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Net::Telnet - interact with TELNET port or other TCP ports |
Net::Telnet - interact with TELNET port or other TCP ports
use Net::Telnet ();
see METHODS section below
Net::Telnet allows you to make client connections to a TCP port and do network I/O, especially to a port using the TELNET protocol. Simple I/O methods such as print, get, and getline are provided. More sophisticated interactive features are provided because connecting to a TELNET port ultimately means communicating with a program designed for human interaction. These interactive features include the ability to specify a time-out and to wait for patterns to appear in the input stream, such as the prompt from a shell.
Other reasons to use this module than strictly with a TELNET port are:
Here's an example that prints who's logged-on to the remote host
sparky. In addition to a username and password, you must also know
the user's shell prompt, which for this example is bash$
use Net::Telnet ();
$t = new Net::Telnet (Timeout => 10,
Prompt => '/bash\$ $/');
$t->open("sparky");
$t->login($username, $passwd);
@lines = $t->cmd("/usr/bin/who");
print @lines;
More examples are in the EXAMPLES section below.
Usage questions should be directed to the Usenet newsgroup comp.lang.perl.modules.
Contact me, Jay Rogers <jay@rgrs.com>, if you find any bugs or have suggestions for improvement.
print() and cmd() is set to
"\n" by default, so that you don't have to append all your commands
with a newline. See output_record_separator() to change the
behavior.
login() and cmd() use the prompt setting in the
object to determine when a login or remote command is complete. The
method will fail with a time-out if you don't set the prompt
correctly.
print() and waitfor() as an alternative to
login() or cmd() when they don't do what you want.
errmode() for more
information.
prompt() and waitfor() (e.g. '/bash\$ $/'). If you're
constructing a DOS like file path, you'll need to use four backslashes
to represent one (e.g. '/c:\\\\users\\\\bill>$/i').
Of course don't forget about regexp metacharacters like ., [, or
$. You'll only need a single backslash to quote them. The anchor
metacharacters ^ and $ refer to positions in the input buffer.
"\015\012" or CR LF) is converted to "\n". In the
output stream, each occurrence of "\n" is converted to a sequence
of CR LF. See binmode() to change the behavior. TCP protocols
typically use the ASCII sequence, carriage return and line feed to
designate a newline.
alarm() function. Most notably these include
Win32 machines.
More universal support for connection time-outs will be in a later release.
If you have the IO:: libraries installed (they come standard with perl5.004 and later) then IO::Socket::INET is used as a base class, otherwise FileHandle is used.
The typical bug causes a time-out error because you've made incorrect
assumptions about what the remote side actually sends. The easiest
way to reconcile what the remote side sends with your expectations is
to use input_log() or dump_log().
dump_log() allows you to see the data being sent from the remote
side before any translation is done, while input_log() shows you
the results after translation. The translation includes converting
end of line characters and stripping and responding to TELNET protocol
commands.
Two different styles of named parameters are supported. This document only shows the IO:: style:
Net::Telnet->new(Timeout => 20);
however the dash-option style is also allowed:
Net::Telnet->new(-timeout => 20);
By default, Windows machines don't come with a TELNET service. However, third party TELNET servers can be acquired to provide access to a DOS shell. As is all too familiar, many of these servers are of inferior quality.
One particularly nasty problem is a server that sends ANSI terminal escape sequences despite being told not to. These escape sequences make your job of parsing the data much more difficult. You can sometimes avoid this with a server that prompts you for console mode. Choose no to console mode.
In the calling sequences below, square brackets [] represent optional parameters.
$obj = Net::Telnet->new([Binmode => $mode,]
[Cmd_remove_mode => $mode,]
[Dump_Log => $filename,]
[Errmode => $errmode,]
[Fhopen => $filehandle,]
[Host => $host,]
[Input_log => $file,]
[Input_record_separator => $char,]
[Option_log => $file,]
[Output_log => $file,]
[Output_record_separator => $char,]
[Port => $port,]
[Prompt => $matchop,]
[Telnetmode => $mode,]
[Timeout => $secs,]);
This is the constructor for Net::Telnet objects. A new object is
returned on success, the $errmode action is performed on failure -
see errmode(). The arguments are short-cuts to methods of the same
name.
If the $host argument is given then the object is opened by
connecting to TCP $port on $host. Also see open(). The new
object returned is given the following defaults in the absence of
corresponding named arguments:
"localhost"
23
'/[\$%#>] $/'
10
"die"
"\n"
"\n"
0, which means do newline translation
"auto".
$mode = $obj->binmode;
$prev = $obj->binmode($mode);
This method controls whether or not sequences of carriage returns and
line feeds (CR LF or more specifically "\015\012") are translated.
By default they are translated (i.e. binmode is 0).
If no argument is given, the current mode is returned.
If $mode is 1 then binmode is on and newline translation is
not done.
If $mode is 0 then binmode is off and newline translation is
done. In the input stream, each sequence of CR LF is converted to
"\n" and in the output stream, each occurrence of "\n" is
converted to a sequence of CR LF.
Note that input is always buffered. Changing binmode doesn't effect what's already been read into the buffer. Output is not buffered and changing binmode will have an immediate effect.
$ok = $obj->break;
This method sends the TELNET break character. This character is provided because it's a signal outside the USASCII character set which is currently given local meaning within many systems. It's intended to indicate that the Break Key or the Attention Key was hit.
$ref = $obj->buffer;
This method returns a scalar reference to the input buffer for $obj. Data in the input buffer is data that has been read from the remote side but has yet to be read by the user. Modifications to the input buffer are returned by a subsequent read.
$obj->buffer_empty;
This method removes all data in the input buffer for $obj.
$ok = $obj->close;
This method closes the socket, file, or pipe associated with the object.
$ok = $obj->cmd($string);
$ok = $obj->cmd(String => $string,
[Output => $ref,]
[Prompt => $match,]
[Timeout => $secs,]
[Cmd_remove_mode => $mode,]);
@output = $obj->cmd($string);
@output = $obj->cmd(String => $string,
[Output => $ref,]
[Prompt => $match,]
[Timeout => $secs,]
[Cmd_remove_mode => $mode,]);
This method sends the command $string, and reads the characters sent back by the command up until and including the matching prompt. It's assumed that the program to which you're sending is some kind of command prompting interpreter such as a shell.
In a scalar context the characters read are discarded and a boolean is
returned indicating the success or failure of sending the command
string and reading the prompt. Note that in order to return on error,
errmode() must not be set to "die".
In an array context, just the output generated by the command is returned, one line per element. In other words, all the characters in between the echoed back command string and the prompt are returned. If the command happens to return no output, an array containing one element, the null string is returned. This is so the array will indicate true in a boolean context.
Many command interpreters echo back the command sent. In most
situations, this method removes the first line returned from the
remote side (i.e. the echoed back command). See cmd_remove_mode()
for more control over this feature.
Use dump_log() to debug when this method keeps timing-out and you
don't think it should.
Consider using a combination of print() and waitfor() as an
alternative to this method when it doesn't do what you want, e.g. the
command you run prompts for input.
Optional named arguments are provided to override the current settings of prompt, timeout, and cmd_remove_mode.
The Output named argument provides an alternative method of receiving command output. If you pass a scalar reference, all the output (even if it contains multiple lines) is returned in the referenced scalar. If you pass an array or hash reference, the lines of output are returned in the referenced array or hash.
$mode = $obj->cmd_remove_mode;
$prev = $obj->cmd_remove_mode($mode);
This method controls how to deal with echoed back commands in the output returned by cmd(). Typically, when you send a command to the remote side, the first line of output returned is the command echoed back. Use this mode to remove the first line of output normally returned by cmd().
If no argument is given, the current mode is returned.
If $mode is 0 then the command output returned from cmd() has no
lines removed. If $mode is a positive integer, then the first
$mode lines of command output are stripped.
By default, $mode is set to "auto". Auto means that whether or
not the first line of command output is stripped, depends on whether
or not the remote side offered to echo. By default, Net::Telnet
always accepts an offer to echo by the remote side. You can change
the default to reject such an offer using option_accept().
