fellow monks,

I'm putting together a script that will enumerate services running in my environment. Example:

my $sock = IO::Socket::INET->new(PeerAddr => $host,
                 PeerPort => $port,
                 Proto    => $proto);

if ($port == 21) {
while (<$sock>) {
$sock->print("blah");
my $server = $_;
chomp $server;
print $server;
}
}

elsif ($port == 22) {
while (<$sock>) {
$sock->print("\012\012");
my $server = $_;
chomp $server;
print $server;
}
}

elsif ($port == 80) {
$sock->print("HEAD / HTTP/1.0\012\012");
while (<$sock>) {
my $server = $_;
print $server;
}
}

[download]
I've noticed that in order to grab the server details for HTTP, I had to put $sock->print outside of the while loop. If I leave the $sock->print inside the while loop the HEAD request will not be sent to the web server. Can someone help me to gain a better understanding of why this is different from, say, a simple banner request to port 21 or 22. Of course, I would be interested learning if there is a better approach to obtaining this type of information.

cheers, -semio

In reply to banner grabbing by semio

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