The Internet is truly a client-server environment. There is a myriad of services available on the Internet ranging from e-mail to the World-Wide Web. Each of these services require both client and server computer systems. Throughout this book, the focus has been on the client side of the Internet. We have looked at e-mail clients, telnet and ftp clients, gopher and web clients. This chapter looks at the other side, the Internet servers.

In order to access any of the services available on the Internet, the computer providing the service must be a "server". This doesn’t mean that the computer has to be a large, powerful machine. It simply means that the computer must be running the appropriate server software. Servers can be UNIX computers, Macintosh computers, IBM mainframes, VAX minicomputers and most PCs running Windows or some other networking operating system. In all cases, the server should be connected to a dedicated Internet connection. The appropriate server for the service to be provided must be installed on the computer that will be the server. Remember that there are different servers for different services. Just because a computer is running a Web server, it does not mean that the server also supports ftp or e-mail or any other service. It might, but the appropriate server software must be installed.

Many operating systems come provided with several servers. For instance, most versions of UNIX come with an e-mail server, an ftp server, and a telnet server. Most versions of Windows NT come with a simple ftp server. Windows NT 4.0 Server includes Microsoft’s Internet Information Server (IIS). If the server is not included with the operating system, then you will need to either purchase or obtain a copy of the server for your computer and operating system. Many of these servers are either public domain or free for educators. This chapter will discuss several of these servers and where to obtain them.

E-mail servers are probably the most complicated of all Internet servers. This is because of the variety of protocols and features that may be necessary for the e-mail service. All e-mail servers need to support the SMTP (Simple Mail Transfer Protocol). SMTP allows for the sending and receiving of e-mail between the client and server. It unfortunately does not allow you to access e-mail via a 3^rd party e-mail client program like Eudora or Netscape Mail. To use 3^rd party e-mail client programs, the e-mail server must support another protocol called POP3 (Post Office Protocol version 3) or IMAP4 (Internet Message Access Protocol version 4). These protocols allow for the mail to be stored and forwarded on demand from the server. Most e-mail servers now support POP3 and many are now beginning to support IMAP4. IMAP4 supports remote connectivity features including off-line usage, partial downloading of messages, and mailbox synchronization.

Other features that are beginning to appear with e-mail servers are:

• Remote Administration via the Web
• Mail-to-Pager Capability
• Mail-to-Fax Capability
• Integrate with Existing Web Technology including Support for HTTP and MIME
• LDAP (Lightweight Directory Access Protocol)
• ListServ Capability

Most versions of UNIX, VMS, and MVS include e-mail servers and do not need any additional work to get up and running once the computer is networked. There is a wealth of e-mail servers available for Windows NT and several of them are free or relatively cheap. Among these are:

• 11.2.1 Netscape Mail Server 2.02

(http://home.netscape.com/try/comprod/mirror/server_download.html)

• IMail Server (http://www.ipswitch.com)
• Post.Office (http://www.software.com)
• EMWACs (http://www.emwac.ed.ac.uk/html/internet_toolchest/ims/ims.htm)

There are many others that can be located on the Web at sites like http://tucows.myriad.net/server95.html#mail and others. MailServ that comes with the NT 4.0 Server Resource Kit should be avoided. It will grab all of the available resources from the server.

Netscape Mail Server 2.02 is available in versions for Windows NT and 95, UNIX and Macintosh at

http://home.netscape.com/try/comprod/mirror/server_download.html. It is free for educators and educational institutions.

To install the server on a Windows NT system, follow these instructions:

1. Create an account and group for the Mail Server service using NT’s User Manager (as an administrator). The account and group should be specifically for the Mail Server and should have no other members or groups. [Select "User Cannot Change Password", "Password Never Expires" and do not select "User Must Change Password at Next Login". The account must have the "Logon as a Service" enabled.
2. For NT workstation, use local user and local group. For NT Server, use global user and global group. Make sure that the Mail Server user account has membership in both the Mail Server and Administrators groups.
3. Run SETUP.EXE to install the mail server.

If you have any problems, answers to FAQs and technical notes are available at http://help.netscape.com/server_info/mail20guide.html

IMail 4.0 is available from http://www.ipswitch.com for Windows NT. It includes features for Remote Administration via the Web, Mail-to-Pager Capability, Mail-to-Fax Capability, LDAP (Lightweight Directory Access Protocol), ListServ Capability, and an AntiSpamming feature. Its greatest plus is that it uses the NT user database for authentication so that you do not need to build separate databases for NT users and e-mail users. There is a free 45-day evaluation version available from Ipswitch. The commercial version costs $495 minus a 10% discount for educational institutions.

