Ruslan Ermilov writes:

On Thu, Apr 22, 2004 at 11:54:15AM +0200, GiZmen wrote:
Hello,
Is there any way to change ttl of incoming packet to a lower value ?
I had tried min-ttl option in pf packet filter but this option only increase
ttl to a given value when ttl is lower than this value.
I have searched on google and mailing lists but i do not find any answer.
I am running Freebsd 5.2.1 and i am using pf as my packet filter.
You mean, make the IP forwarding decrement the IP TTL more than by one?


Cheers, -- Ruslan Ermilov [EMAIL PROTECTED] FreeBSD committer

i've seen some cable/dsl ips's to do this, they set the IP TTL to 1 on the downlink to the client. (as a lame attempt to stop people sharing their connection)
So if one put some sort of gateway on the dsl/cable modem, all the packets it receives are with IP TTL 1, and the gateway will not able to forward them to the internal network....... which is in my opinion 1-st ugly, and 2-nd, easily avoidable with min-ttl for example :)
but if pf has min-ttl it seems that max-ttl can be easily added.
also i think i've seen somewhere on the net a netgraph module that can modify ttl's and some other things. i think it's name was ng_mangle

--niki

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