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If you have a local area network (two or more computers connected in a network, that is, each having a network card) with one computer connected to the Internet (via a modem, using a cable, etc.), it may be useful to make the Internet accessible to the other computers on the network (the clients) by installing a software program that will serve as a proxy server.

A proxy makes it possible to share a connection, that is, it gives the network's computers access by proxy, by redirecting information (generally web pages requested by the LAN's computers).

However, the more users there are, the lower the bandwidth for each of them will be, since the users share the proxy's bandwidth with each other... For example, if 8 people are connected to a modem at 56,000 bauds, only 7,000 bauds will be left per person, or...not much: no point for 8 people to be surfing the Web...

Setting up the server

The server will be the computer on the local area network that is connected to the Internet. To be able to use the Jana server, you need to make sure the TCP/IP protocol is correctly installed on the computer that will be used as server (Control panel/Network).

If the server is connected to the Internet via a modem, the following two protocols should appear in the control panel/network window:

• TCP/IP -> NE2000 compatible card (or the name of the network card connected to the local area network)
• TCP/IP -> Remote access card

You need to make sure the IP address (click the name of your card then go to the properties tab) of the NE2000 compatible card is 192.168.0.1 (it may be different but this is the address that is usually given to the proxy). The properties of the remote access card's TCP/IP protocol are provided by your Internet service provider, so there is no point in modifying them!

If the computer is connected to the Internet via a network card (cable, ADSL or other), there are two possibilities:

• The server has two network cards (one connected to the internet - via a cable modem for example - and the other connected to the local area network); the TCP/IP protocol needs to be defined for the two cards. In this case the following two protocols should appear in the control panel/network window:
  • TCP/IP -> NE2000 compatible card (or the name of the network card connected to the local area network)
  • TCP/IP -> NE2000 compatible card (or the name of the network card connected to the Internet)
• The server has only one network card. In this case you need to use a hub by connecting all of the LAN's computers to the hub with a straight-through cable, and the modem with a cross-over cable.

  

Then configure the subnet mask to 255.255.255.0

Setting up clients

Each of the machines on the local area network is connected via a network card (using a BNC or RJ45 cable). As in the case with the server, you need to set up the TCP/IP protocol on all of the machines connected to the server (the clients) and assign them a unique IP address.

• in the case of an ADSL connection, you need to assign them the addresses 10.0.0.X (X being a unique value from 11 to 255 for each client)
• otherwise, you need to assign them the addresses 192.168.0.X, 192.168.0.3 (X being a unique value from 2 to 255 for each client)

Installing the proxy server

The next step involves retrieving the proxy server (software). We will use Jana Server, a free and efficient proxy server you can download from CCM:
Download here! (size 300KB)

Once the download has finished, double-click the executable file then follow the instructions (the first messages are merely warnings, of no use if you correctly followed the previous steps).

Configuring the server

After the installation and launch, a red "J" should appear in your taskbar. Simply double-click on it, then select "configuration" (you will be asked for a password. Enter the password of your choice and make sure you'll remember it :).

By default, Jana is configured to manage only connections from the web (HTTP protocol).

• To surf the net, check Behave as Https, Ftp, gopher proxy
• If no other similar service is launched, you can check all the services that interest you

The number of threads represents the maximum number of users that can simultaneously connect via the proxy, whereas the maximum number of connections represents the total number of sessions the users can open (a user can open several sessions at the same time)

Moreover, the Proxy,Socks page defines the ports that are assigned to each of the services. By default, the HTTP port will be 8080, the SOCKS port will be 1080 (SOCKS4 and 5), and the port assigned to RealAudio will be 1090/554.

Configuring clients

To make it possible for clients to access the Internet, it is necessary to configure each application to specify that the connection is being made via the proxy.

All recent Internet-related applications (browsers, FTP clients, ICQ, etc.) have a "proxy server" option sometimes mistakenly called a firewall; this option may look like this:

In the address field, you need to enter the address of the machine being used as server (that is, 192.168.0.1 in general) as well as the port associated with the application (8080 by default).

Configuring the Internet browser

To configure your internet browser, simply go to preferences (options, configuration...) and find the option "connect using a proxy server".
In the first field, enter the proxy's address (192.168.0.1) and in the second enter the port (8080). Some browsers will ask you for proxy addresses for each service, the two main services being http and ftp, for which you will complete the field as described above.

To configure IE4

• Select View/Internet Options/Connections
• Under proxy server check Access the Internet using a proxy server and click Advanced
• Under proxy server/address, enter the server's IP address (192.168.0.1 in theory)
• Under proxy server/port, enter the port you assigned to the server (by default, 8080)

To configure IE5

• Select Tools/Internet Options/Connections/LAN settings...
• Under proxy server check use a proxy server and click Advanced
• Under server/proxy address to use, enter the server's IP address (192.168.0.1 in theory)
• Under server/port, enter the port you assigned to the server (by default, 8080)

To configure Netscape

• Select Edit/Preferences/Advanced/Proxies
• Check Manual configuration, then click view
• Under server/proxy address to use, enter the server's IP address (192.168.0.1 in theory)
• Under server/port, enter the port you assigned to the server (by default, 8080)

Configuring an FTP client

Programs such as CuteFTP, WS_FTP, etc. generally have an option in the preferences that lets you specify the address of a proxy server; in this case enter the address of the computer running Jana server (192.168.0.1) then enter port 21.
You have the option of entering a password if you restricted access on Jana server by assigning passwords to the local area network's users.

This process will give the network's computers access to FTP sites on port 21. To be able to access FTP sites on other ports, you will need to use FTP clients that accept the SOCKS service. SOCKS is a service that makes it possible to dynamically open ports on the proxy, and is the only way to be able to use applications whose port is variable (FTP on ports other than 21, IRC, etc.)

Configuring a messaging client

Messaging or e-mail is the most widely used service on the Internet; it is therefore essential that you be able to use it when sharing a connection on a local area network. The e-mail service includes two main functions:

• e-mail sending (SMTP)
• e-mail receiving (POP3)

Configuring e-mail involves

• defining real configuration options (those provided by your ISP) on the machine being used as proxy
• defining virtual users (corresponding to users of the local area network) in Jana server
• configuring messaging clients on the local network's other machines by providing them with the address of the machine being used as proxy server).

The first operation involves configuring each user in the email users tab in Jana Server, then adding as many users as there are machines connected to the local area network.

The local settings field will contain a name, an e-mail address, a login and a virtual password for the user (settings the user will enter in its messaging client). The name of the SMTP server will be that of the machine connected to the internet, and the e-mail will be that of the user. The settings of the POP3 account will be those of the user, as if it were his machine.

Each user must configure his messaging client with the items entered in the Local Settings field of Jana Server.

Appendix

The software program Jana Server as well as similar free software programs are available in the downloading area of this section. The configuration of network computers follows the same procedure with the other software programs. For more details, refer to the help guides for these programs.

If you have questions, feel free to ask them in the forum!