$fh = $obj->dump_log;
$fh = $obj->dump_log($fh);
$fh = $obj->dump_log($filename);
This method starts or stops dump format logging of all the object's
input and output. The dump format shows the blocks read and written
in a hexadecimal and printable character format. This method is
useful when debugging, however you might want to first try
input_log() as it's more readable.
If no argument is given, the current log filehandle is returned. A null string indicates logging is off.
To stop logging, use a null string as an argument.
If an open filehandle is given, it is used for logging and returned. Otherwise, the argument is assumed to be the name of a file, the file is opened and a filehandle to it is returned.
$eof = $obj->eof;
This method indicates if end of file has been read. Because the input is buffered this isn't the same thing as $obj has closed. In other words $obj can be closed but there still can be stuff in the buffer to be read. Under this condition you can still read but you won't be able to write.
$mode = $obj->errmode;
$prev = $obj->errmode($mode);
This method gets or sets the action used when errors are encountered
using the object. The first calling sequence returns the current
error mode. The second calling sequence sets it to $mode and
returns the previous mode. Valid values for $mode are "die"
(the default), "return", a coderef, or an arrayref.
When mode is "die" and an error is encountered using the object,
then an error message is printed to standard error and the program
dies.
When mode is "return" then the method generating the error places
an error message in the object and returns the undefined value in a
scalar context and a null list in list context. The error message may
be obtained using errmsg().
When mode is a coderef, then when an error is encountered coderef is called with the error message as its first argument. Using this mode you may have your own subroutine handle errors. If coderef itself returns then the method generating the error returns undefined or a null list depending on context.
When mode is an arrayref, the first element of the array must be a coderef. Any elements that follow are the arguments to coderef. When an error is encountered, the coderef is called with its arguments. Using this mode you may have your own subroutine handle errors. If the coderef itself returns then the method generating the error returns undefined or a null list depending on context.
$msg = $obj->errmsg;
$prev = $obj->errmsg(@msgs);
The first calling sequence returns the error message associated with the object. The null string is returned if no error has been encountered yet. The second calling sequence sets the error message for the object to the concatenation of @msgs and returns the previous error message. Normally, error messages are set internally by a method when an error is encountered.
$obj->error(@msgs);
This method concatenates @msgs into a string and places it in the
object as the error message. Also see errmsg(). It then performs
the error mode. Also see errmode().
If the error mode doesn't cause the program to die then the undefined value or a null list is returned depending on context.
This method is primarily used by this class or a sub-class to perform the user requested action when an error is encountered.
$ok = $obj->fhopen($fh);
This method associates the open filehandle $fh with $obj for further I/O. Filehandle $fh must already be opened.
Suppose you want to use the features of this module to do I/O to
something other than a TCP port, for example STDIN or a filehandle
opened to read from a process. Instead of opening the object for I/O
to a TCP port by using open() or new(), call this method
instead.
$data = $obj->get([Timeout => $secs,]);
This method reads a block of data from the object and returns it along
with any buffered data. If no buffered data is available to return,
it will wait for data to read using the timeout specified in the
object. You can override that timeout using $secs. Also see
timeout(). If buffered data is available to return, it also checks
for a block of data that can be immediately read.
On eof an undefined value is returned. On time-out or other errors the error mode action is performed.
An undefined value is returned for both eof and time-out when
errmode is not set to "die". Use eof() and timed_out() to
distinguish.
$line = $obj->getline([Timeout => $secs,]);
This method reads and returns the next line of data from the object.
You can use input_record_separator() to change the notion of what
separates a line. The default is "\n".
If a line isn't immediately available, this method blocks waiting for
a line or the time-out. You can override the object's timeout for
this method using $secs. Also see timeout().
On eof an undefined value is returned. On time-out or other errors the error mode action is performed.
An undefined value is returned for both eof and time-out when
errmode is not set to "die". Use eof() and timed_out() to
distinguish.
@lines = $obj->getlines([Timeout => $secs,]);
This method reads and returns the next available lines of data from
the object. You can use input_record_separator() to change the
notion of what separates a line. The default is "\n".
