Perl system file monitoring script

Script description:

The script can monitor the specified important files of the system. When the files are viewed or modified, the script will check the users and IP who recently logged in to the system, and email notifications. #! / usr/bin/perluse strict;use Mail::Sender;use Digest::SHA;my @ files= ('/ etc/passwd','/ etc/shadow','/ var/log/wtmp'); my $last_cmd= `last-2`; while (1) {my% md5_res;my% output;my @ change;foreach my $file (@ files) {$md5_res {$file} = MD5_digest ($file); while (1) {sleep 10 Foreach my $file (@ files) {if ($md5_res {$file} ne MD5_digest ($file)) {$output {$file} = "$file is changed";}; if (% output) {foreach my $key (% output) {print "$output {$key}\ n";} print "$last_cmd"; last;}; sub MD5_digest {my $file=shift;my $sha=Digest::SHA- > new ('256'); $sha- > addfile ($file); my $digest=$sha- > hexdigest;return "$digest" } sub Send_mail {my ($subject,$msg) = @ _; my $sender=new Mail::Sender- > MailMsg ({smtp = > 'mail.aaa.com',from = >' neo@aaa.com',to = > 'neo@gmail.com',subject = > $subject,msg = > $msg,auth = >' LOGIN',authid = > neo',authpwd = > '1234',}) or die "$Mail::Sender::Error\ n"; print "Mail sent ok";}