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New Member

IP address being bloacked??


I have a 1720, IOS 12.1

e0 -

Server IP -

It seems to be blocking IP address only from getting outside the network. I can't see any access lists in place. Any ideas??



VIP Purple

Re: IP address being bloacked??


does your server have IP address with a subnet mask of, and is the default gateway of the server ? Can you post your router config ?



New Member

Re: IP address being bloacked??

Yes, server is

gateway is

I am runnning W2k server with AD and DNS


scope -

all clients can reach internet

I am trying to use forwarders to point the client machines to external DNS for internet

When client machine configured to use DNS

they can't reach the internet. If iI config the external DNS addresses they reach no problem. W2K with forwarder set should point to the external DNS.

I have this set up on a test network at home and it works fine. Someone told me in a forum that is blocked by RFC1918. Is this true or is there something in my config that is blocking the IP?

Here is my config,

Current configuration : 1880 bytes


version 12.1

no service single-slot-reload-enable

service timestamps debug uptime

service timestamps log uptime

service password-encryption

no service dhcp


hostname Duct&Vent


logging rate-limit console 10 except errors

enable secret xxxx

enable password xxxx


memory-size iomem 25

ip subnet-zero

no ip finger

ip name-server

ip name-server

ip dhcp excluded-address


ip dhcp pool clients





ip inspect audit-trail

ip inspect max-incomplete high 1100

ip inspect one-minute high 1100

ip inspect name internet udp

ip inspect name internet tcp

ip inspect name internet ftp

ip inspect name internet smtp

ip inspect name internet realaudio

ip inspect name internet cuseeme

ip inspect name internet http java-list 99

ip inspect name internet h323

ip inspect name internet rcmd

ip inspect name internet streamworks

ip inspect name internet vdolive

ip inspect name internet tftp

ip inspect name internet sqlnet

ip inspect name internet fragment maximum 256 timeout 1

ip audit notify log

ip audit po max-events 100




interface FastEthernet0

ip address

ip nat inside

ip inspect internet in

speed auto


interface Serial0

no ip address

encapsulation frame-relay

frame-relay lmi-type ansi


interface Serial0.1 point-to-point

ip address x.x.x.x *(I x'd this out)

ip nat outside

frame-relay interface-dlci 40 IETF


ip nat pool internet netmask

ip nat inside source list 1 pool internet overload

ip classless

ip route Serial0.1

no ip http server


access-list 1 permit


line con 0

transport input none

line aux 0

line vty 0 4

password xxxx



no scheduler allocate



Re: IP address being bloacked??

Two important questions:

1. Can the clients ping the Win2k server IP?

2. Can the Win2k server get out on the Internet?

Double check the Win2K server mask and default gateway. The mask should be

"Someone told me in a forum that is blocked by RFC1918. Is this true or is there something in my config that is blocking the IP?"

ISPs do not route private IP blocks (RFC1918 IPs). This isn't your problem because your router is NATing your block of IPs to "legal" a legal IP.

New Member

Re: IP address being bloacked??


Yes the clients can ping the server

No the server cannot reach the internet

I will have to check the DNS server setting on the server. I will double check the mask and gateway.




Re: IP address being bloacked??

Be sure to see if the server can get to the Internet via pure IP (e.g. no DNS type stuff). This will simplify troubeshooting because the DNS config on the server could be wrong. Try and ping something out on the Internet by IP like your ISP or something.


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