Changing packets ttl's

[GiZmen]

Hi,

I am searching how to change packet ttl. I am runing a freebsd 5.4
gateway and i would like to change ttl of any packets that are
going out from my internal interface. My goal is to change ttl to 1
so the last hop is the next host in my internal network.
I want to prevent people to do small NAT in my network. I know that
changing ttl's is easy to bypass but not for normal user :)
I am using pf as my packet filter but there is no option to change
ttls to smaler value. Please help me with this problem.
Big thanks 

-- 
Best Regards:
		GiZmen

UNIX is user-friendly; it's just picky about its friends
UNIX is simple; it just takes a genius to understand its simplicity