NAT issue

[ritesh.p]

Hi there,

I've got cisco 2620XM router.i'm configuring NAT on that. MY ISP has give us single(1) Public IP. so using that i want my user to use internet and using the same IP I want my remote user to access my mail server which is in my local LAN. How can I do that using single IP ? Please advice...

Ritesh

[preddyi]

1.If your ISP has given single IP apart from the WAN interface IP, then simply Configure to overload the WAN IP for Pc's to brows internet.

2.Use the single IP, configure static NAT pointing to your mail server.

or

If your ISP did not provide any routable IP apart from WAN IP.

1.Then over load WAN interface for PC's to brows internet

2.Configure static NAT (extended) with destination IP (WAN IP) TCP port on which your mail service is running pointing to mail server IP and port no.

psl refer for more information

http://www.cisco.com/en/US/tech/tk648/tk361/tk438/tech_protocol_home.html

[ritesh.p]

Thanks for the reply buddy..

I've got some idea on that..i'll try on that and let u know..

[ritesh.p]

Hi buddy,

>>1.If your ISP has given single IP apart from the WAN interface IP, then simply Configure to overload the WAN IP for Pc's to brows internet.

I've done it like this way...

interface FastEthernet0/0

ip nat inside

!

ip nat pool browsenet xxx.xxx.xxx.xxx xxx.xxx.xxx.xxx netmask 255.255.255.xxx

!

ip nat inside source list 12 pool browsenet overload

!

access-list 12 permit 192.168.0.5

access-list 12 deny any

>>2.Use the single IP, configure static NAT pointing to your mail server.

How do i configure this one... please advice

Ritesh

[preddyi]

Suppose your mail service is running on port 25 and ip address 192.168.0.1

In the global configuration just say

" ip nat inside source tcp static tcp 192.168.0.1 25 x.x.x.x 25 extendable "

Here x.x.x.x is the routable IP given by the ISP.

What happens here is, when some body sends traffic to x.x.x.x ip on port 25(TCP/UDP)

Your NAT router will forward the traffic to 192.168.0.1(Mail server)

All other traffic from internal network will get port address translated to the NAT pool, you defined.

regards