[c-nsp] IP NAT help

[christopher.a.kane at jpmchase.com]

Do you have a route for that network? NAT is irrelevant if there is no 
route.

sorry for the top post (my mail app sucks)

-chris





"Ivan c" <ivannetw at gmail.com> 
Sent by: cisco-nsp-bounces at puck.nether.net
08/28/2006 11:57 PM

To
cisco-nsp at puck.nether.net
cc

Subject
[c-nsp] IP NAT help






Hi All,

I have an issue with NAT as was looking for some guidance. Thanks up 
front!

I have an external router that does both source and destination NAT of the
addresses.

                                                             fa0/0
fa0/1
Customer RTR<---------------------------------------->My
RTR<------------------------------------->internal host (172.30.13.xx)
Source 203.13.xx.xx                                         NAT source
172.30.10.xx
Dest 203.6.xx.xx
dest     172.30.13.xx

Traffic imitated from 203.13.xx.xx to 203.6.xx.xx gets NATed at my router 
to
an internal source address of 172.30.10.xx and a destination of 
172.30.13.xx
.

So I tried the following

interface Fa0/0
ip nat outside

interface Fa0/1
ip nat inside

ip nat inside soruce static 172.30.13.xx 203.6.xx.xx
ip nat outside source static 203.13.xx.xx 172.30.10.xx

I do a tcpdump on the inside interface (mirror port on switch) and I see 
the
traffic destined for the internal host using the NAT addresses, but when 
the
internal hosts tries to syn back to my router, the router sends back a 
icmp
destination host unreachable?

Thanks
Ivan
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