Setup involves unzipping the file into a temporary directory and running SETUP.EXE. As with other servers, you will need to set up an administrative account complete with a password. You will also need to specify the domain for the e-mail accounts.

Post.Office is available from http://www.software.com for Windows NT and UNIX. There is a free 10-user version as well as a $495 commercial version for 100 users.

EMWACs Internet Mail Services is available from http://www.emwac.ed.ac.uk/html/internet_toolchest/ims/ims.htm for Windows NT. It is free to download. The installation is explained in detail at http://www.emwac.ed.ac.uk/html/internet_toolchest/ims/install.htm.

A World Wide Web server, is a program that responds to an incoming HTTP connection and provides a service to the client. This usually involves returning a requested HTML document but now may include other services. There are many varieties of server software to serve different forms of data. Servers are available for most environments including UNIX, Windows NT and ’95, Macintosh and others. Use Tucows (http://www.tucows.com), Yahoo or Altavista to search for others.

CERN server

The W3 daemon program, full featured, with access authorization and research tools. This daemon is also used as a basis for many other types of server and gateways. Platforms: Unix, VMS.

A server for files, written in C, public domain. It includes as many features as CERN's httpd. Platforms: Unix. [http://hoohoo.ncsa.uiuc.edu/docs/Overview.html]

A server for Windows NT provided by Computer Software Manufaktur. Image-maps are not supported. [http://www.csm.co.at/csm/alibaba.htm]

Service for NT. Configurable using control panel. [http://www.w3.org/hypertext/WWW/HTTPS/Status.html]

Server for the Macintosh. [http://www.w3.org/hypertext/WWW/MacHTTP/Status.html]

Available for a variety of platforms at http://home.netscape.com/comprods/

Commercially supported server from Netscape Communications Inc. A freeware version is available for Windows NT. [http://home.mcom.com/MCOM/products_docs/server.html]

A server for NT and Win95 from O'Reilly. (Currently running on my computer at http://csc.ColumbusState.edu/summers). [http://website.ora.com]

A Windows server created by Robert Denny. Will not run on Windows 95 and NT.

[http://www.city.net/win-httpd/].

Runs on all Windows platforms. Sixty-day evaluation available. [http://www.zbserver.com]

Available for free with Windows NT 4.0 Server. Will also work on NT 4.0 Workstation and Win 95.

WebSite can be freely downloaded for educational institutions and educators from http://software.ora.com/download/. It downloads as a zip file that needs to be uncompressed into a separate directory. Before running the website11e.exe file, you need to find out the domain name (mine is jaring.nmhu.edu) or the IP address (mine is 192.132.89.167) of the computer that you are installing the web server on. You will also be asked to give an e-mail address for the web administrator. During the installation, you will be asked to identify the default directory (Website’s default is c:\website\httdocs) and the default homepage (Website’s default is default.*). These are important. Clients of your site will be able to access anything within your default directory, so choose wisely. The default homepage will be the HTML document displayed if the client does not specify a file name.

IIS is provided free along with a gopher and an ftp server with Windows NT 4.0 Server. When you install NT Server, you will be asked if you wish to install IIS also. If you choose to install it, you will be asked similar questions to those described above for Website. If you do not install it during the NT Server installation, you can install it later. IIS is also available free from http://www.microsoft.com for installing on Windows NT Workstation.

FTP servers allow remote ftp clients to connect to the server and upload / download files. When setting up the ftp server, it is important that a large degree of security is invoked since clients will have access to the server’s files. You will need to determine who will have access to the server and what level of access (i.e. read-only) will be permitted. You will also need to determine if "anonymous’ logins will be allowed.

Ftp service is usually built-in to most UNIX systems and Windows NT systems. There are several ftp servers listed at http://tucows.myriad.net/server95.html#ftp.

A very simple ftp server to install is QVT/NET FTP. After downloading the QVTNET software, simply run the ftpd.exe file, specify which directories are to be accessible and by whom and whether anonymous ftp will be supported.

Other servers include

1. News servers (two good ones are Netscape’s News Server and Dnews [available from http://world.std.com/~netwin].
2. Telnet servers (not widely used on PCs, although there is a free version for NT)
3. Gopher servers (not widely used anymore)
4. IRC and chat servers (a good one can be found at http://www.parachat.com/)

Remember that an appropriate server must be installed on the "server" computer in order to use the designated service. HAVE FUN.