perl function gethostbyaddr

The gethostbyaddr function in Perl is used to retrieve information about a specific host, identified by its IP address.

Here's an example of using gethostbyaddr in Perl:

#!/usr/bin/perl

use strict;
use warnings;
use Socket;

# IP address of the host we want to look up
my $ip_address = "192.168.1.1";

# Convert the IP address to binary form
my $packed_ip = inet_aton($ip_address);

# Look up the host information by IP address
my $host_info = gethostbyaddr($packed_ip, AF_INET);

if (!$host_info) {
    die "Host with IP address $ip_address not found";
}

# Print the host information
print "Name: $host_info\n";

In this example, we first convert the IP address of the host we want to look up to binary form using the inet_aton function from the Socket module.

We then use the gethostbyaddr function to retrieve information about the host using its IP address. If the host is not found, we exit with an error message.

If the host is found, we print its name to the console.

When you run this script, it will print the name of the host with IP address 192.168.1.1 to the console, assuming that such a host exists and can be looked up. If the host is not found, the script will exit with an error message.

Note that gethostbyaddr performs a reverse DNS lookup to retrieve the host information, so it requires appropriate DNS resolution to be configured on the system. If DNS resolution is not available, or if the host does not have a valid DNS entry, this function may not be able to retrieve the host information.