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Net-Traceroute-PurePerl-0.10_03
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NAME

Net::Traceroute::PurePerl - traceroute(1) implementation in Perl using raw sockets

SYNOPSIS

use Net::Traceroute::PurePerl;

my $t = new Net::Traceroute::PurePerl(
     backend        => 'PurePerl', # this optional
     host           => 'www.openreach.com',
     debug          => 0,
     max_ttl        => 12,
     query_timeout  => 2,
     packetlen      => 40,
     protocol       => 'udp', # Or icmp
);
$t->traceroute;
$t->pretty_print;

DESCRIPTION

This module implements traceroute(1) functionality for Perl. It allows you to trace the path IP packets take to a destination. It is implemented by using raw sockets to act just like the regular traceroute.

You must have root privileges to use the raw sockets.

OVERVIEW

A new Net::Traceroute::PurePerl object must be created with the new method. This will not perform the traceroute immediately, unlike Net::Traceroute. It will return a "template" object that can be used to set parameters for several subsequent traceroutes.

Methods are available for accessing information about a given traceroute attempt. There are also methods that view/modify the options that are passed to the object's constructor.

To trace a route, UDP or ICMP packets are sent with a small TTL (time-to-live) field in an attempt to get intervening routers to generate ICMP TIME_EXCEEDED messages.

CONSTRUCTOR

$obj = Net::Traceroute::PurePerl->new(
        [base_port        => $base_port,]
        [debug            => $debuglvl,]
        [max_ttl          => $max_ttl,]
        [host             => $host,]
        [queries          => $queries,]
        [query_timeout    => $query_timeout,]
        [source_address   => $srcaddr,]
        [packetlen        => $packetlen,]
        [concurrent_hops  => $concurrent,]
        [first_ttl        => $first_ttl,]
        [device           => $device,]
        [protocol         => $protocol,]
);

This is the constructor for a new Net::Traceroute object. If given host, it will NOT actually perform the traceroute. You MUST call the traceroute method later.

Possible options are:

host - A host to traceroute to. If you don't set this, you get a Traceroute object with no traceroute data in it. The module always uses IP addresses internally and will attempt to lookup host names via inet_aton.

base_port - Base port number to use for the UDP queries. Traceroute assumes that nothing is listening to port base_port to base_port + (nhops * nqueries - 1) where nhops is the number of hops required to reach the destination address and nqueries is the number of queries per hop. Default is what the system traceroute uses (normally 33434) Traceroute's -p option.

debuglvl - A number indicating how verbose debug information should be. Please include debug=>9 output in bug reports.

max_ttl - Maximum number of hops to try before giving up. Default is what the system traceroute uses (normally 30). Traceroute's -m option.

queries - Number of times to send a query for a given hop. Defaults to whatever the system traceroute uses (3 for most traceroutes). Traceroute's -q option.

query_timeout - How many seconds to wait for a response to each query sent. Uses the system traceroute's default value of 5 if unspecified. Traceroute's -w option.

timeout - unused here

source_address - Select the source address that traceroute will use. Traceroute's -S option.

packetlen - Length of packets to use. Traceroute tries to make the IP packet exactly this long.

trace_program - unused here

no_fragment - unused at the moment

use_alarm - unused in this version

protocol - Either ICMP or UDP. ICMP uses ICMP echo packets with incrementing sequence numbers, while UDP uses UDP packets with incrementing ports. UDP is the default.

concurrent_hops - This is the maximum number of outstanding packets sent at one time. Setting this to a high number may overflow your socket receive buffer and slightly delay the processing of response packets, making the round trip time reported slightly higher, however it will significantly decrease the amount of time it takes to run a traceroute. Defaults to 6. Traceroute's -N option.

first_ttl - This is the lowest TTL to use. Setting this will skip the first x routers in the path, especially useful if they never change. Defaults to 1. Traceroute's -f option.

device - The device to send the packet from. Normally this is determined by the system's routing table, but it can be overridden. It defaults to undef. Traceroute's -I option.

METHODS

traceroute

Run the traceroute. Will fill in the rest of the object for informational queries.

The traceroute method is a blocking call. It will not return until the max_ttl is reached or the host is reached. As such, if your program is time dependent the call should be wrapped in an eval with an ALARM set.

eval {
  local $SIG{ALRM} = sub { die "alarm" };
  alarm $timeout;
  $success = $t->traceroute();
  alarm 0;
}
warn "Traceroute timed out\n" if ($@ and $@ eq "alarm");

Returns 1 if the host was reached, or 0 if it wasn't.

Controlling traceroute invocation

Each of these methods return the current value of the option specified by the corresponding constructor option. They will set the object's instance variable to the given value if one is provided.

