Configured my ADSL modem, lost my IP...

Posted on 2003-03-13
Medium Priority
Last Modified: 2013-11-29

I have an Alcatel ADSL modem. I've recently configured it to use PPP, so it is always connected to my ISP provider without any need to run dialup on my pc (XP pro).

I have a static IP, and since I've re-configured my modem, the IP went to the modem, and the modem gave me an internal IP address. The problem is that I have a ftp and mail server, and no one can connect to them right now, since they get to the IP and it's the modem.

I guess this is a problem that can be fixed by configuration, but I don't know how to do that.
Any help?

Question by:yronnen
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
LVL 41

Expert Comment

ID: 8132507
You need to forward the port(s) to your internal ip
ports 21 and 110
I'm not sure how to do it on your particular modem, but it should be in the manual

Expert Comment

ID: 8133455
What version of modem is it?  You are obviously using one-to-one NAT (Network address translation).  Your options are manifold:

a) Utilize IP/Port Forwarding to forward specific ports from your WAN address to your LAN address.

b) If your modem has a DMZ function, you can place the computer in the DMZ and all traffic should be forwarded.

c) Turn NAT off.  Since you only have one static IP, this means you're only going to be able to use one PC.  However, it looks like you're saying that's all you're working with anyway.

If you'll let us know which modem you have, I'm sure we can provide step-by-step directions.

Expert Comment

ID: 8133461
I'd also like to add that dependent on your modem model, utilizing PPP does not necessarily mean it is always on.  Make sure you don't have it turned to On-Demand.  If you do, it's only going to authenticate when your PC is trying to pass traffic to the WAN.
Percona Live Europe 2017 | Sep 25 - 27, 2017

The Percona Live Open Source Database Conference Europe 2017 is the premier event for the diverse and active European open source database community, as well as businesses that develop and use open source database software.


Expert Comment

ID: 8133764
Here is how i do it:

create a dns pointer to your ip address something that is easy to remember. eg: mail.yourcompany.com

then configure your modem to forward port 25 (smtp) and 110 (pop3) to your mail server.

point your users mail clients to the friendly dns name and it should all work fine.



Expert Comment

ID: 8133940
You might be able to get your IP, by using a friends computer with internet access, go to his Start menu, run, "command", then type "ping mail.yourcompany.com" where mail.yourcompany.com is the address of either your ftp or mail server that your gave to other people.

Then the ping will print IP address, so you can use that number at your home.

If that doesn't work, I would configure your DMZ value on your router to point to your internal LAN address of the mail/ftp server.

Author Comment

ID: 8141874
My modem is an Alcatel Speed Touch Pro. Ver. 8706.
Software build 231...

Accepted Solution

blumley earned 1000 total points
ID: 8142836
yronnen, here is exactly what you need to do:

1) telnet to the modem (should have the same IP addy as your gateway)

2) type NAT

3) type  create protocol=tcp inside_addr= inside_port=20 outside_addr=0 outside_port=20 (replace with the internal IP of your server and 20 with the correct port if that's not what your using.)

4)type  create protocol=tcp inside_addr= inside_port=25 outside_addr=0 outside_port=25 (replace with mail server ports)

5) Type SAVE

6) Reset the modem and you should be good to go.  

Let me know if this doesn't work.  I work with these modems a lot, so I'll do everything I can to help you.

Author Comment

ID: 8143059
blumley, this is exactly what i did. I've also upgraded to 510 and saw the list of forwarded ports in the list on the web interface.

However, it still does not work. I've configured ports 110 and 25 but it's not working. It did work before configuring the modem this way.

I also typed the list command from the telnet interface and saw my configuration to the nat.

Any ideas?

Expert Comment

ID: 9670159

could you help me out in this question:


Thanks !

Featured Post

Turn your laptop into a mobile console!

The CV211 Laptop USB Console Adapter provides a direct Laptop-to-Computer connection for fast and easy remote desktop access with no software to install.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Learn how to PXE Boot both BIOS & UEFI machines with DHCP Policies and Custom Vendor Classes
WARNING:   If you follow the instructions here, you will wipe out your VTP and VLAN configurations.  Make sure you have backed up your switch!!! I recently had some issues with a few low-end Cisco routers (RV325) and I opened a case with Cisco TA…
In this tutorial you'll learn about bandwidth monitoring with flows and packet sniffing with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're interested in additional methods for monitoring bandwidt…
Monitoring a network: how to monitor network services and why? Michael Kulchisky, MCSE, MCSA, MCP, VTSP, VSP, CCSP outlines the philosophy behind service monitoring and why a handshake validation is critical in network monitoring. Software utilized …

770 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question