NAME¶
Net::Telnet::Cisco - interact with a Cisco router
SYNOPSIS¶
use Net::Telnet::Cisco;
my $session = Net::Telnet::Cisco->new(Host => '123.123.123.123');
$session->login('login', 'password');
# Execute a command
my @output = $session->cmd('show version');
print @output;
# Enable mode
if ($session->enable("enable_password") ) {
@output = $session->cmd('show privilege');
print "My privileges: @output\n";
} else {
warn "Can't enable: " . $session->errmsg;
}
$session->close;
DESCRIPTION¶
Net::Telnet::Cisco provides additional functionality to Net::Telnet for dealing
with Cisco routers.
cmd() parses router-generated error messages - the kind that begin with a
'%' - and stows them in $obj->
errmsg(), so that errmode can be used
to perform automatic error-handling actions.
CAVEATS¶
Before you use Net::Telnet::Cisco, you should have a good understanding of
Net::Telnet, so read it's documentation first, and then come back here to see
the improvements.
Some things are easier to accomplish with UCD's C-based SNMP module, or the
all-perl Net::SNMP. SNMP has three advantages: it's faster, handles errors
better, and doesn't use any VTYs on the router. SNMP does have some
limitations, so for anything you can't accomplish with SNMP, there's
Net::Telnet::Cisco.
METHODS¶
- new - create new Net::Telnet::Cisco object
-
$session = Net::Telnet::Cisco->new(
[Autopage => $boolean,] # 1
[More_prompt => $matchop,] # '/(?m:^[\s\0]*--More--)/',
[Always_waitfor_prompt => $boolean,] # 1
[Waitfor_pause => $milliseconds,] # 0.1
[Normalize_cmd => $boolean,] # 1
[Send_wakeup => $when,] # 0
[Ignore_warnings => $boolean,] # 0
[Warnings => $matchop,] # see docs
[Errors => $matchop,] # see docs
# Net::Telnet arguments
[Binmode => $mode,]
[Cmd_remove_mode => $mode,]
[Dump_Log => $filename,]
[Errmode => $errmode,]
[Fhopen => $filehandle,]
[Host => $host,]
[Input_log = => $file,]
[Input_record_separator => $chars,]
[Option_log => $file,]
[Ors = => $chars,]
[Output_log => $file,]
[Output_record_separator => $chars,]
[Port => $port,]
[Prompt = => $matchop,] # see docs
[Rs => $chars,]
[Telnetmode => $mode,]
[Timeout => $secs,]);
);
Creates a new object. Read `perldoc perlboot` if you don't understand
that.
- login - login to a router
-
$ok = $obj->login($username, $password);
$ok = $obj->login([Name => $username,]
[Password => $password,]
[Passcode => $passcode,] # for Secur-ID/XTACACS
[Prompt => $match,]
[Timeout => $secs,]);
All arguments are optional as of v1.05. Some routers don't ask for a
username, they start the login conversation with a password request.
- cmd - send a command
-
$ok = $obj->cmd($string);
$ok = $obj->cmd(String => $string,
[Output => $ref,]
[Cmd_remove_mode => $mode,]
[Errmode => $mode,]
[Input_record_separator => $chars,]
[Ors => $chars,]
[Output_record_separator => $chars,]
[Prompt => $match,]
[Rs => $chars,]
[Timeout => $secs,]);
@output = $obj->cmd($string);
@output = $obj->cmd(String => $string,
[Output => $ref,]
[Cmd_remove_mode => $mode,]
[Errmode => $mode,]
[Input_record_separator => $chars,]
[Ors => $chars,]
[Output_record_separator => $chars,]
[Prompt => $match,]
[Rs => $chars,]
[Timeout => $secs,]);
Normalize_cmd has been added to the default Net::Telnet args. It lets you
temporarily change whether backspace, delete, and kill characters are
parsed in the command output. (This is performed by default)
- prompt - return control to the program whenever this string occurs
in router output
-
$matchop = $obj->prompt;
$prev = $obj->prompt($matchop);
The default cmd_prompt changed in v1.05. It's suitable for matching prompts
like "router$ ", "router# ", "router> (enable)
", and "router(config-if)# "
Let's take a closer look, shall we?