If a line isn't immediately available, this method blocks waiting for
one or more lines, or time-out. You can override the object's timeout
for this method using $secs. Also see timeout().
On eof a null array is returned. On time-out or other errors, the error mode action is performed.
A null array is returned for both eof and time-out when errmode is
not set to "die". Use eof() and timed_out() to distinguish.
$host = $obj->host;
$prev = $obj->host($host);
This method designates the remote host. With no argument this method returns the current host name set in the object. With an argument it sets the current host name to $host and returns the previous host name. You may indicate the remote host using either a hostname or an IP address.
$fh = $obj->input_log;
$fh = $obj->input_log($fh);
$fh = $obj->input_log($filename);
This method starts or stops logging of input. This is useful when
debugging. Also see dump_log(). Because most command interpreters
echo back commands received, its likely all your output will also be
in this log. Note that input logging occurs after newline
translation. See binmode() for details on newline translation.
If no argument is given, the log filehandle is returned. A null string indicates logging is off.
To stop logging, use a null string as an argument.
If an open filehandle is given, it is used for logging and returned. Otherwise, the argument is assumed to be the name of a file, the file is opened for logging and a filehandle to it is returned.
$rs = $obj->input_record_separator;
$prev = $obj->input_record_separator($rs);
This method designates the line delimiter for input. It's used with
getline(), getlines(), and cmd() to determine lines in the
input.
With no argument this method returns the current input record separator set in the object. With an argument it sets the input record separator to $rs and returns the previous value.
$line = $obj->lastline;
$prev = $obj->lastline($line);
This method saves the last line read from the object. This may be a useful error message when the remote side abnormally closes the connection. Typically the remote side will print an error message before closing.
With no argument this method returns the last line read from the object. With an argument it sets the last line read to $line and returns the previous value. Normally, only internal methods set the last line.
$ok = $obj->login($username, $password);
$ok = $obj->login(Name => $username,
Password => $password,
[Prompt => $match,]
[Timeout => $secs,]);
This method performs a standard login by waiting for a login prompt and responding with $username, then waiting for the password prompt and responding with $password, and then waiting for the command interpreter prompt. If any of those prompts sent by the remote side don't match what's expected, this method will time-out - unless timeout is turned off.
Login prompts must match either of the case insensitive patterns:
/login[: ]*$/i
/username[: ]*$/i
Password prompts must match the case insensitive pattern:
/password[: ]*$/i
The command interpreter prompt must match the current setting of prompt.
Use dump_log() to debug when this method keeps timing-out and you
don't think it should.
Consider using a combination of print() and waitfor() as an
alternative to this method when it doesn't do what you want, e.g. the
remote host doesn't send a username prompt.
Optional named arguments are provided to override the current settings of prompt and timeout.
$len = $obj->max_buffer_length;
$prev = $obj->max_buffer_length($len);
This method designates the maximum size of the input buffer. An error
is generated when a read causes the buffer to exceed this limit. The
default value is 1,048,576 bytes (1MB). The input buffer can grow
much larger than the block size when you continuously read using
getline() or waitfor() and the data stream contains no newlines
or matching waitfor patterns.
With no argument this method returns the current maximum buffer length set in the object. With an argument it sets the maximum buffer length to $len and returns the previous value.
$ok = $obj->open($host);
$ok = $obj->open([Host => $host,]
[Port => $port,]
[Timeout => $secs,]);
This method opens a TCP connection to $port on $host. If either
argument is missing then the current value of host() or port()
is used. An optional named argument is provided to override the
current setting of timeout.
On time-out or other connection errors, the error mode action is performed.
Time-outs don't work for this method on machines that don't implement SIGALRM - most notably Win32 machines. For those machines, an error is returned when the system reaches its own time-out while trying to connect.
A side effect of this method is to reset the alarm interval associated with SIGALRM.
$fh = $obj->option_accept([Do => $telopt,]
[Dont => $telopt,]
[Will => $telopt,]
[Wont => $telopt,]);
This method is used to indicate whether to accept or reject an offer
to enable a TELNET option made by the remote side. If you're using
Do or Will to indicate a willingness to enable, then a
notification callback must have already been defined by a prior call
to option_callback(). See option_callback() for details on
receiving enable/disable notification of a TELNET option.
