This possible mark packet for ttl in mikrotik 3.0?
execuse my bad english.
I need to block ttl <128, to permit only packet ttl 128 (windows) and ttl 64 (linux), for sharing block, in Linux is simple, but, in mikrotik I don´t.
This is possible in new mikrotik (beta)?
You can change the TTL with mangle rules.
Here is an example that changes the TTL to 1 for all packets destined for 192.168.10.*
/ip firewall mangle add action=change-ttl chain=postrouting disabled=no dst-address=192.168.10.0/24 new-ttl=set:1
This does not work perfectly, I need only allow the tll 128 and ttl 64, to set ttl for 1, no working perfectly and allow windowx xp sharing
Have you tried setting the TTL to 0?
-Louis
yes, not working, ttl 0 no break sharing connection.
About this subject: I tried it and sniffed the packets. TTL is being changed. But Win ICS is still able to share the connection, I don’t know, maybe MS did something.
So for now on two networks we are doing the reverse thing - detecting ttl that is not 128 and not 64 and adding the client to a list or marking the packets.
But this is still stupid because 90% of these bastarbs use a home router. And the competition lets 'em have whatever TTL so … this is useful when theres no competition.
I use TTL to hide routers from traceroute 
when TTL changes?
A: Each time the packet pass through L3 device (Firewall, Router, Nat,…) TTL = TTL - 1.
I’ve tried the follow setting in my L2 network:
ip firewall mangle add chain=postrouting action=change-ttl disabled=no new-ttl=set:0 passthrough=yes out-interface=bridge-la
n
No nat/routing between clients and Mk and it works perfectly! 
Best regards,
Iván Carrasco Q.