Google for htpdate, or check out this, where you can get fairly accurate time from google servers.

#!/usr/bin/perl
use warnings;
use strict;
use IO::Socket;

# su to root first, unless sudo is setup correctly for the commands 

my $datecommand='date -s';  #'set system time' command

my $request ="HEAD / HTTP/1.0\r\nHost: \r\nUser-Agent:zzzdate\r\nPragm
+a: no-cache\r\n\r\n";

my $socket = IO::Socket::INET->new    (
    Proto        => 'tcp',
    PeerAddr    => 'www.google.com',
    PeerPort    => 80
) or die "Can't connect $!\n";

# Send HEAD requests
print "$request\n";
print $socket $request;

while (defined (my $res = <$socket>) ) {
    print "$res\n";
    if ( $res =~ /Date: / ) {
        # Like-> Date: Wed, 22 Oct 2008 18:30:46 GMT
        $res =~ s/Date: //;
        #print "$res\n";
        print "Setting time... ", `$datecommand \"$res\"`;
    }
}

close $socket;

#zero out adjtime if time keeps getting thrown off unexpectedly
#open (TH,"> /etc/adjtime") or die "$!\n"
#close TH;
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