1. 2440: 141 Web Site Administration Remote Web Server Access Tools Instructor: Enoch E. Damson

2. Web Environment Servers Some servers you can access remotely include: File Transfer Protocol (FTP) servers Network News Transfer Protocol (NNTP) servers Telnet Streaming Media Servers Remote Connection to Web Servers2

3. Running An FTP Server File Transfer Protocol (FTP) Used to shares files between networked computers Client and server programs available for all platforms FTP has been integrated into modern Web browsers Anonymous FTP Current primary use of FTP Allows access to FTP server without account FTP servers may be set up to restrict file access Users authorized to access files are "known" Remote Connection to Web Servers3

4. FTP Client/Server Interactions FTP utilizes two ports: Control port (port 21) – serves as a communication channel between the client and the server for commands/replies exchange Data port (port 20) – used purely for the data exchange FTP can operate in two modes: Active FTP – the FTP client does not make actual data connection to the server The client informs the server of its own port with a port command Passive FTP – the FTP client issues a pasv command to indicate that it wants to access data in passive mode Remote Connection to Web Servers4

5. Using an FTP Client Required for accessing an FTP server FTP clients may be text-based or graphical Accessing an anonymous FTP server with ftp Specify the server name after the ftp command Example: ftp ftp.ibiblio.org A username and password may be needed Enter anonymous as username Enter e-mail address as a password Following logon, ftp> prompt appears Enter commands to interact with the FTP server Enter bye to exit Remote Connection to Web Servers5

6. Communicating with FTP Command Description Example ftp host Initiates a connection to FTP server ftp 192.168.0.100 open host Once the FTP client has been started, opens a connection open 192.168.0.100 close Closes the connection but does not exit the FTP client close quit or bye Closes the connection and exits the FTP client bye ls filenames Displays filenames and can use wildcards ls *.rpm dir filenames Displays the long listing of files and their properties, such as the size and date the file was created dir *.rpm 6

7. Communicating with FTP… Command Description Example binary Transfer files in binary mode binary ascii Transfer files in text mode ascii get filename Downloads a single file get test.zip put filename Uploads a single file put testapp.zip mget filenames Downloads multiple files; used with wildcards mget sendmail*.rpm mput filenames Uploads multiple files; used with wildcards mput *.tif prompt no Stops prompting for each file when used before you use mget or mput prompt no prompt Starts prompting prompt 7

8. Communicating with FTP… Command Description Example hash Displays a hash symbol as files are being downloaded hash cd directory Moves to another directory on the FTP server cd /software lcd directory Moves to another directory on the client lcd /docs pwd Displays the current directory on the server pwd help command Finds very brief help on FTP commands; if used without a reference to a command, it will give you a list of commands available help mget 8

9. Using an FTP Client… Using a Web browser to access FTP sites Point browser to ftp server Example: ftp://ftp.hq.nasa.gov Browser logs on to FTP server Uses anonymous as username Uses e-mail address as password Browser creates HTML pages and file listings on the fly Manipulate displayed files using mouse Logging on to an FTP server with a user account Provides greater access to features of FTP service FTP administrator may still restrict activities Remote Connection to Web Servers9

10. Using an FTP Client… There are several FTP clients available One of the clients installed on the Fedora core is: gFTP: FTP specific graphical client Remote Connection to Web Servers10

11. FTP Servers Some FTP servers include: vsftpd (very secured ftp daemon) wu-ftp: Washington University FTP server Remote Connection to Web Servers11

12. FTP Servers… Three types of FTP users Anonymous: use ftp or anonymous as logon name Real: use a regular Linux user account Guest: use restricted regular user accounts Remote Connection to Web Servers12

13. Setting Up FTP Configuration Files… Define user classes to assign permissions by group Example of class including all three FTP user types class office real, guest, anonymous 192.168.100.0/24 All users logging on from given address are in office Define message files for screen display Contents automatically displayed by FTP server Controlling file actions permitted to FTP user Use series of directives naming file action Follow directive with yes or no Include class of user to which directive applies Remote Connection to Web Servers13

14. Understanding News Servers News servers allow threaded discussions You post messages in a newsgroup A newsgroup focuses on a single topic There are several public newsgroups available There are hundreds of gigabytes of information generated per day News servers can be set up for use within an organization 14

15. Telnet and Windows Telnet is not popular in Windows because telnet is text-based and Windows relies on a GUI However, there are many command-line utilities that can be used Before Windows, Microsoft networking depended on a single command net with many options cacls can be used to alter permissions netsh starts a networking shell which allows you to configure and display many network-related items 15

16. Understanding Streaming Media Services Used to transfer video and audio By default, UDP is used Although TCP and HTTP can be used because of firewall issues in an organization No single standard exists Broadcast methods unicast – each packet is sent individually to each client multicast – each packet is sent to many clients 16

17. Understanding E-Commerce Servers Can be as simple as a product list and a shopping cart Can be as complex as amazon.com Microsoft Commerce Server is an add-on to IIS Incorporates a number of features required for a typical e- commerce site Highly customizable 17