You can give multiple Do, Dont, Will, or Wont arguments for different TELNET options in the same call to this method.
The following example describes the meaning of the named arguments. A
TELNET option, such as TELOPT_ECHO used below, is an integer
constant that you can import from Net::Telnet. See the source in file
Telnet.pm for the complete list.
TELOPT_ECHO
TELOPT_ECHO
TELOPT_ECHO
TELOPT_ECHO
option_send() to send a request to the remote side to enable or
disable a particular TELNET option.
$coderef = $obj->option_callback;
$prev = $obj->option_callback($coderef);
This method defines the callback subroutine that's called when a TELNET option is enabled or disabled. Once defined, the option_callback may not be undefined. However, calling this method with a different $coderef changes it.
Here are the circumstances that invoke $coderef:
option_accept() had been used to arrange that it be accepted.
option_send() was used to send a request to enable or disable an
option and the response from the remote side has just been received.
Note, that if a request to enable is rejected then $coderef is
still invoked even though the option didn't change.
&$coderef($obj, $option, $is_remote,
$is_enabled, $was_enabled, $buf_position);
buffer()
to access the object's input buffer.
$fh = $obj->option_log;
$fh = $obj->option_log($fh);
$fh = $obj->option_log($filename);
This method starts or stops logging of all TELNET options being sent
or received. This is useful for debugging when you send options via
option_send() or you arrange to accept option requests from the
remote side via option_accept(). Also see dump_log().
If no argument is given, the log filehandle is returned. A null string indicates logging is off.
To stop logging, use a null string as an argument.
If an open filehandle is given, it is used for logging and returned. Otherwise, the argument is assumed to be the name of a file, the file is opened for logging and a filehandle to it is returned.
$ok = $obj->option_send([Do => $telopt,]
[Dont => $telopt,]
[Will => $telopt,]
[Wont => $telopt,]
[Async => $boolean,]);
This method is not yet implemented. Look for it in a future version.
$hashref = $obj->option_state($telopt);
This method returns a hashref containing a copy of the current state of TELNET option $telopt.
Here are the values returned in the hash:
$ofs = $obj->output_field_separator;
$prev = $obj->output_field_separator($ofs);
This method designates the output field separator for print().
Ordinarily the print method simply prints out the comma separated
fields you specify. Set this to specify what's printed between
fields.
With no argument this method returns the current output field separator set in the object. With an argument it sets the output field separator to $ofs and returns the previous value.
$fh = $obj->output_log;
$fh = $obj->output_log($fh);
$fh = $obj->output_log($filename);
This method starts or stops logging of output. This is useful when
debugging. Also see dump_log(). Because most command interpreters
echo back commands received, its likely all your output would also be
in an input log. See input_log(). Note that output logging occurs
before newline translation. See binmode() for details on newline
translation.
If no argument is given, the log filehandle is returned. A null string indicates logging is off.
To stop logging, use a null string as an argument.
If an open filehandle is given, it is used for logging and returned. Otherwise, the argument is assumed to be the name of a file, the file is opened for logging and a filehandle to it is returned.
$ors = $obj->output_record_separator;
$prev = $obj->output_record_separator($ors);
This method designates the output record separator for print().
Ordinarily the print operator simply prints out the comma separated
fields you specify, with no trailing newline or record separator
assumed. Set this variable to specify what's printed at the end of
the print.
Note: the output record separator is set to "\n" by default, so
there's no need to append all your commands with a newline.
With no argument this method returns the current output record separator set in the object. With an argument it sets the output record separator to $ors and returns the previous value.
$port = $obj->port;
$prev = $obj->port($port);
This method designates the remote TCP port. With no argument this
method returns the current port number. With an argument it sets the
current port number to $port and returns the previous port. If
$port is a service name, then first it's converted to a port number
using the perl function getservbyname().
