FCL/sftools/dev/build: comparison releasing/cbrtools/perl/Net/libnetFAQ.pod

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+# Copyright (c) 1997 Graham Barr.
+# All rights reserved.
+=head1 NAME
+libnetFAQ - libnet Frequently Asked Questions
+=head1 DESCRIPTION
+=head2 Where to get this document
+This document is distributed with the libnet distribution, and is also
+available on the libnet web page at
+http://search.cpan.org/~gbarr/libnet/
+=head2 How to contribute to this document
+You may mail corrections, additions, and suggestions to me
+gbarr@pobox.com.
+=head1 Author and Copyright Information
+Copyright (c) 1997-1998 Graham Barr. All rights reserved.
+This document is free; you can redistribute it and/or modify it
+under the terms of the Artistic License.
+=head2 Disclaimer
+This information is offered in good faith and in the hope that it may
+be of use, but is not guaranteed to be correct, up to date, or suitable
+for any particular purpose whatsoever.  The authors accept no liability
+in respect of this information or its use.
+=head1 Obtaining and installing libnet
+=head2 What is libnet ?
+libnet is a collection of perl5 modules which all related to network
+programming. The majority of the modules available provided the
+client side of popular server-client protocols that are used in
+the internet community.
+=head2 Which version of perl do I need ?
+libnet has been know to work with versions of perl from 5.002 onwards. However
+if your release of perl is prior to perl5.004 then you will need to
+obtain and install the IO distribution from CPAN. If you have perl5.004
+or later then you will have the IO modules in your installation already,
+but CPAN may contain updates.
+=head2 What other modules do I need ?
+The only modules you will need installed are the modules from the IO
+distribution. If you have perl5.004 or later you will already have
+these modules.
+=head2 What machines support libnet ?
+libnet itself is an entirely perl-code distribution so it should work
+on any machine that perl runs on. However IO may not work
+with some machines and earlier releases of perl. But this
+should not be the case with perl version 5.004 or later.
+=head2 Where can I get the latest libnet release
+The latest libnet release is always on CPAN, you will find it
+in
+http://www.cpan.org/modules/by-module/Net/
+The latest release and information is also available on the libnet web page
+at
+http://search.cpan.org/~gbarr/libnet/
+=head1 Using Net::FTP
+=head2 How do I download files from an FTP server ?
+An example taken from an article posted to comp.lang.perl.misc
+#!/your/path/to/perl
+# a module making life easier
+use Net::FTP;
+# for debuging: $ftp = Net::FTP->new('site','Debug',10);
+# open a connection and log in!
+$ftp = Net::FTP->new('target_site.somewhere.xxx');
+$ftp->login('username','password');
+# set transfer mode to binary
+$ftp->binary();
+# change the directory on the ftp site
+$ftp->cwd('/some/path/to/somewhere/');
+foreach $name ('file1', 'file2', 'file3') {
+# get's arguments are in the following order:
+# ftp server's filename
+# filename to save the transfer to on the local machine
+# can be simply used as get($name) if you want the same name
+$ftp->get($name,$name);
+}
+# ftp done!
+$ftp->quit;
+=head2 How do I transfer files in binary mode ?
+To transfer files without <LF><CR> translation Net::FTP provides
+the C<binary> method
+$ftp->binary;
+=head2 How can I get the size of a file on a remote FTP server ?
+=head2 How can I get the modification time of a file on a remote FTP server ?
+=head2 How can I change the permissions of a file on a remote server ?
+The FTP protocol does not have a command for changing the permissions
+of a file on the remote server. But some ftp servers may allow a chmod
+command to be issued via a SITE command, eg
+$ftp->quot('site chmod 0777',$filename);
+But this is not guaranteed to work.
+=head2 Can I do a reget operation like the ftp command ?
+=head2 How do I get a directory listing from an FTP server ?
+=head2 Changing directory to "" does not fail ?
+Passing an argument of "" to ->cwd() has the same affect of calling ->cwd()
+without any arguments. Turn on Debug (I<See below>) and you will see what is
+happening
+$ftp = Net::FTP->new($host, Debug => 1);
+$ftp->login;
+$ftp->cwd("");
+gives
+Net::FTP=GLOB(0x82196d8)>>> CWD /
+Net::FTP=GLOB(0x82196d8)<<< 250 CWD command successful.
+=head2 I am behind a SOCKS firewall, but the Firewall option does not work ?
+The Firewall option is only for support of one type of firewall. The type
+supported is an ftp proxy.
+To use Net::FTP, or any other module in the libnet distribution,
+through a SOCKS firewall you must create a socks-ified perl executable
+by compiling perl with the socks library.
+=head2 I am behind an FTP proxy firewall, but cannot access machines outside ?
+Net::FTP implements the most popular ftp proxy firewall approach. The scheme
+implemented is that where you log in to the firewall with C<user@hostname>
+I have heard of one other type of firewall which requires a login to the
+firewall with an account, then a second login with C<user@hostname>. You can
+still use Net::FTP to traverse these firewalls, but a more manual approach
+must be taken, eg
+$ftp = Net::FTP->new($firewall) or die $@;
+$ftp->login($firewall_user, $firewall_passwd) or die $ftp->message;
+$ftp->login($ext_user . '@' . $ext_host, $ext_passwd) or die $ftp->message.
