Server Application Software
• File Service Allows File Sharing
– File server stores program and data files
– Can be accessed by any user with access rights
– Built into most SOSs
Access Rights
File
Server
No Access Rights

Server Application Software
• File Service
– For sharing application program files also
– No need to install applications on each PC
• Greatly reduces installation labor
File
Server

Server Application Software
•
File Server Program Access
– Program is STORED on the file server
File
Server

Server Application Software
• File Server Program Access
– But program is EXECUTED on the client PC
– Limited by power of client PCs, which do not get very large
File
Server

Server Application Software
• Typical Application Software
– Word processing, e-mail, etc.
– Must buy multiuser versions, not just a single copy from a retail store
– License will limit the number of users
– Will cost more than the SOS

Server Application Software
• Print Service
– Also built into SOSs
– Print jobs go to shared printers
– But they first go to the file server
– Not directly to the print server!
Print Server
Client PC
File Server
Shared
Printer

Server Application Software
• Print Service
– File server stores print job in a print queue until print server is ready to print it
– File server sends the print job to the print server
Print Server
File Server
Shared
Printer

Server Application Software
•
Print Server
– Print server feeds the print job to the printer
– Print servers are simple and inexpensive because the file server does most of the work
– Low print server cost allows shared printers can be scattered throughout the office
Print Server
File Server

Server Application Software
• Print Server
– Connects to printer via parallel port on the print server; no special printer needed
– Has NIC to connect to the hub or switch
– Requires an RJ-45 port on the hub or switch
Print Server
RJ-45 Port
UTP
Parallel Cable

Server Application Software
• Print Server Location
– Parallel cable distance limitation requires print server to be within 1-2 meters of the printer
– UTP allows print server to be up to 100 meters from the hub or switch
RJ-45 Port Print Server
UTP (up to 100 m)
Parallel Cable
(1-2 m only)

Server Application Software
•
Remote Access Service (RAS)
– User dials into a remote access server
– Server authenticates the user (user must prove identity)
– If authenticated, user may use internal services
– Client PC needs RAS software
Internal
Server
RAS
RAS
Client
Software
LAN
Dial-Up
Telephone
Line
Dial-In
Client

Server Application Software
• Internet Access for a Simple PC LAN
–
Serial Router
– Simple, inexpensive router
– One RJ-45 port for LAN, one suitable port for
ISP Connection
Access
Line
Serial Router

Server Application Software
• Serial Routers
– May provide security to stop outside hackers
• Network address translation (NAT) hides addresses of internal machines
• Only serial router’s IP address appears in outgoing packets
Serial Router Access
Line
IP Packet with Serial
Router’s IP Address

Server Application Software
• Serial Routers
– Provide security to stop outside hackers
• May provide a firewall (discussed in Chapter 10) to prevent unauthorized access from Internet hackers
Serial Router
Access
Line

Server Application Software
•
Directory Servers
– Problem: Most networks have many servers
– To use a resource, must know the server
• To send e-mail, address is user@server
• Files must be accessed on particular servers

Server Application Software
• Directory Servers
– Directory server knows all resources on all servers
– Can send mail to user (without @server)
– Can search for a specific file across servers
Directory
Server

Server Application Software
• Directory Servers
– Know user access rights on all servers
– Single login to directory server
– Get access to all other servers where user has access rights
Directory
Server
Single
Login