$ok = $obj->print(@list);
This method prints a string or a comma-separated list of strings to the opened object and returns non-zero if all data was successfully written.
By default, the output_record_separator() is set to "\n" in order
to have your commands automatically end with a newline. In most cases
your output is being read by a command interpreter which won't accept
a command until newline is read. This is similar to someone typing a
command and hitting the return key.
On failure, it's possible that some data was written. If you choose
to try and recover from a print timing-out, use print_length() to
determine how much was written before time-out occurred.
$num = $obj->print_length;
This returns the number of bytes successfully written by the most
recent print().
$matchop = $obj->prompt;
$prev = $obj->prompt($matchop);
This method sets the pattern used to find a prompt in the input
stream. It must be a string representing a valid perl pattern match
operator. The methods login() and cmd() try to read until
matching the prompt. They will fail with a time-out error if the
pattern you've chosen doesn't match what the remote side sends.
With no argument this method returns the prompt set in the object. With an argument it sets the prompt to $matchop and returns the previous value.
The default prompt is '/[\$%#>] $/'
Always use single quotes, instead of double quotes, to construct
$matchop (e.g. '/bash\$ $/'). If you're constructing a DOS like
file path, you'll need to use four backslashes to represent one
(e.g. '/c:\\\\users\\\\bill>$/i').
Of course don't forget about regexp metacharacters like ., [, or
$. You'll only need a single backslash to quote them. The anchor
metacharacters ^ and $ refer to positions in the input buffer.
$mode = $obj->telnetmode;
$prev = $obj->telnetmode($mode);
This method controls whether or not TELNET commands in the data stream are recognized and handled. The TELNET protocol uses certain character sequences sent in the data stream to control the session. If the port you're connecting to isn't using the TELNET protocol, then you should turn this mode off. The default is on.
If no argument is given, the current mode is returned.
If $mode is 0 then telnet mode is off. If $mode is 1 then
telnet mode is on.
$boolean = $obj->timed_out;
$prev = $obj->timed_out($boolean);
This method indicates if a previous read or write method timed-out.
With no argument this method returns true if a previous method timed-out. With an argument it sets the indicator. Normally, only internal methods set this indicator.
$secs = $obj->timeout;
$prev = $obj->timeout($secs);
This method sets the timeout interval that's used when performing I/O or connecting to a port. When a method doesn't complete within the timeout interval then it's an error and the error mode action is performed.
The timeout may be expressed as a relative or absolute value. If
$secs is greater than or equal to the time the program was started,
as determined by $^T, then it's the absolute time when time-out
occurs. Also see the perl function time(). A relative time-out
happens $secs from when the I/O method begins.
If $secs is 0 then time-out occurs if the data cannot be
immediately read or written. Use the undefined value to turn off
timing-out.
With no argument this method returns the timeout set in the object. With an argument it sets the timeout to $secs and returns the previous value.
$ok = $obj->waitfor($matchop);
$ok = $obj->waitfor([Match => $matchop,]
[String => $string,]
[Timeout => $secs,]);
($prematch, $match) = $obj->waitfor($matchop);
($prematch, $match) = $obj->waitfor([Match => $matchop,]
[String => $string,]
[Timeout => $secs,]);
This method reads until a pattern match or string is found in the input stream. All the characters before and including the match are removed from the input stream. On time-out, eof, or other errors the error mode action is performed.
In an array context the characters before the match and the matched characters are returned in $prematch and $match.
You can specify more than one pattern or string by simply providing multiple Match and/or String named arguments. A $matchop must be a string representing a valid Perl pattern match operator. The $string is just a substring to find in the input stream.
Use dump_log() to debug when this method keeps timing-out and you
don't think it should.
An optional named argument is provided to override the current setting of timeout.
To avoid unexpected backslash interpretation, always use single quotes
instead of double quotes to construct a match operator argument for
prompt() and waitfor() (e.g. '/bash\$ $/'). If you're
constructing a DOS like file path, you'll need to use four backslashes
to represent one (e.g. '/c:\\\\users\\\\bill>$/i').
