SUSE / Novell :: Write IPTABLES Script To Block The ICMP Ping?

I was trying to write IPTABLES script to block the ICMP ping using the below mentioned command in OpenSUSE 11.2 Doing this in VMware.....

iptables -A OUTPUT -o eth0 -p icmp -j DROP

& then I tried to ping the different computer & it didnt allow me to ping.
Then I deleted using the command -

iptables -D OUTPUT -o eth0 -p icmp -j DROP

then I couldnt ping also. Another thing I found is my firefox is not connecting to the internet as well, but before writing the script, I can connect to internet.

I did a "dhclient" & iptables -F....