Iptables rules sometimes are reset automatically

Solution 1:

sudo iptables -A INPUT -s 89.111.3.48 -j DROP

If you just run the above command, it just loads that rule into the kernel, not really changing the iptables file. This would be lost on a reboot or a restart of iptables.

service iptables save

would save the rules to /etc/sysconfig/iptables and the change would survive a reboot.