Of course don't forget about regexp metacharacters like ., [, or
$. You'll only need a single backslash to quote them. The anchor
metacharacters ^ and $ refer to positions in the input buffer.
This example gets the current weather forecast for Brainerd, Minnesota.
my ($forecast, $t);
use Net::Telnet ();
$t = new Net::Telnet;
$t->open("rainmaker.wunderground.com");
## Wait for first prompt and "hit return".
$t->waitfor('/continue:.*$/');
$t->print("");
## Wait for second prompt and respond with city code.
$t->waitfor('/city code.*$/');
$t->print("BRD");
## Read and print the first page of forecast.
($forecast) = $t->waitfor('/[ \t]+press return to continue/i');
print $forecast;
exit;
This example checks a POP server to see if you have mail.
my ($hostname, $line, $passwd, $pop, $username);
$hostname = "your_destination_host_here";
$username = "your_username_here";
$passwd = "your_password_here";
use Net::Telnet ();
$pop = new Net::Telnet (Telnetmode => 0);
$pop->open(Host => $hostname,
Port => 110);
## Read connection message.
$line = $pop->getline;
die $line unless $line =~ /^\+OK/;
## Send user name.
$pop->print("user $username");
$line = $pop->getline;
die $line unless $line =~ /^\+OK/;
## Send password.
$pop->print("pass $passwd");
$line = $pop->getline;
die $line unless $line =~ /^\+OK/;
## Request status of messages.
$pop->print("list");
$line = $pop->getline;
print $line;
exit;
Here's an example you can use to down load a file of any type. The file is read from the remote host's standard output using cat. To prevent any output processing, the remote host's standard output is put in raw mode using the Bourne shell. The Bourne shell is used because some shells, notably tcsh, prevent changing tty modes. Upon completion, FTP style statistics are printed to stderr.
my ($block, $filename, $host, $hostname, $k_per_sec, $line,
$num_read, $passwd, $prevblock, $prompt, $size, $size_bsd,
$size_sysv, $start_time, $total_time, $username);
$hostname = "your_destination_host_here";
$username = "your_username_here";
$passwd = "your_password_here";
$filename = "your_download_file_here";
## Connect and login.
use Net::Telnet ();
$host = new Net::Telnet (Timeout => 30,
Prompt => '/[%#>] $/');
$host->open($hostname);
$host->login($username, $passwd);
## Make sure prompt won't match anything in send data.
$prompt = '_funkyPrompt_';
$host->prompt("/$prompt\$/");
$host->cmd("set prompt = '$prompt'");
## Get size of file.
($line) = $host->cmd("/bin/ls -l $filename");
($size_bsd, $size_sysv) = (split ' ', $line)[3,4];
if ($size_sysv =~ /^\d+$/) {
$size = $size_sysv;
}
elsif ($size_bsd =~ /^\d+$/) {
$size = $size_bsd;
}
else {
die "$filename: no such file on $hostname";
}
## Start sending the file.
binmode STDOUT;
$host->binmode(1);
$host->print("/bin/sh -c 'stty raw; cat $filename'");
$host->getline; # discard echoed back line
## Read file a block at a time.
$num_read = 0;
$prevblock = '';
$start_time = time;
while (($block = $host->get) and ($block !~ /$prompt$/o)) {
if (length $block >= length $prompt) {
print $prevblock;
$num_read += length $prevblock;
$prevblock = $block;
}
else {
$prevblock .= $block;
}
}
$host->close;
## Print last block without trailing prompt.
$prevblock .= $block;
$prevblock =~ s/$prompt$//;
print $prevblock;
$num_read += length $prevblock;
die "error: expected size $size, received size $num_read\n"
unless $num_read == $size;
## Print totals.
$total_time = (time - $start_time) || 1;
$k_per_sec = ($size / 1024) / $total_time;
$k_per_sec = sprintf "%3.1f", $k_per_sec;
warn("$num_read bytes received in $total_time seconds ",
"($k_per_sec Kbytes/s)\n");
exit;
Jay Rogers <jay@rgrs.com>
Copyright 1997, 2000 by Jay Rogers. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
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Net::Telnet - interact with TELNET port or other TCP ports |