(?m: # Net::Telnet doesn't accept quoted regexen (i.e. qr//)
# so we need to use an embedded pattern-match modifier
# to treat the input as a multiline buffer.
^ # beginning of line
\r? # optional linefeed
[\w.-]+ # router hostname
\s? # optional space
(?: # Strings like "(config)" and "(config-if)", "(config-line)",
# and "(config-router)" indicate that we're in privileged
\(config[^\)]*\) # EXEC mode (i.e. we're enabled).
)? # The middle backslash is only there to appear my syntax
# highlighter.
\s? # more optional space
[\$#>] # Prompts typically end with "$", "#", or ">". Backslash
# for syntax-highlighter.
\s? # more space padding
(?: # Catalyst switches print "(enable)" when in privileged
\(enable\) # EXEC mode.
)?
\s* # spaces before the end-of-line aren't important to us.
$ # end of line
) # end of (?m:
The default prompt published in 1.03 was
"/^\s*[\w().-]*[\$#>]\s?(?:\(enable\))?\s*$/". As you can
see, the prompt was drastically overhauled in 1.05. If your code suddenly
starts timing out after upgrading Net::Telnet::Cisco, this is the first
thing to investigate.
- enable - enter enabled mode
-
$ok = $obj->enable;
$ok = $obj->enable($password);
$ok = $obj->enable(
[Name => $name,]
[Password => $password,]
[Passcode => $passcode,]
[Level => $level,]
);
This method changes privilege level to enabled mode, (i.e. root)
If a single argument is provided by the caller, it will be used as a
password. For more control, including the ability to set the
privilege-level, you must use the named-argument scheme.
enable() returns 1 on success and undef on failure.
- is_enabled - Am I root?
-
$bool = $obj->is_enabled;
A trivial check to see whether we have a root-style prompt, with either the
word "(enable)" in it, or a trailing "#".
Warning: this method will return false positives if your prompt has
"#"s in it. You may be better off calling
"$obj->cmd("show privilege")" instead.
- disable - leave enabled mode
-
$ok = $obj->disable;
This method exits the router's privileged mode.
- ios_break - send a break (control-^)
-
$ok = $obj->ios_break( [ additional strings to print, ... ] );
You may have to use errmode(), fork, or threads to break at the an
appropriate time.
- last_prompt - displays the last prompt matched by
prompt()
-
$match = $obj->last_prompt;
last_prompt() will return '' if the program has not yet matched a
prompt.
- always_waitfor_prompt - waitfor and cmd prompt behaviour
-
$boolean = $obj->always_waitfor_prompt;
$boolean = $obj->always_waitfor_prompt($boolean);
Default value: 1
If you pass a Prompt argument to cmd() or waitfor() a String
or Match, they will return control on a successful match of your
argument(s) or the default prompt. Set always_waitfor_prompt to 0 to
return control only for your arguments.
This method has no effect on login(). login() will always wait
for a prompt.
- waitfor_pause - insert a small delay before waitfor()
-
$boolean = $obj->waitfor_pause;
$boolean = $obj->waitfor_pause($milliseconds);
Default value: 0.1
In rare circumstances, the last_prompt is set incorrectly. By adding a very
small delay before calling the parent class's waitfor(), this bug
is eliminated. If you ever find reason to modify this from it's default
setting, please let me know.
- autopage - Turn autopaging on and off
-
$boolean = $obj->autopage;
$boolean = $obj->autopage($boolean);
Default value: 1
IOS pages output by default. It expects human eyes to be reading the output,
not programs. Humans hit the spacebar to scroll page by page so
autopage() mimicks that behaviour. This is the slow way to handle
paging. See the Paging EXAMPLE for a faster way.
