip, $timeout, $pingstring])" 4
.el .IP "\f(CW$p\fR\->tcp_echo([$ip, \f(CW$timeout\fR, \f(CW$pingstring\fR])" 4
.IX Xref "tcp_echo"
.IX Item "$p->tcp_echo([$ip, $timeout, $pingstring])"
Performs a TCP echo.
It writes the given string to the socket and then reads it
back.  It returns 1 on success, 0 on failure.
.ie n .IP $p\->\fBclose()\fR; 4
.el .IP \f(CW$p\fR\->\fBclose()\fR; 4
.IX Xref "close"
.IX Item "$p->close();"
Close the network connection for this ping object.  The network
connection is also closed by "undef \f(CW$p\fR".  The network connection is
automatically closed if the ping object goes out of scope (e.g. \f(CW$p\fR is
local to a subroutine and you leave the subroutine).
.ie n .IP $p\->port_number([$port_number]) 4
.el .IP \f(CW$p\fR\->port_number([$port_number]) 4
.IX Xref "port_number"
.IX Item "$p->port_number([$port_number])"
When called with a port number, the port number used to ping is set to
\&\f(CW$port_number\fR rather than using the echo port.  It also has the effect
of calling \f(CW\*(C`$p\->service_check(1)\*(C'\fR causing a ping to return a successful
response only if that specific port is accessible.  This function returns
the value of the port that "ping" will connect to.
.ie n .IP $p\->mselect 4
.el .IP \f(CW$p\fR\->mselect 4
.IX Xref "mselect"
.IX Item "$p->mselect"
A \f(CWselect()\fR wrapper that compensates for platform
peculiarities.
.ie n .IP $p\->ntop 4
.el .IP \f(CW$p\fR\->ntop 4
.IX Xref "ntop"
.IX Item "$p->ntop"
Platform abstraction over \f(CWinet_ntop()\fR
.ie n .IP $p\->checksum($msg) 4
.el .IP \f(CW$p\fR\->checksum($msg) 4
.IX Xref "checksum"
.IX Item "$p->checksum($msg)"
Do a checksum on the message.  Basically sum all of
the short words and fold the high order bits into the low order bits.
.ie n .IP $p\->icmp_result 4
.el .IP \f(CW$p\fR\->icmp_result 4
.IX Xref "icmp_result"
.IX Item "$p->icmp_result"
Returns a list of addr, type, subcode.
.ie n .IP "pingecho($host [, $timeout]);" 4
.el .IP "pingecho($host [, \f(CW$timeout\fR]);" 4
.IX Xref "pingecho"
.IX Item "pingecho($host [, $timeout]);"
To provide backward compatibility with the previous version of
Net::Ping, a \f(CWpingecho()\fR subroutine is available with the same
functionality as before.  \f(CWpingecho()\fR uses the tcp protocol.  The
return values and parameters are the same as described for the "ping"
method.  This subroutine is obsolete and may be removed in a future
version of Net::Ping.
.IP "wakeonlan($mac, [$host, [$port]])" 4
.IX Xref "wakeonlan"
.IX Item "wakeonlan($mac, [$host, [$port]])"
Emit the popular wake-on-lan magic udp packet to wake up a local
device.  See also Net::Wake, but this has the mac address as 1st arg.
\&\f(CW$host\fR should be the local gateway. Without it will broadcast.
.Sp
Default host: '255.255.255.255'
Default port: 9
.Sp
.Vb 1
\&  perl \-MNet::Ping=wakeonlan \-e\*(Aqwakeonlan "e0:69:95:35:68:d2"\*(Aq
.Ve
.SH NOTES
.IX Header "NOTES"
There will be less network overhead (and some efficiency in your
program) if you specify either the udp or the icmp protocol.  The tcp
protocol will generate 2.5 times or more traffic for each ping than
either udp or icmp.  If many hosts are pinged frequently, you may wish
to implement a small wait (e.g. 25ms or more) between each ping to
avoid flooding your network with packets.
.PP
The icmp and icmpv6 protocols requires that the program be run as root
or that it be setuid to root.  The other protocols do not require
special privileges, but not all network devices implement tcp or udp
echo.
.PP
Local hosts should normally respond to pings within milliseconds.
However, on a very congested network it may take up to 3 seconds or
longer to receive an echo packet from the remote host.  If the timeout
is set too low under these conditions, it will appear that the remote
host is not reachable (which is almost the truth).
.PP
Reachability doesn't necessarily mean that the remote host is actually
functioning beyond its ability to echo packets.  tcp is slightly better
at indicating the health of a system than icmp because it uses more
of the networking stack to respond.
.PP
Because of a lack of anything better, this module uses its own
routines to pack and unpack ICMP packets.  It would be better for a
separate module to be written which understands all of the different
kinds of ICMP packets.
.SH INSTALL
.IX Header "INSTALL"
The latest source tree is available via git:
.PP
.Vb 2
\&  git clone https://github.com/rurban/Net\-Ping.git
\&  cd Net\-Ping
.Ve
.PP
The tarball can be created as follows:
.PP
.Vb 1
\&  perl Makefile.PL ; make ; make dist
.Ve
.PP
The latest Net::Ping releases are included in cperl and perl5.
.SH BUGS
.IX Header "BUGS"
For a list of known issues, visit:
.PP
<https://rt.cpan.org/NoAuth/Bugs.html?Dist=Net\-Ping>
and
<https://github.com/rurban/Net\-Ping/issues>
.PP
To report a new bug, visit:
.PP
<https://github.com/rurban/Net\-Ping/issues>
.SH AUTHORS
.IX Header "AUTHORS"
.Vb 3
\&  Current maintainers:
\&    perl11 (for cperl, with IPv6 support and more)
\&    p5p    (for perl5)
\&
\&  Previous maintainers:
\&    bbb@cpan.org (Rob Brown)
\&    Steve Peters
\&
\&  External protocol:
\&    colinm@cpan.org (Colin McMillen)
\&
\&  Stream protocol:
\&    bronson@trestle.com (Scott Bronson)
\&
\&  Wake\-on\-lan:
\&    1999\-2003 Clinton Wong
\&
\&  Original pingecho():
\&    karrer@bernina.ethz.ch (Andreas Karrer)
\&    pmarquess@bfsec.bt.co.uk (Paul Marquess)
\&
\&  Original Net::Ping author:
\&    mose@ns.ccsn.edu (Russell Mosemann)
.Ve
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright (c) 2017\-2020, Reini Urban.  All rights reserved.
.PP
Copyright (c) 2016, cPanel Inc.  All rights reserved.
.PP
Copyright (c) 2012, Steve Peters.  All rights reserved.
.PP
Copyright (c) 2002\-2003, Rob Brown.  All rights reserved.
.PP
Copyright (c) 2001, Colin McMillen.  All rights reserved.
.PP
This program is free software; you may redistribute it and/or
modify it under the same terms as Perl itself.