Net::Traceroute:PurePerl - traceroute(1) functionality in perl via raw sockets
VERSION
This document describes version 0.10 of Net::Traceroute::PurePerl.
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 perl5. 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 also be root to use the raw sockets.
INSTALLATION
Basic Installation
Net::Traceroute::PurePerl may be installed through the CPAN shell in the
usual CPAN shell manner. This typically is:
$ perl -MCPAN -e 'install Net::Traceroute::PurePerl'
You can also read this README from the CPAN shell:
$ perl -MCPAN -e shell
cpan> readme Net::Traceroute::PurePerl
And you can install the module from the CPAN prompt as well:
cpan> install Net::Traceroute::PurePerl
Manual Installation
Net::Traceroute::PurePerl can also be installed manually.
<ftp://ftp-mirror.internap.com/pub/CPAN/authors/id/A/AH/AHOYING/> or a
similarly named directory at your favorite CPAN mirror should hold the
latest version.
Downloading and unpacking the distribution are left up to the reader.
To build and test it:
perl Makefile.PL
make
make test
The test program, t/01_trace.t, makes an excellent sample program. It
was adapted from the code used to test and develop this module. There
may be additional sample programs in the examples folder.
When you are ready to install the module:
make install
It should now be ready to use.
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.
VERSION CHANGES
This version of Net::Traceroute::PurePerl is a complete rewrite of the
internal traceroute code used in the 0.02 release. As such a number of
new capabilities have been introduced, and probably a number of bugs as
well.
The public methods have remained unchanged, and this should be a drop in
replacement for the older version.
This version no longer resolves router IPs to host names in the
traceroute code. If you need the IP resolved you have to do it from your
code, or use the pretty_print method with a positive value passed as an
argument.
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.
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_hop => $first_hop,]
[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 USP packets with
incrementing ports. It defaults to udp.
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_hop - 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_hop([FIRST_HOP])
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 *N*th 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
Tom Scanlan <tscanlan@openreach.com> owner Net::Traceroute::PurePerl
Andrew Hoying <ahoying@cpan.org> current co-maintainer of
Net::Traceroute::PurePerl. Any bugs in this release are mine, please
send me the bug reports.
Daniel Hagerty <hag@ai.mit.edu> owner of Net::Traceroute and input on
this fella
COPYRIGHT
Go right ahead and copy it. 2002 Tom Scanlan. Copyright 2006 by Andrew
Hoying. Don't blame me for damages, just the bugs.
Net::Traceroute::PurePerl is free software; you may redistribute it and
or modify it under the same terms as Perl itself.