Sendmail Correctly As an Internal Mail Handler

Sendmail Mods — Using Sendmail Correctly As an Internal Mail Handler

Modifying the sendmail.mc file for internal servers….
Listed below are the changes to a default RH 9 /etc/mail/sendmail.mc file required to operate a mail server behind a corectly configured Sendmail gateway server. These intranet servers can send mail to local users, users on the gateway server, [...]

Using Sendmail Correctly From Your Dynamic ISP Address

Sendmail Mods — Using Sendmail Correctly From Your Dynamic ISP Address
Modifying the sendmail.mc file to make it work….
Listed below are the changes to a default RH 9 /etc/mail/sendmail.mc file required to operate a mail server behind a non-reversible IP address. This should work for DSL, cable modem and [shudder] dial-up. If you can’t do a [...]

SSH BLACKLISTING

The sshblack script is a real-time security tool for secure shell (ssh). It monitors *nix log files for suspicious activity and reacts appropriately to aggressive attackers by adding them to a “blacklist” created using various firewalling tools — such as iptables — available in most modern versions of Unix and Linux. The blacklist is simply [...]

Perl Script To Demonstrate DNS Lookups In Linux

This is what you can expect to see from this script (approximately):
host # ./double.pl www.google.com
#######################################################
#!/usr/bin/perl
#
# double.pl – Double Check That Hostnames Match The IP’s They’re Advertising
#
# 2008 – Mike Golvach – eggi@comcast.net
#
# Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License
#
use Socket;
if ( $#ARGV != 0 )      {
           print “Usage: $0 hostname\n”;    
            exit(1);
}
$entry = $ARGV[0];
$hostname1 = [...]

Move or migrate user accounts to from old Linux server a new Linux

www.nixcraft.com
 How do I Move or migrate user accounts to from old Linux server a new Cent OS Linux server including mails? This new system a fresh installation.
A. You can migrate users from old Linux server to new Linux sever with standard commands such as tar, awk, scp and others. This is also useful if you are [...]