+=head2 My ftp proxy firewall does not listen on port 21
+FTP servers usually listen on the same port number, port 21, as any other
+FTP server. But there is no reason why this has to be the case.
+If you pass a port number to Net::FTP then it assumes this is the port
+number of the final destination. By default Net::FTP will always try
+to connect to the firewall on port 21.
+Net::FTP uses IO::Socket to open the connection and IO::Socket allows
+the port number to be specified as part of the hostname. So this problem
+can be resolved by either passing a Firewall option like C<"hostname:1234">
+or by setting the C<ftp_firewall> option in Net::Config to be a string
+in in the same form.
+=head2 Is it possible to change the file permissions of a file on an FTP server ?
+The answer to this is "maybe". The FTP protocol does not specify a command to change
+file permissions on a remote host. However many servers do allow you to run the
+chmod command via the C<SITE> command. This can be done with
+$ftp->site('chmod','0775',$file);
+=head2 I have seen scripts call a method message, but cannot find it documented ?
+Net::FTP, like several other packages in libnet, inherits from Net::Cmd, so
+all the methods described in Net::Cmd are also available on Net::FTP
+objects.
+=head2 Why does Net::FTP not implement mput and mget methods
+The quick answer is because they are easy to implement yourself. The long
+answer is that to write these in such a way that multiple platforms are
+supported correctly would just require too much code. Below are
+some examples how you can implement these yourself.
+sub mput {
+my($ftp,$pattern) = @_;
+foreach my $file (glob($pattern)) {
+$ftp->put($file) or warn $ftp->message;
+}
+}
+sub mget {
+my($ftp,$pattern) = @_;
+foreach my $file ($ftp->ls($pattern)) {
+$ftp->get($file) or warn $ftp->message;
+}
+}
+=head1 Using Net::SMTP
+=head2 Why can't the part of an Email address after the @ be used as the hostname ?
+The part of an Email address which follows the @ is not necessarily a hostname,
+it is a mail domain. To find the name of a host to connect for a mail domain
+you need to do a DNS MX lookup
+=head2 Why does Net::SMTP not do DNS MX lookups ?
+Net::SMTP implements the SMTP protocol. The DNS MX lookup is not part
+of this protocol.
+=head2 The verify method always returns true ?
+Well it may seem that way, but it does not. The verify method returns true
+if the command succeeded. If you pass verify an address which the
+server would normally have to forward to another machine, the command
+will succeed with something like
+252 Couldn't verify <someone@there> but will attempt delivery anyway
+This command will fail only if you pass it an address in a domain
+the server directly delivers for, and that address does not exist.
+=head1 Debugging scripts
+=head2 How can I debug my scripts that use Net::* modules ?
+Most of the libnet client classes allow options to be passed to the
+constructor, in most cases one option is called C<Debug>. Passing
+this option with a non-zero value will turn on a protocol trace, which
+will be sent to STDERR. This trace can be useful to see what commands
+are being sent to the remote server and what responses are being
+received back.
+#!/your/path/to/perl
+use Net::FTP;
+my $ftp = new Net::FTP($host, Debug => 1);
+$ftp->login('gbarr','password');
+$ftp->quit;
+this script would output something like
+Net::FTP: Net::FTP(2.22)
+Net::FTP:   Exporter
+Net::FTP:   Net::Cmd(2.0801)
+Net::FTP:   IO::Socket::INET
+Net::FTP:     IO::Socket(1.1603)
+Net::FTP:       IO::Handle(1.1504)
+Net::FTP=GLOB(0x8152974)<<< 220 imagine FTP server (Version wu-2.4(5) Tue Jul 29 11:17:18 CDT 1997) ready.
+Net::FTP=GLOB(0x8152974)>>> user gbarr
+Net::FTP=GLOB(0x8152974)<<< 331 Password required for gbarr.
+Net::FTP=GLOB(0x8152974)>>> PASS ....
+Net::FTP=GLOB(0x8152974)<<< 230 User gbarr logged in.  Access restrictions apply.
+Net::FTP=GLOB(0x8152974)>>> QUIT
+Net::FTP=GLOB(0x8152974)<<< 221 Goodbye.
+The first few lines tell you the modules that Net::FTP uses and their versions,
+this is useful data to me when a user reports a defect. The last seven lines
+show the communication with the server. Each line has three parts. The first
+part is the object itself, this is useful for separating the output
+if you are using multiple objects. The second part is either C<<<<<> to
+show data coming from the server or C<&gt&gt&gt&gt> to show data
+going to the server. The remainder of the line is the command
+being sent or response being received.
+=head1 AUTHOR AND COPYRIGHT
+Copyright (c) 1997 Graham Barr.
+All rights reserved.
+=for html <hr>
+I<$Id: //depot/libnet/Net/libnetFAQ.pod#6 $>