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Re: NMAP Identity obscuring
From: Cameron L Palmer <palmer74 () pacbell net>
Date: Fri, 24 Nov 2000 14:20:58 -0800

I too was thinking about this from a all ports closed situation except ssh.
Setting the number sequence to comply with RFC 1948 (I think that is the
number) has been a long time practice.  But in my experimentation (limited)
I have had success in preventing NMAP from getting the identity of my
firewall.  This is more likely the fact that it doesn't respond to most
things, and SSH only from specific IP addresses. So this tends not to give
NMAP an opportunity to "ask" any telling questions.  But most of my ndd
tuning is more from a performance standpoint.  The identity obscuring is
sort of an after thought.

Here are the parameters I'm currently using on the gateways:

ndd -set /dev/arp arp_cleanup_interval 60000
ndd -set /dev/hme adv_100fdx_cap 1
ndd -set /dev/hme adv_autoneg_cap 0
ndd -set /dev/ip ip_forward_directed_broadcasts 0
ndd -set /dev/ip ip_forward_src_routed 0
ndd -set /dev/ip ip_forwarding 0
ndd -set /dev/ip ip_ignore_redirect 1
ndd -set /dev/ip ip_ire_flush_interval 60000
ndd -set /dev/ip ip_ire_pathmtu_interval 600000
ndd -set /dev/ip ip_respond_to_address_mask_broadcast 0
ndd -set /dev/ip ip_respond_to_echo_broadcast 0
ndd -set /dev/ip ip_respond_to_timestamp 0
ndd -set /dev/ip ip_respond_to_timestamp_broadcast 0
ndd -set /dev/ip ip_send_redirects 0
ndd -set /dev/ip ip_strict_dst_multihoming 1
ndd -set /dev/qfe adv_100fdx_cap 1
ndd -set /dev/qfe adv_autoneg_cap 0
ndd -set /dev/tcp tcp_close_wait_interval 60000
ndd -set /dev/tcp tcp_conn_req_max_q 1024
ndd -set /dev/tcp tcp_conn_req_max_q0 4096
ndd -set /dev/tcp tcp_fin_wait_2_flush_interval  67500
ndd -set /dev/tcp tcp_recv_hiwat 65535
ndd -set /dev/tcp tcp_slow_start_initial 2
ndd -set /dev/tcp tcp_xmit_hiwat 65535

At the end of /etc/system

set tcp:tcp_conn_hash_size=16384

set rlim_fd_max=32768

Any comments?

cameron palmer.
----- Original Message -----
From: "Ofir Arkin" <ofir () itcon-ltd com>
To: <cameron_douglas () email msn com>; <of () securityfocus com>;
<lance () spitzner net>
Cc: <nmap-hackers () insecure org>
Sent: Wednesday, November 22, 2000 04:47
Subject: RE: NMAP Identity obscuring


I have read the Article in the sysAdmin magazine, unfortunately it is not
enough to fool me :)

The article, for those who do not subscribed to SysAdmin, deals with
changing parameters with
Solaris so NMAP will not detect it. The article suggests changing the PMTU
policy, and harden the sequence
numbers sequencing.

But, there are a lot of other wild ideas we can use that will reveal the
Solaris box.
Changing the most common identification parameters will not hide the other
Sure, it will make the job harder, but not impossible.

Ofir Arkin  [ofir () itcon-ltd com]
Senior Security Analyst
Chief of Grey Hats
ITcon, Israel.


"Opinions expressed do not necessarily
represent the views of my employer."

-----Original Message-----
From: Cameron Palmer [mailto:cameron_palmer () hotmail com]
Sent: Sunday, November 05, 2000 2:50 AM
To: of () securityfocus com; ofir () itcon-ltd com; lance () spitzner net
Cc: nmap-hackers () insecure org
Subject: NMAP Identity obscuring

I know we have seen the argument before, but the recent SysAdmin magazine
has an article on Solaris security.  They recommend changing some NDD
parameters to obscure the identity of Solaris from nmap.  They have some
interesting points, which is essentially they aren't looking for that as
sole form of protection of the machine but merely make Solaris conform to
the RFCs instead of having its own quirks that give away too much
information.  I would normally be dissuaded from security by obscurity
arguments, but by taking out the things that make the OS unique and
to RFCs you do raise the ante as it were.  Additionally I've seeen some
other good OS tuning parameters with NDD that help performance that are a
good idea, like fixing your Quad card to having multiple MAC addresses
instead of the single hostid.  Apparently you can gain a 40% speed boost
a Checkpoint firewall. This came from the Checkpoint web site.  They have
number of recommendations for security related changes.

Any thoughts?


From: Oliver Friedrichs <of () securityfocus com>
To: Ofir Arkin <ofir () itcon-ltd com>, Lance Spitzner <lance () spitzner net>
CC: nmap-hackers () insecure org
Subject: RE: firewalk meets nmap - TTL (tested)
Date: Sat, 04 Nov 2000 15:36:23 -0800
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 >Lance, we should automate this somehow. This is a cool thing.
 >But again correct configuration will prevent this from happening.

This is a really neat idea.  It should be easy to automate, if you
add in some traceroute functionality to nmap to determine the hop
where packets are being dropped (this would be the firewall), then
you only need to specify an address on the internal network.  I think
nmap could use UDP/TCP ACK/ICMP traceroute functionality anyways.
And while your at it, make it parallel, send out 32 packets with
incrementing ttl's at the very start.. none of this 1 hop at a time

- Oliver

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