Remote Access

VPN (Virtual Private Network) Frequently Asked Questions

When I have made a local ISP connection and tried to VPN into NTU network, I got this error message: "Remote Server is Not Responding"
- Make sure you do not enable 'Internet Connection Sharing' service on your system
- Make sure you have disable any personal firewall such as zone alarm (back to top)
I got this error message "Error 691: Access denied because username and/or password is invalid on the domain"
- You might have keyed in a wrong password and password is case sensitive.
- To verify that your password is correct, you can check your user password by accessing the NTU Outlook Web Access from any of your ISP
- Call the helpdesk for advice (back to top)
When I am on an external organisation network and I am trying to VPN into NTU network, I simply cannot get connected
- Most organisations have some form of firewall implementations on their IT network on the Internet gateway.
  
  NTUVPN requires the following port & protocol to work and is therefore required to pass through the Firewall.
  i. TCP port 1723 or PPTP and
  ii. Generic Routing Encapsulation (GRE) protocol for VPN channel
  Read more when VPN client is behind the corporate Firewall
- Please refer to your company MIS or IT administrator for more advise on this. (back to top)

After I have established VPN connection, why am I not able to surf Internet?
There are so many possible reasons but the possibilities are
- The host base Firewall such as Windows ICF or Zone Alarm is blocking the outgoing or returning web traffic
- The web browser's system files might be corrupted therefore preventing web surfing
- Certain computer viruses, worms or spyware might cause damage to the files or OS system registry associated to the web browser
- There could be traffic path or routing issue between your ISP and the NTU VPN network after the VPN connectivity is established (back to top)
PC user must perform basic trouble-shooting to ascertain that the problem of unsuccessful web browsing is not due to the computer or the web browser. The results of the following trouble-shooting will assist the CITS helpdesk staff\Administrator to isolate the source of the problem speedily.
1. Disconnect the VPN network. Access the Internet via the user's ISP network.
2. Reestablish VPN network services and try to access NTU web pages such as http://www.ntu.edu.sg or Exchange via outlook client.
3. Surf the local web sites such as http://www.singnet.com.sg and the International sites http://www.hotmail.com
4. Access local ISP email server via outlook client (back to top)