Authen::Libwrap

Authen::Libwrap(3)   User Contributed Perl Documentation   Authen::Libwrap(3)



NAME
       Authen::Libwrap - access to Wietse Venema’s TCP Wrappers library

SYNOPSIS
	 use Authen::Libwrap qw( hosts_ctl STRING_UNKNOWN );

	 # we know the remote username (using identd)
	 $rc = hosts_ctl(
	   "programname",
	       "hostname.domain.com",
	       "10.1.1.1",
	       "username"
	 );
	 print "Access is ", $rc ? "granted" : "refused", "\n";

	 # we don’t know the remote username
	 $rc = hosts_ctl(
	   "programname",
	       "hostname.domain.com",
	       "10.1.1.1"),
	 );
	 print "Access is ", $rc ? "granted" : "refused", "\n";

	 # use a socket instead
	 my $client = $listener->accept();
	 $rc = hosts_ctl( "programname" $socket );
	 print "Access is ", $rc ? "granted" : "refused", "\n";

DESCRIPTION
       The Authen::Libwrap module allows you to access the hosts_ctl() func-
       tion from the popular TCP Wrappers security package.  This allows val-
       idation of network access from perl programs against the system-wide
       hosts.allow file.

       If any of the parameters to hosts_ctl() are not known (i.e. username
       due to lack of an identd server), the constant STRING_UNKNOWN may be
       passed to the function.

FUNCTIONS
       Authen::Libwrap has only one function, though it can be invoked in
       several ways.  In each case, an true return code indicates that the
       connection is allowed per the rules in hosts.allow and an undef value
       indicates the opposite.

       hosts_ctl($daemon, $hostname, $ip_addr, [ $user ] )

       Takes three mandatory and one optional argument. $daemon is the ser-
       vice for which access is being requested (like ’ftpd’ or ’sendmail’).
       $hostname is the name of the host requesting access. $ip_addr is the
       IP address of the host in dotted-quad notation. $user is the name of
       the user requesting access. If unknown, $user can be omitted;
       STRING_UNKNOWN will be passed in it’s place.

       hosts_ctl($daemon, $socket, [ $user ] )

       If you have a socket (be it a glob, glob reference or an
       IO::Socket::INET, you can pass that as the second argument. The host-
       name and IP address will be determined using this socket. If the host-
       name or IP address cannot be determined from the socket,
       STRING_UNKNOWN will be passed in their place.

DEBUGGING
       If you want to see the arguments that will be passed to the C function
       hosts_ctl(), set $Authen::Libwrap::DEBUG to a true value.

EXPORTS
       Nothing unless you ask for it.

       hosts_ctl optionally

       STRING_UNKNOWN optionally

EXPORT_TAGS
       * functions
	    hosts_ctl

       * constants
	    STRING_UNKNOWN

       * all
	   everything the module has to offer.

CONSTANTS
	STRING_UNKNOWN

BUGS
       * twist in hosts.allow
	   Calls to hosts_ctl() which match a line in hosts.allow that uses
	   the "twist" option will terminate the running perl program.	This
	   is not a bug in Authen::Libwrap per se -- libwrap uses exec(3) to
	   replace the running process with the specified program, so there’s
	   nothing to return to.

	   Some operating systems ship with a default catch-all rule in
	   hosts.allow that uses the twist option.  You may have to modify
	   this configuration to use Authen::Libwrap effectively.

       * Test suite is not comprehensive
	   The test suite isn’t very comprehensive because the path to
	   hosts.allow is set when libwrap is built and I can’t tell what the
	   user’s rules are. I can make sure the function calls don’t die,
	   but I can’t really tell if any call to hosts_ctl should give back
	   a true or false value.

TODO
       In early 2003 I was contacted by another Perl developer who had devel-
       oped an XS interface to libwrap that covered more of the API than mine
       did.  Originally he offered it as a patch to my module, but at the
       time I wasn’t in a position to actively maintain anything on CPAN, so
       I suggested that he upload it himself. I unfortunately lost the email
       thread to a disk crash.

       As of December 2003 I don’t see any other modules professing to sup-
       port libwrap om CPAN. If that person is still out there, please get in
       contact with me, otherwise I’ll plan on implementing some of these
       TODOs in the new year:

       * provide support for hosts_access and request_* functions
       * develop an OO interface

SEE ALSO
       Authen::Tcpdmatch, a Pure Perl module that can parse hosts.allow and
       hosts.deny if you don’t need all the underlying features of libwrap.

       hosts_access(3), hosts_access(5), hosts_options(5)

       Wietse’s tools and papers page: <ftp://ftp.porcupine.org/pub/secu-
       rity/index.html>.

AUTHOR
       James FitzGibbon, <jfitz@CPAN.org>



perl v5.8.8			  2008-09-05		   Authen::Libwrap(3)