More efficient and flexible

raveguy2k has asked for the wisdom of the Perl Monks concerning the following question:

Greetings Monks,

My goal for this particular script is to go into a switch and find ports that are connected and then find ip's based on mac addresses and do an nslookup to find out what servers the ports are connected to. However my ultimate goal is to create a script that will allow one to go into a switch or a router and pull whatever information they want easily and quickly. This is where you helpful folks come in. How can I reduce the repitition in my code to make it more efficient by removing some of the for loops by taking advantage of some of perls idioms and are there any other ways of making the script more flexible so that whatever information I want from a router or script can easily be obtained? Here is some sample code:

use warnings;
use strict;
use Net::Telnet::Cisco;

my $session = Net::Telnet::Cisco->new(Host => 'xxx.xx.xx.xx);
$session->login('','password');
# no paging - disrupts output
$session->cmd('terminal length 0');

my @output1 = $session->cmd('show int status | include connected');
my @connected;
my @port;
my @macs;

# get only connected ports
foreach (@output1) {
    # should be splitting on those that are connected
    my @tmp = split(/ /, $_);
    # just get a stream of interfaces?
    push @port, $tmp[0];

    # create new command
    my $string;
    $string = "sh mac-address-table int $tmp[0]" if defined $tmp[0];

    # show what we get
    push @macs, $session->cmd($string);
}

# go through sh mac-address-table for connected interfaces
# get just mac address
my $cmd;
my @ip;
foreach (@macs) {
    if(m/(\.\w{4}\.\w{4})/) {
        $cmd = "sh ip arp | include $1";
        push @ip, $session->cmd($cmd);
    }
}

#extract ip and perform nslookup
foreach (@ip) {
    if(m/(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/) {
        print `nslookup $1`;
    }
}

$session->close;
[download]

Comment on More efficient and flexible Download Code

Replies are listed 'Best First'.
Re: More efficient and flexible by davido (Cardinal) on Dec 14, 2005 at 20:24 UTC
This is an untested snippet (I don't have a Cisco switch to telnet into), though it does compile. I've eliminated two of the three foreach loops by processing each port all the way through to an nslookup on each iteration of the single foreach loop. This eliminates the need for several of your single-use arrays. use warnings; use strict; use Net::Telnet::Cisco; my $session = Net::Telnet::Cisco->new(Host => 'xxx.xx.xx.xx'); $session->login('','password'); # no paging - disrupts output $session->cmd('terminal length 0'); my @output1 = $session->cmd('show int status \| include connected'); foreach my $out (@output1) { my $port = ( split / /, $out )[0]; next unless defined $port; my $mac = $session->cmd( "sh mac-address-table int $port" ); if ( $mac =~ m/(\.\w{4}\.\w{4})/ ) { my $ip = $session->cmd( "sh ip arp \| include $1" ); if( $ip =~ m/(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/ ) { print `nslookup $1`; } } } $session->close; [download] Any more terse than this would make it difficult to read and maintain, IMHO. I'd like to note that your original script was not really any less efficient except that it required storage of mac addresses, ports, and IP's. But that's minor. Doing things in stages as you originally coded isn't inherently slower. The three foreach loops perform the same tasks as my single foreach loop, but my single loop takes just as long. It just rearranges the order in a way that makes the script itself shorter. Updated to clean up the code further. One more thing (update): I did notice that when I compiled this with '`perl -c mytest.pl`', I got the following warning: `Use of /g modifier is meaningless in split at C:/Perl/site/lib/Net/Telnet/Cisco.pm line 756.`, which indicates an issue buried somewhere within Net::Telnet::Cisco. Probably insignificant, but one always wonders when a module spits out a warning. Dave	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re: More efficient and flexible
by davido (Cardinal) on Dec 14, 2005 at 20:24 UTC

This is an untested snippet (I don't have a Cisco switch to telnet into), though it does compile. I've eliminated two of the three foreach loops by processing each port all the way through to an nslookup on each iteration of the single foreach loop. This eliminates the need for several of your single-use arrays.

use warnings;
use strict;
use Net::Telnet::Cisco;

my $session = Net::Telnet::Cisco->new(Host => 'xxx.xx.xx.xx');
$session->login('','password');
# no paging - disrupts output
$session->cmd('terminal length 0');

my @output1 = $session->cmd('show int status | include connected');

foreach my $out (@output1) {
    my $port = ( split / /, $out )[0];
    next unless defined $port;
    my $mac = $session->cmd(
        "sh mac-address-table int $port"
    );
    if ( $mac =~ m/(\.\w{4}\.\w{4})/ ) {
        my $ip = $session->cmd( "sh ip arp | include $1" );
        if( $ip =~ m/(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/ ) {
            print `nslookup $1`;
        }
    }
}

$session->close;
[download]

Any more terse than this would make it difficult to read and maintain, IMHO. I'd like to note that your original script was not really any less efficient except that it required storage of mac addresses, ports, and IP's. But that's minor. Doing things in stages as you originally coded isn't inherently slower. The three foreach loops perform the same tasks as my single foreach loop, but my single loop takes just as long. It just rearranges the order in a way that makes the script itself shorter.

Updated to clean up the code further.

One more thing (update): I did notice that when I compiled this with 'perl -c mytest.pl', I got the following warning: Use of /g modifier is meaningless in split at C:/Perl/site/lib/Net/Telnet/Cisco.pm line 756., which indicates an issue buried somewhere within Net::Telnet::Cisco. Probably insignificant, but one always wonders when a module spits out a warning.

Dave

[reply]
[d/l]
[select]