NAME¶
Net::Traceroute - traceroute(1) functionality in perl
SYNOPSIS¶
use Net::Traceroute;
$tr = Net::Traceroute->new(host => "life.ai.mit.edu");
if($tr->found) {
my $hops = $tr->hops;
if($hops > 1) {
print "Router was " .
$tr->hop_query_host($tr->hops - 1, 0) . "\n";
}
}
DESCRIPTION¶
This module implements a parser for various traceroute implementations. At
present, it can parse most LBL traceroute derivatives used on typical unixes,
and the traceroute of cisco IOS. Traceroutes known not to be supported include
that of Microsoft Windows and HP-UX.
This module has two basic modes of operation, one, where it will run traceroute
for you, and the other where you provide text from previously runing
traceroute to parse.
OVERVIEW¶
A new Net::Traceroute object must be created with the
new method.
Depending on exactly how the constructor is invoked, it may perform some
tracing and/or parsing actions immediately, or it may 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 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 AND CLONING¶
$obj = Net::Traceroute->new([base_port => $base_port,]
[debug => $debuglvl,]
[max_ttl => $max_ttl,]
[host => $host,]
[text => $text,]
[queries => $queries,]
[query_timeout => $query_timeout,]
[timeout => $timeout,]
[source_address => $srcaddr,]
[tos => $tos,]
[packetlen => $packetlen,]
[trace_program => $program,]
[no_fragment => $nofrag,]
[use_icmp => $useicmp,]
[use_tcp => $usetcp,]
);
$frob = $obj->clone([options]);
This is the constructor for a new Net::Traceroute object. If given
"host", it will immediately perform the traceroute. If given
"text", it will parse that text as traceroute output.
Given an existing Net::Traceroute object $obj as a template, you can call
$obj->
clone() with the usual constructor parameters. The same rules
apply about defining host; that is, traceroute will be run if it is defined,
or text will be parsed. You can always pass "host =" undef, text
=> undef> to clone.
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.
text - Output from a previously run traceroute. If set, and host isn't,
the given text will be parsed.
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 - 1)" where nhops is the number of hops required
to reach the destination address. 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 - Maximum time, in seconds, to wait for the traceroute to
complete. If not specified, the traceroute will not return until the host has
been reached, or traceroute counts to infinity ("max_ttl" *
"queries" * "query_timeout"). Note that this option is
implemented by Net::Traceroute, not the underlying traceroute command.
source_address - Select the source address that traceroute wil use.
tos - Specify a ToS value for traceroute to use.
packetlen - Length of packets to use. Traceroute tries to make the IP
packet exactly this long.
trace_program - Name of the traceroute program. Defaults to traceroute.
You can pass traceroute6 to do IPv6 traceroutes.
no_fragment - Set the IP don't fragment bit. Some traceroute programs
will perform path mtu discovery with this option.
use_icmp - Request that traceroute perform probes with ICMP echo packets,
rather than UDP.
use_tcp - Request that traceoute perform probes with TCP SYNs.
METHODS¶
- traceroute
- Run system traceroute, and parse the results. Will fill in the rest of the
object for informational queries.
- parse
- Parse the previously provided "text", filling in the rest of the
object for queries.
- argv
- Returns a list of arguments that traceroute will be invoked with. For
debugging and/or overriding by subclasses.
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])
- text([TEXT])
- timeout([TIMEOUT])
- source_address([SRC])
- packetlen([LEN])
- trace_program([PROGRAM])
- no_fragment([PROGRAM])
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.
- 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
- Attempt to return 1 if the host was found, undef otherwise. This test is a
poor heuristic, and will frequently give wrong answers.
- 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.
- 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 successful 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_PORT
- Use in cisco and traceroute6 parsing. In cisco, "!U", in
traceroute6, a "!".
- TRACEROUTE_UNREACH_ADDR
- This hop returned an ICMP6 address 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.
- TRACEROUTE_SOURCE_QUENCH
- Some machine has generated an ICMP Source Quench message, asking you to
slow down.
- TRACEROUTE_INTERRUPTED
- "User interrupted test". Cisco's traceroute does this. Its
unclear how to produce it.
- 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 successful 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 successful query will be
returned.
CLONING SUPPORT BEFORE 1.04¶
Net::Traceroute Versions before 1.04 used new to clone objects. This has been
deprecated in favor of the
clone() method.
If you have code of the form:
my $template = Net::Traceroute->new();
my $tr = $template->new(host => "localhost");
You need to change the $template->new to $template->clone.
This behavior was changed because it interfered with subclassing.
BUGS¶
Net::Traceroute parses the output of the system traceroute command. As such, it
may not work on your system. Support for more traceroute outputs (e.g.
Windows, HPUX) could be done, although currently the code assumes there is
"One true traceroute".
The actual functionality of traceroute could also be implemented natively in
perl or linked in from a C library.
Versions prior to 1.04 had some interface issues for subclassing. These issues
have been addressed, but required a public interface change. If you were
relying on the behavior of new to clone existing objects, your code needs to
be fixed.
SEE ALSO¶
traceroute(1)
AUTHOR¶
Daniel Hagerty <hag@ai.mit.edu>
COPYRIGHT¶
Copyright 1998, 1999 Massachusetts Institute of Technology Copyright 2000, 2001
Daniel Hagerty
Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that the
above copyright notice appear in all copies and that both that copyright
notice and this permission notice appear in supporting documentation, and that
the name of M.I.T. not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior permission.
M.I.T. makes no representations about the suitability of this software for any
purpose. It is provided "as is" without express or implied
warranty.