From the Help Desk...the HKU ACEnet, Hallnet and VPN facilities

In the last issue, we looked at how to access the HKU network from home via the telephone lines using the PPP service. In this issue, we shall look at accessing the network from the residence halls (Hallnet),  the Access-Everywhere network (ACEnet), and accessing the HKU network from an ISP (Internet Service Provider)'s broadband service.

The Hallnet and ACEnet

In all the University's residence halls, network points are installed for every hall resident.  Students can plug in their desktop PC's or notebook computers to the network points in their rooms and connect directly to the HKU network.

In the ACEnet,  network points are installed on the walls in most major buildings in the university campus. Staff and students can use these ACEnet points for connecting to the network typically using a notebook computer.  Click here to find out the locations of these network points all through the campus.

The Network Interface Card

Before you plan to use the Hallnet or the ACEnet, you must obtain a Network Interface Card (NIC) for your computer. At present, all networking from PCs need the network card (except the PPP service which uses the modem as the network  interface).  The network card is what identifies your PC (with a machine number) to the network. Your network card has an ethernet address (EA) that is unique in the world.

You must register the EA of your network card with Computer Centre so that our network system recognises you as a legitimate user, otherwise the system will not allow access to those who did not register their network cards.  You can register your network card via the staff or student intranet.

When you connect to the Hallnet or the ACEnet, you will be assigned an IP address by the DHCP (Dynamic Host Configuration Protocol) server. The DHCP is the protocol that dynamically assigns IP addresses in the PPP dial-up system as well.

Your IP address is a unique number which identifies you on the Internet. If someone else is using the same IP address, then the browser will display an error message that there has been an IP address conflict and you will not be served the web page you requested.

If you wish to check the IP address you had been assigned by the DHCP, click Start...Run in your windows, then type the 'winipcfg' command in windows. If your IP address does not start with '147.8...' then it is wrong.  Be sure to select the correct network adaptor.  For hallnet and ACEnet, select the 'Ethernet adaptor', not the 'PPP adaptor'.  Then click the 'Release' and 'Renew' buttons at the bottom of the 'winipcfg' screen to release the last assignment and get a new IP address.

Moving in the Halls

For hallnet users, your name must be registered in the hall where you are staying before you can register your network card. Contact your hall manager about your hall registration if the intranet system will not allow you to register your network card properly.

If you had moved from one hall to another, you cannot use the network in the new hall. You must delete your previous network card registration in the student intranet system and then re-register it again under the new hall.

Broadband and VPN

More and more users are subscribing to the broadband service instead of using the PPP dial-up service for faster speed on the Internet.  Broadband refers to telecommunication that provides multiple channels of data over a single communications medium typically using your cable TV line (with higher bandwidth) instead of the telephone line.

When you use the broadband service, you are subscribing to an ISP.  When you connect to the HKU network from an ISP, you can only view contents placed on the HKU web server ( but not contents on the intranet such as the Student Connect system, the UIS system etc.

To access systems installed on the HKU intranet using an ISP's network service, you must use our VPN service. The VPN connection makes use of the Internet's routing infrastructure to move secure data to and from a private network, maintaining privacy through the use of a tunneling protocol and security procedures. The details for configuring the VPN server and procedures for connecting to the HKU network can be found at

Currently, only Windows 95/98 operating systems are supported but not Windows 2000.  The equipment manufacturer for our VPN gateway decided to quit from the enterprise network market, and hence, there will not be any upgrade for our existing VPN gateway.  However,  it is our plan for the next development of the VPN service to support the Windows 2000 and hopefully other platforms as well.

The proxy server

A proxy server serves as a gateway for the security of the institution. It also serves as cache memory space for storing webpages.  If you request a webpage from an external site outside of HKU, the browser will first look for the page on the proxy server.  If it finds the page, it returns it to the user without searching on the Internet. If the page is not in the cache, the proxy server, acting as a client on behalf of the user, uses one of its own IP addresses to request the page from the server out on the Internet. When the page is returned, the proxy server relates it to the original request and forwards it on to the user.

When using the Hallnet, the ACEnet or the VPN networks, you must configure the proxy server in your browser or you will not be able to view sites outside of HKU.  As the proxy server may be moved to different hardware from time to time, you should configure for the automatic proxy. The automatic server location is at

Mabel Chau
Tel: 2859 8934

[Contents] [Next] [Previous]