- normalize_cmd - Turn normalization on and off
-
$boolean = $obj->normalize_cmd;
$boolean = $obj->normalize_cmd($boolean);
Default value: 1
IOS clears '--More--' prompts with backspaces (e.g. ^H). If you're excited
by the thought of having raw control characters like ^H (backspace), ^?
(delete), and ^U (kill) in your command output, turn this feature off.
Logging is unaffected by this setting.
- more_prompt - Matchop used by autopage()
-
$matchop = $obj->prompt;
$prev = $obj->prompt($matchop);
Default value: '/(?m:^(?:[\s\0]*--More--)/',
Please email me if you find others.
- send_wakeup - send a newline to the router at login time
-
$when = $obj->send_wakeup;
$when = $obj->send_wakeup( 'connect' );
$when = $obj->send_wakeup( 'timeout' );
$when = $obj->send_wakeup( 0 );
Default value: 0
Some routers quietly allow you to connect but don't display the expected
login prompts. Sends a newline in the hopes that this spurs the routers to
print something.
'connect' sends a newline immediately upon connection. 'timeout' sends a
newline if the connection timeouts. 0 turns this feature off.
I understand this works with Livingston Portmasters.
- ignore_warnings - Don't call error() for warnings
-
$boolean = $obj->ignore_warnings;
$boolean = $obj->ignore_warnings($boolean);
Default value: 0
Not all strings that begin with a '%' are really errors. Some are just
warnings. By setting this, you are ignoring them. This will show up in the
logs, but that's it.
- warnings - Matchop used by ignore_warnings().
-
$boolean = $obj->warnings;
$boolean = $obj->warnings($matchop);
Default value:
'/(?mx:^%\s?Unknown\ VPN
|^%\s?IP\ routing\ table\ VRF.*\ does\ not\ exist\.\ Create\ first$
|^%\s?No\ CEF\ interface\ information
|^%\s?No\ matching\ route\ to\ delete$
|^%\s?Not\ all\ config\ may\ be\ removed\ and\ may\ reappear\ after\ reactivating
|^%\s?Warning:
)/',
Not all strings that begin with a '%' are really errors. Some are just
warnings. Cisco calls these the CIPMIOSWarningExpressions.
- errors - Matchop used to catch special-cased errors.
-
$boolean = $obj->errors;
$boolean = $obj->errors($matchop);
Default value:
'/(?mx:^Unknown\ command\ "[^\"]*"\ Use\ \'help\'\ for\ more\ info\.)/',
Some errors don't begin with a '%'. Trap them here.
EXAMPLES¶
Paging
v1.08 added internal autopaging support to
cmd(). Whenever a '--Page--'
prompt appears on the screen, we send a space right back. It works, but it's
slow. You'd be better off sending one of the following commands just after
login():
# To a router
$session->cmd('terminal length 0');
# To a switch
$session->cmd('set length 0');
Logging
Want to see the session transcript? Just call
input_log().
e.g.
my $session = Net::Telnet::Cisco->new(Host => $router,
Input_log => "input.log",
);
See
input_log() in Net::Telnet for info.
Input logs are easy-to-read translated transcripts with all of the control
characters and telnet escapes cleaned up. If you want to view the raw session,
see
dump_log() in Net::Telnet. If you're getting tricky and using
print() in addition to
cmd(), you may also want to use
output_log().
Big output
Trying to dump the entire BGP table? (e.g. "show ip bgp") The default
buffer size is 1MB, so you'll have to increase it.
my $MB = 1024 * 1024;
$session->max_buffer_length(5 * $MB);
Sending multiple lines at once
Some commands like "extended ping" and "copy" prompt for
several lines of data. It's not necessary to change the prompt for each line.
Instead, send everything at once, separated by newlines.