Changing an instance variable will only affect newly performed traceroutes. Setting a different value on a traceroute object that has already performed a trace has no effect.

See the constructor documentation for information about methods that aren't documented here.

base_port([PORT])
max_ttl([PORT])
queries([QUERIES])
query_timeout([TIMEOUT])
host([HOST])
source_address([SRC])
packetlen([LEN])
use_alarm([0|1])
protocl([PROTOCOL])
concurrent_hops([CONCURRENT])
first_ttl([FIRST_TTL])
device([DEVICE])

Obtaining information about a Trace

These methods return information about a traceroute that has already been performed.

Any of the methods in this section that return a count of something or want an Nth type count to identify something employ one based counting.

pretty_print

Prints to stdout a traceroute-like text. Tries to mimic traceroute(1)'s output as close as possible with a few exceptions. First, the columns are easier to read, and second, a new line is started if the host IP changes instead of printing the new IP inline. The first column stays the same hop number, only the host changes.

Passing in an argument of 1 will make pretty_print resolve the names of the router ips, otherwise they are printed as raw ip addresses, like Traceroute's -n option.

stat

Returns the status of a given traceroute object. One of TRACEROUTE_OK, TRACEROUTE_TIMEOUT, or TRACEROUTE_UNKNOWN (each defined as an integer). TRACEROUTE_OK will only be returned if the host was actually reachable.

found

Returns 1 if the host was found, undef otherwise.

pathmtu

If your traceroute supports MTU discovery, this method will return the MTU in some circumstances. You must set no_fragment, and must use a packetlen larger than the path mtu for this to be set.

NOTE: This doesn't work with this version.

hops

Returns the number of hops that it took to reach the host.

hop_queries(HOP)

Returns the number of queries that were sent for a given hop. This should normally be the same for every query.

hop_query_stat(HOP, QUERY)

Return the status of the given HOP's QUERY. The return status can be one of the following (each of these is actually an integer constant function defined in Net::Traceroute's export list):

QUERY can be zero, in which case the first succesful query will be returned.

TRACEROUTE_OK

Reached the host, no problems.

TRACEROUTE_TIMEOUT

This query timed out.

TRACEROUTE_UNKNOWN

Your guess is as good as mine. Shouldn't happen too often.

TRACEROUTE_UNREACH_NET

This hop returned an ICMP Network Unreachable.

TRACEROUTE_UNREACH_HOST

This hop returned an ICMP Host Unreachable.

TRACEROUTE_UNREACH_PROTO

This hop returned an ICMP Protocol unreachable.

TRACEROUTE_UNREACH_NEEDFRAG

Indicates that you can't reach this host without fragmenting your packet further. Shouldn't happen in regular use.

TRACEROUTE_UNREACH_SRCFAIL

A source routed packet was rejected for some reason. Shouldn't happen.

TRACEROUTE_UNREACH_FILTER_PROHIB

A firewall or similar device has decreed that your traffic is disallowed by administrative action. Suspect sheer, raving paranoia.

TRACEROUTE_BSDBUG

The destination machine appears to exhibit the 4.[23]BSD time exceeded bug.

hop_query_host(HOP, QUERY)

Return the dotted quad IP address of the host that responded to HOP's QUERY.

QUERY can be zero, in which case the first succesful query will be returned.

hop_query_time(HOP, QUERY)

Return the round trip time associated with the given HOP's query. If your system's traceroute supports fractional second timing, so will Net::Traceroute.

QUERY can be zero, in which case the first succesful query will be returned.

BUGS and LIMITATIONS

I have not tested the cloning functions of Net::Traceroute::PurePerl. It ought to work, but if not, BUG me.

This module requires root or administrative privileges to run. It opens a raw socket to listen for TTL exceeded messages. Take appropriate precautions.

Windows only supports ICMP traceroutes. This may change in a future release, but it is a real pain since Windows doesn't send ICMP error messages to applications for other protocols unless the socket is in promiscous mode. :(

The current version does not correctly detect network unreachable and other nonstandard ICMP errors. This can lead to problems on networks where these errors are sent instead of a port unreachable or ttl exceeded packet.

The current version does not support Net::Traceroute's clone method. Calling clone will create an object that is unusable at this point.

TODO

  • Implement IPv6 capability.

  • Implement TCP traceroute.

  • Fix bugs listed above.

SEE ALSO

traceroute(1)

This module's traceroute code was heavily influenced by Net::Ping.

See the examples folder and the test programs for more examples of this module in action.

AUTHOR

The original implementation of this module was done by Tom Scanlan with input from Daniel Hagerty. Andrew Hoying made significant changes and rewrote much of the core code. John Kristoff is the current maintainer.

COPYRIGHT

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.