Hi Sam,
This shouldn't be happening (as you are mentioning it). So probably
there are some details missing from your description that will explain this.
How are you seeing the source and destination addresses of the ping
packets? (debug in router? Sniffer in each host? Etc)
What type are the ICMP packets? (you should be able to see this either
on the sniffer or the debug... the types are: http://www.nthelp.com/icmp.html)
Are the source and destination hosts PC's connected to the router? (or
are you using loopback interfaces, etc)
The following link might help you
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094c32.shtml
By the way, I understand that when you change the Cisco router by a
freebsd system the host (192.168.2.1) seems to receive the same packet reply
but now the host acts differently... this is not possible... the host shouldn't
be able to tell whether the packet was sent from a cisco router or a freebsd
system (in both cases it receives src: 192.168.2.50----> dst:192.168.2.1 type=0
if it is a reply)... so we have something missing... if the host act
differently the this are different packets... (The only difference would be
the MAC address of the freebsd system and the this should remind us of ARP but
I won't go there if not required... this dependes on your answers to the
questions above)
Regards,
Manuel
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Matt Thompson
mthompson-at-brightsolid.com |puck.nether.net nsp|
Sent: Sunday, March 31, 2013 7:00 AM
To: Manuel Berrocal (mberroca); s m
Cc: [email protected]
Subject: Re: [c-nsp] how NAt works from outside to inside
Date: Sat, 30 Mar 2013 13:17:00 +0430
From: s m <[email protected]<mailto:[email protected]>>
To: [email protected]<mailto:[email protected]>
Subject: [c-nsp] how NAt works from outside to inside
Message-ID:
<caa_1sgggnvk-dpbs+2ostnlsedpubxszs3yttfvfy0kn3+k...@mail.gmail.com<mailto:caa_1sgggnvk-dpbs%2b2ostnlsedpubxszs3yttfvfy0kn3%[email protected]>>
Content-Type: text/plain; charset=ISO-8859-1
hello all
i am newbie in NAT and i have some problem. i want to have a dynamic nat and
this is my topology:
192.168.1.1-----> cisco 2800 ------> 192.168.2.1
and this is my configuration in cisco 2800:
interface GigabitEthernet 0/0
ip address 192.168.2.2 255.255.255.0
ip nat outside
ip virtual-reassebly in
duplex auto
speed auto
interface GigabitEthernet 0/1
ip address 192.168.1.2 255.255.255.0
ip nat inside
ip virtual-reassebly in
duplex auto
speed auto
ip nat pool t 192.168.2.50 192.168.2.60 netmask 255.255.255.0 ip nat inside
source list 1 pool t access-list 1 permit any
when i ping 192.168.2.1 from 192.168.1.1 (from inside to outside), every thing
is ok and nat is done correctly but when i ping
192.168.1.1 from 192.168.2.1 (from outside to inside), packets that received
in 192.168.2.1 are as below:
request packets: src:192.168.2.1----> dst: 192.168.1.1
reply packets: src: 192.168.2.50----> dst:192.168.2.1
and 192.168.2.1 system accept these packets as its reply!!! i think this
behavior is wrong, isn't it? how it is happen? moreover, if i put a freebsd
system instead of cisco, everything is the same except that
192.168.2.1 does not accept the reply packets as its reply (as i expected!!).
please let me know if the cisco behavior is correct or not and if it is
correct, how cisco router do that?
please help me if i am misunderstanding.
thanks in advance
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