RE: PIX and ttl

["Fernando Cardoso" <fernando.cardoso () whatevernet com>]

> > I'm doing a pen-test for a client that has a "standard" config of
> > router-firewall-server_in_dmz. I'm fingerprinting the setup and
> I'm aware
> > that the firewall is a Cisco PIX (BTW is there any way to
> change the banner
> > for the fixup protocol smtp? :)
> no way, but i think that security configuration of the MTA behind
> the pix it's
> thw right way and that "fixup protocol smtp" isn't necessary.
> It simply add overhead to the Firewall processing...

Fully agreed.

> > Their router is at 5 hops of distance from me. Both router and
> fw gives me
> > the ttl I was expecting when I ping them (251 and 250), but all
> the servers
> > in the DMZ don't...
> >
> > traceroute to server_in_dmz (x.x.x.x), 30 hops max, 38 byte packets
> >  1  a.a.a.a (a.a.a.a)  2.068 ms  2.031 ms  2.349 ms
>   TTL:255
> >  2  a.a.a.a (a.a.a.a)  153.681 ms  152.925 ms  131.445 ms
>   TTL:254
> >  3  a.a.a.a (a.a.a.a)  205.197 ms  269.539 ms  145.973 ms
>   TTL:253
> >  4  a.a.a.a (a.a.a.a)  38.078 ms  23.849 ms  23.497 ms
>   TTL:252
> >  5  router (router)  31.445 ms  27.277 ms  28.422 ms
>   TTL:251
> >  6  * * * (fw)
>   TTL:250
> >  7  * * * (server_in_dmz)
>   TTL:123
> > The servers in the DMZ are Microsoft boxes so the "right" TTL
> should be 122.
>
> No, it's different from release to release of microsoft products...

I don't think so... I've tested all kind of Windows stuff and I always get
128 (local LAN). Maybe the results you're showing are the result of some
kind of "PIX tweaking".

> -- Windows NT 4.0 x86 SP6a ( ttl = 128 ) in MY LAN
> 46 bytes from 10.1.3.20: flags=SA seq=0 ttl=128 id=25884 win=8576
> rtt=0.5 ms

OK

> -- Windows 2k x86 SP1 ( ttl = 123 ) behind PIX 5.3(1)
> 46 bytes from xxx.xxx.xx.xxx: flags=SA seq=0 ttl=123 id=10872
> win=8576 rtt=27.3 ms
>
> -- Windows NT 4.0 x86 unknown SP ( ttl = 118 ) behind 5.3(1)
> 46 bytes from xxx.xxx.xxx.xxx: flags=SA seq=0 ttl=118 id=45018
> win=32768 rtt=860.1 ms

Are these two on the same network? If my guesses are correct the first one
would be at 7 hops from your box (like in my example) and the second one at
12 hops.

> -- PIX Itself 5.3(1)  ( ttl = 247 )
> 64 octets from xxx.xxx.xxx.x: icmp_seq=0 ttl=247 time=87.7 ms
>
> -- PIX Itself 5.1(4)  ( ttl = 251 )
> 64 octets from xxx.xxx.xxx.xx: icmp_seq=0 ttl=251 time=102.4 ms

Same hop distance these two?? That would be odd.

> As you could see ttl it's different for the same pix release...
> I HATE PIX, I HATE CISCO ;>

Time for a Checkpoint FW-1 :)

--
Fernando Cardoso - Security Consultant       WhatEverNet Computing, S.A.
Phone : +351 21 7994200                      Praca de Alvalade, 6 - Piso 6
Fax   : +351 21 7994242                      1700-036 Lisboa - Portugal
email : fernando.cardoso () whatevernet com     http://www.whatevernet.com/



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