07-21-2008
Webpage to Telnet via Perl and Expect: Telnet problem?
Somewhat long story:
I have a simple Perl CGI script that uses Expect to Telnet to a device and grab some data, and then spits it back to Perl for display on the Webpage.
This works for many devices I've tried, but one device just fails, it keeps rejecting the password on this device, only accepts one character.
I have sniffed out the traffic and the interaction seems to be valid.
The only clue i think i found is the Telnet negotiation, which I discovered from the telnet debug code:
But when it is spawned by the webpage, there is a difference in this line of code Telnet debug code:
SENT IAC SB NAWS 0 0 (0) 0 0 (0)
The CGI script runs fine when launched from the shell, and shows this code:
SENT IAC SB NAWS 0 80 (80) 0 24 (24)
So...I have given up on everything else, all I can think is that the device, possibly poorly coded and non-compliant, is crapping out on the Web server environment with 0 0 for columns and lines.
If this is the issue, does anyone know a way to force Telnet into standard 80x24 mode, or ignore the negotiation?
This equipment is discontinued and cannot go back to manufacturer to fix their Telnet code.
Thanks
JD
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LEARN ABOUT DEBIAN
net::cli::interact::manual::cookbook
Net::CLI::Interact::Manual::Cookbook(3pm) User Contributed Perl Documentation Net::CLI::Interact::Manual::Cookbook(3pm)
NAME
Net::CLI::Interact::Manual::Cookbook - Miscellaneous recipes
Windows Support
The library works just fine under native windows (i.e use something like Strawberry Perl - no need for cygwin), for Telnet, Serial and SSH
connections. However one additional step is required for you to have success:
You must download the "plink.exe" application, and pass its filesystem location in the "app" parameter to "new()". Do not try to use any
other Telnet or SSH programs (for instance the Windows bundled "telnet") - they will not work. Here's an example:
my $s = Net::CLI::Interact->new(
personality => "cisco",
transport => "Telnet",
(Net::CLI::Interact::Transport::is_win32() ?
(app => "$ENV{HOMEPATH}\Desktop\plink.exe") : () ),
);
Unix Support
The library works fine on most Unix platforms. It will try to use the native "telnet", "ssh" (openssh) and "cu" programs for Telnet, SSH
and Serial connections, respectively. If you want to use another application, pass it in the "app" parameter to "new".
In some Unix environments there can be zombie child processes left around after running your script. If this happens, set the "reap"
option, like so:
my $s = Net::CLI::Interact->new(
personality => "cisco",
transport => "Telnet",
connect_options => {
reap => 1,
},
);
Phrasebook Entries
Prompts
These are nothing more than named regular expressions:
prompt configure
match /(config[^)]*)# ?$/
Macros
This example waits for the device to ask "[startup-config]?" and then responds with the text "startup-config".
macro copy_run_start
send copy running-config startup-config
match /Destination filename [startup-config]?$/
send startup-config
To send instead a press of the Return key (output record separator), use:
macro write_mem
send copy running-config startup-config
match /Destination filename [startup-config]?$/
send ''
To instead allow the user to pass in the file name, use a "sprintf" format.
macro save_to_file
send copy running-config startup-config
match /Destination filename [startup-config]?$/
send %s
The user must then pass a parameter to the "macro" call, even if it's an empty string:
$s->macro('save_to_file', { params => ['file_name'] });
# or
$s->macro('save_to_file', { params => [''] });
Continuations
These are Macros which start with a match instead of a send:
macro more_pages
match / --More-- /
send ' '
Note that the parameter of the "send" is not sent with a Return character (output record separator) appended.
When included in a macro, the continuation can be in-line, like this:
macro show_ip_route
send show ip route
follow / --More-- / with ' '
Running Commands
Standalone Commands
Simply send the command you wish to execute to the library. If not already done, a connection to the device will be established
automatically:
$s->cmd('show ip int br');
Normally this matches against a default prompt, which has been discovered automatically, or set by you:
$s->set_prompt('user_prompt');
It's also possible to pass in a custom prompt for this command only:
$s->cmd('show ip int br', { match => qr/special prompt>$/ });
Composite Macro Commands
Call a predefined Macro from the phrasebook using this method:
$s->macro('write_mem');
Sometimes the Macro needs parameters:
$s->macro('to_priv_exec', { params => ['my_password'] });
You can't really create a Macro on the fly very easily, but with suitable use of "cmd()", "set_prompt()", and the "match" option to "cmd()"
it's possible to achieve some simple flexibility.
Reconfiguring On-the-Fly
Phrasebook
It's possible to load a new phrasebook by the following method, which must be passed at least the name of the personality:
$s->set_phrasebook({ personality => 'ios' });
You can pass any options which the Phrasebook module itself would take.
Prompt
The current prompt can be changed by passing the name of the new Prompt as it is known by the phrasebook:
$s->set_prompt('name');
If you want to test whether the current prompt matches a diffrent named Prompt from the phrasebook, this method can be used:
$s->prompt_looks_like('name');
perl v5.14.2 2012-06-12 Net::CLI::Interact::Manual::Cookbook(3pm)