how to only allow tcp on dport 443 on the OUTPUT chain?

[Bill Davidsen]

erikmccaskey64 wrote:
> it's a normal desktop machines iptables firewall:
>
> If i want to block udp on dport 80 on the output chain, then is this
> enough? i want to only allow tcp on it!
> iptables -P OUTPUT DROP
> iptables -A OUTPUT -o $PUBIF --dport 80 -j ACCEPT
>
> or i need this rule?
> iptables -P OUTPUT DROP
> iptables -A OUTPUT -o $PUBIF -p tcp --dport 80 -j ACCEPT
>
> the second one is the good one?
>
You don't want to do that, if you block everything on OUTPUT things like DHCP, 
ARP, ICMP, etc, fail. You would need pages of ACCEPT rules.

iptables -A OUTPUT -p tcp ! --dport 80 -j REJECT

Would at least block only tcp, although I bet you will find that you want to do 
mail and such. You are rapidly entering deep waters, I fear, but it's your machine.

-- 
Bill Davidsen <davidsen at tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot