I would like to block entire traffic from SLES server to one host in my network. I've tried doing it it many ways but communication still works. For example I added two lines:

iptables -A INPUT -d -p tcp -j REJECT
iptables -A OUTPUT -d -p tcp -j REJECT

in /etc/sysconfig/scripts/SuSEfirewall2-custom
But it doesn't work. How to solve this problem?