Kingsley,

 

Are you wanting to allow traceroute in both directions? 

 

Regards,

 

Tyson Scott - CCIE #13513 R&S, Security, and SP

Technical Instructor - IPexpert, Inc.

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From: [email protected]
[mailto:[email protected]] On Behalf Of Kingsley
Charles
Sent: Monday, January 25, 2010 5:01 AM
To: Piotr Matusiak
Cc: [email protected]
Subject: Re: [OSL | CCIE_Security] inspect icmp error

 

Hi Piotr

 

This is the ACL on the outside interface.

 

ciscoasa# sh run access-list 120
access-list 120 extended permit udp any any range 33434 33464
access-list 120 extended permit icmp any any echo
access-list 120 extended permit icmp any any unreachable
access-list 120 extended permit icmp any any time-exceeded
access-list 120 extended permit icmp any any echo-reply

 

With regards

Kings

On Mon, Jan 25, 2010 at 3:28 PM, Piotr Matusiak <[email protected]> wrote:

Kings,

Have you opened a hole for UDP packets (traceroute) in the outside ACL?

HTH,
--
Piotr Matusiak
CCIE #19860 (R&S, Security) 





2010/1/25 Kingsley Charles <[email protected]>

Hi Piotr

 

I did try that before sending this mail. The traceroute just prints "*" and
no Ip addresses are present.

 

How can you traceroute to an unstranslated IP address from a lower security
level interface. 

 

 

With regards

Kings

On Mon, Jan 25, 2010 at 2:51 PM, Piotr Matusiak <[email protected]> wrote:

Hi,

You must traceroute private (untranslated) IP address of the host in the
inside network to see the difference.

For example:

(lo0)R1 -10.1.1.0- (out)ASA(in) -10.2.2.0- R2(lo0)

Assuming you have the following translation on the ASA:
static (in,out) 10.1.1.99 10.2.2.2

Run the following command on R1:
traceroute <R2-lo0>

You will see that ASA translates ICMP time-exceeded or unreachable IP
address to 10.1.1.99 (if you have icmp error inspection enabled). If not,
you will see untranslated IP address of R2 (10.2.2.2).


HTH,
Piotr Matusiak




2010/1/25 Kingsley Charles <[email protected]>

Hi all

 

Can someone please let me know, where would we actually use "inspect icmp
error". I am not getting the right explanation.

 

http://www.cisco.com/en/US/docs/security/asa/asa80/command/reference/i2.html
#wp1726194

 

 

With inspect icmp error enabled, I tried to IOS traceroute from outside to a
host behind the ASA. With "set connection decrement-ttl", the internel
address is revealed. 

 

Do we use "inspect icmp error", to reveal the actual internal IP address?

 

 

 

With regards

Kings

 

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