TELNET QUESTION

Hello, Can someone give me a quick pointer as to why is it that i'm not able to telnet into this router unless I put the following command ip nat inside source static tcp 209.42.x.x 23 209.42.x.x 23

Thanks,

User Access Verification

Password: ima_test>en Password: ima_test#show config Using 1689 out of 129016 bytes ! version 12.2 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname ima_test ! enable password xxxx ! ! ! ip subnet-zero ip cef ! ! no ip domain-lookup

! ! ! ! ! ! ! fax interface-type fax-mail mta receive maximum-recipients 0 ! ! ! ! interface FastEthernet0/0 ip address 192.168.1.1 255.255.255.0 ip nat inside duplex auto speed auto ! interface Serial0/0 no ip address shutdown ! interface FastEthernet0/1 no ip address shutdown duplex auto speed auto ! interface Serial0/1 no ip address shutdown ! interface ATM1/0 no ip address no atm ilmi-keepalive ima-group 2 scrambling-payload ! interface ATM1/1 no ip address no atm ilmi-keepalive ima-group 2 scrambling-payload ! interface ATM1/2 no ip address no atm ilmi-keepalive scrambling-payload ! interface ATM1/3 no ip address no atm ilmi-keepalive scrambling-payload ! interface ATM1/IMA2 no ip address no atm ilmi-keepalive ima differential-delay-maximum 75 ! interface ATM1/IMA2.1 point-to-point ip address 209.42.x.x 255.255.255.0 ip nat outside pvc 1/69 ! ! interface ATM1/IMA2.2 point-to-point ip address 10.128.35.4 255.255.255.0 pvc 1/70 ! ! ip nat inside source list 1 interface ATM1/IMA2.1 overload ip nat inside source static tcp 209.42.x.x 23 209.42.x.x 23 extendable ip classless ip route 0.0.0.0 0.0.0.0 209.42.x.1 no ip http server ! access-list 1 permit any ! call rsvp-sync ! ! mgcp profile default ! dial-peer cor custom ! ! ! ! line con 0 line aux 0 line vty 0 4 password xxxx login ! ! end

ima_test#

Reply to
bvlmv
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It is because you have NAT with overload (PAT) setup on interface ATM1/IMA2.1

Effectively PAT does not allow inbound connections. With PAT the outside address is not mapped to any particular host, it is shared between many hosts on the LAN. Adding the "inside source static" statement for port 23 gives it something to map to and that is why it works.

You could have also mapped the FastEthernet1.1 address to the ATM1/IMA2.1 address

Regards,

Martin

Reply to
Martin Kayes

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