For:
router# ping
Protocol [ip]:
Target IP address: 10.0.0.1
Repeat count [5]: 10
Datagram size [100]: 1500
Timeout in seconds [2]:
Extended commands [n]:
Sweep range of sizes [n]:
Try this:
my $protocol = ''; # default value
my $ip = '10.0.0.1';
my $repeat = 10;
my $datagram = 1500;
my $timeout = ''; # default value
my $extended = ''; # default value
my $sweep = ''; # default value
$session->cmd(
"ping
$protocol
$ip
$repeat
$datagram
$timeout
$extended
$sweep
");
If you prefer, you can put the cmd on a single line and replace every static
newline with the "\n" character.
e.g.
$session->cmd("ping\n$protocol\n$ip\n$repeat\n$datagram\n"
. "$timeout\n$extended\n$sweep\n");
Backup via TFTP
Backs up the running-confg to a TFTP server. Backup file is in the form
"router-confg". Make sure that file exists on the TFTP server or the
transfer will fail!
my $backup_host = "tftpserver.somewhere.net";
my $device = "cisco.somewhere.net";
my $type = "router"; # or "switch";
my $ios_version = 12;
my @out;
if ($type eq "router") {
if ($ios_version >= 12) {
@out = $session->cmd("copy system:/running-config "
. "tftp://$backup_host/$device-confg\n\n\n");
} elsif ($ios_version >= 11) {
@out = $session->cmd("copy running-config tftp\n$backup_host\n"
. "$device-confg\n");
} elsif ($ios_version >= 10) {
@out = $session->cmd("write net\n$backup_host\n$device-confg\n\n");
}
} elsif ($type eq "switch") {
@out = $session->cmd("copy system:/running-config "
. "tftp://$backup_host/$device-confg\n\n\n");
}
Sending control characters
Use
print() if you expect to get a prompt back. Use
cmd() if you
don't.
$session->print("\c^"); # send control-^
$session->cmd("\cZ"); # send control-Z
See also: "ios_break()"
SUPPORT¶
http://NetTelnetCisco.sourceforge.net/
Mailing lists
nettelnetcisco-announce is for important security bulletins and upgrades.
Very low traffic, no spam,
HIGHLY RECOMMENDED!
http://lists.sourceforge.net/lists/listinfo/nettelnetcisco-announce
nettelnetcisco-users is for usage discussion, help, tips, tricks, etc.
http://lists.sourceforge.net/lists/listinfo/nettelnetcisco-users
nettelnetcisco-devel is for uber-hackers; you know who you are.
http://lists.sourceforge.net/lists/listinfo/nettelnetcisco-devel
Help/discussion forums
http://sourceforge.net/forum/?group_id=48856
Bug tracker
http://sourceforge.net/tracker/?group_id=48856
SEE ALSO¶
Net::Telnet
Net::SNMP
UCD NetSNMP -
http://www.netsnmp.org/
RAT/NCAT -
http://ncat.sourceforge.net/
AUTHOR¶
Joshua_Keroes@eli.net $Date: 2002/12/31 00:12:32 $
It would greatly amuse the author if you would send email to him and tell him
how you are using Net::Telnet::Cisco.
As of Mar 2002, over 200 people have emailed me or posted to the
Net::Telnet::Cisco site. N::T::C is used to help manage over 14,000 machines!
Keep the email rolling in!
THANKS¶
The following people understand what Open Source Software is all about. Thanks
Brian Landers, Aaron Racine, Niels van Dijke, Tony Mueller, Frank Eickholt, Al
Sorrell, Jebi Punnoose, Christian Alfsen, Niels van Dijke, Kevin der Kinderen,
Ian Batterbee, Leonardo Cont, Steve Meier, Andre Bonhote, Rob Patrick, FtR,
James "mcaizjb3" Brown, and Hiro "Paul" Protagonist.
Paul gets a ++ for code-ninja skills.
Institutions: infobot.org #perl, perlmonks.org, sourceforge.net, the geeks at
geekhouse.org, and eli.net.
Send in a patch and we can make the world a better place.
COPYRIGHT AND LICENSE¶
Copyright (c) 2000-2002 Joshua Keroes, Electric Lightwave Inc. All rights
reserved. This program is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.