NAT detection - Revision history

.FUF at 22:13, 25 November 2008

2008-11-25T22:13:04Z

.FUF at 20:52, 5 November 2008

2008-11-05T20:52:57Z

Johnhsawyer: /* OS fingerprinting */

2008-11-05T14:11:51Z

‎OS fingerprinting

.FUF: New page: '''NAT detection''' is the process of determining hosts running Network Address Translators (NATs). == Approaches == === Active detection === * Port sca...

2008-11-04T21:11:32Z

New page: '''NAT detection''' is the process of determining hosts running Network Address Translators (NATs). == Approaches == === Active detection === * Port sca...

New page

'''NAT detection''' is the process of determining hosts running [[Network Address Translator | Network Address Translators]] (NATs).

== Approaches ==

=== Active detection ===

* Port scanning

Some software [[Network Address Translator | NAT]] solutions (such as [http://www.kerio.com/kwf_firewall.html Kerio WinRoute Firewall]), as well as many hardware solutions, provide a control port, which allows users to monitor and control their server (e.g. using a web browser). These control ports can be easily detected by means of port scanning (see [[Nmap]]).

* Routing test

Some improperly configured [[Network Address Translator | NATs]] allow IP packets to be translated from an external network. Routing test can detect these translators by trying to contact external server (e.g. ''forensicswiki.org:80'') with modified routing tables.

=== Passive detection ===

==== IP TTL ====

[[Network Address Translator | Network Address Translators]] decrement IP TTL values of all translated packets.

==== Leaked real IP address ====

Some network protocols leak real IP address of a client. These protocols include:

* SMTP, HELO/EHLO commands:

<pre>
These commands are used to identify the SMTP client to the SMTP
server. The argument field contains the fully-qualified domain name
of the SMTP client if one is available. In situations in which the
SMTP client system does not have a meaningful domain name (e.g., when
its address is dynamically allocated and no reverse mapping record is
available), the client SHOULD send an address literal (see section
4.1.3), optionally followed by information that will help to identify
the client system.
</pre>

(see RFC 2821)

* DNS, reverse lookups to an external DNS server:

Reverse DNS lookups made to an external DNS server can leak information about hosts in an internal network.

* Oscar (ICQ), MSN, MRA (Mail.Ru Agent), direct connections.

==== Strict source port translation ====

Some network protocols use strict source ports for communication. These protocols include: NTP, Valve.

Non-heuristic port translators (such as ICS in [[Windows]]) always translate source port numbers.

==== [[OS fingerprinting]] ====

[[Network Address Translator | Network Address Translators]] can be detected by passively fingerprinting all transferred IP packets.

Generally, single host will not produce different OS fingerprints in a short period of time. However, this method can be extended to fingerprinting different hosts running the same [[OS]] by using IP IDs and [[TCP timestamps]].

== Links ==

=== Non-English ===

* [http://itdefence.ru/content/articles/obnaruzhenie_nat_i_proxy/ Обнаружение NAT и proxy], ITDefence, 2007
* [http://itdefence.ru/content/pages/antinat/ AntiNAT], PoC tool, ITDefence, 2006-2007

[[Category:Network Forensics]]

← Older revision		Revision as of 14:11, 5 November 2008
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	Generally, single host will not produce different OS fingerprints in a short period of time. However, this method can be extended to fingerprinting different hosts running the same [[OS]] by using IP IDs and [[TCP timestamps]].		Generally, single host will not produce different OS fingerprints in a short period of time. However, this method can be extended to fingerprinting different hosts running the same [[OS]] by using IP IDs and [[TCP timestamps]].
		+
		+	[http://lcamtuf.coredump.cx/p0f.shtml p0f] can do NAT detection using passive OS fingerprinting. It uses a variety of identifiers to create a score on the confidence level of device doing NAT.

	== Links ==		== Links ==

@@ Line 69: / Line 69: @@
 == Links ==
 === Non-English ===
 * [http://itdefence.ru/content/articles/obnaruzhenie_nat_i_proxy/ Обнаружение NAT и proxy], ITDefence, 2007
 [[Category:Network Forensics]]

@@ Line 5: / Line 5: @@
 === Active detection ===
-* Port scanning
+==== Port scanning ====
 Some software [[Network Address Translator | NAT]] solutions (such as [http://www.kerio.com/kwf_firewall.html Kerio WinRoute Firewall]), as well as many hardware solutions, provide a control port, which allows users to monitor and control their server (e.g. using a web browser). These control ports can be easily detected by means of port scanning (see [[Nmap]]).
-* Routing test
+==== Routing test ====
 Some improperly configured [[Network Address Translator | NATs]] allow IP packets to be translated from an external network. Routing test can detect these translators by trying to contact external server (e.g. ''forensicswiki.org:80'') with modified routing tables.
@@ Line 56: / Line 56: @@
 Generally, single host will not produce different OS fingerprints in a short period of time. However, this method can be extended to fingerprinting different hosts running the same [[OS]] by using IP IDs and [[TCP timestamps]].
-[http://lcamtuf.coredump.cx/p0f.shtml p0f] can do NAT detection using passive OS fingerprinting. It uses a variety of identifiers to create a score on the confidence level of device doing NAT.
+== Tools ==
 == Links ==
@@ Line 63: / Line 73: @@
 * [http://itdefence.ru/content/articles/obnaruzhenie_nat_i_proxy/ Обнаружение NAT и proxy], ITDefence, 2007
 [[Category:Network Forensics]]