ITE 453 midterm

Syntax to search for string value "test" in the text file file.txt

$ grep test file.txt

Advantages of .htaaccess file

- .htaccess allows you to make changes on a per-directory basis when the user doesn't have the means to modify main Apache config files - .htaccess is placed in a certain directory and directives apply to that directory and all its subdirectories

Four legal context for Apache directives

- Server config files (ex- apache2.conf) - virtual host <VirtualHost> - Directory <Directory> - .htaccess

what is returned in HTTP processes?

- server response status line - headers - blank line (to separate headers and entity body) - entity body (data)

disadvantages of .htaccess file

- using .htaccess slows down your server - failure to control .htaccess may lead to security or other Apache misconfiguration

HTTP request PDU components

-client request line (request method, URI, HTTP version) -header fields -blank line -entity body

HTTP response PDU components

-server response status line (protocol version, status code, reason phrase) -header fields -blank line - entity body

What are the three methods HTTP/2 includes to decrease latency

1) Data compression of HTTP headers (to reduce data transferred) 2) Server Push (server sends the client more data for queries then requested to allow for the client to render a webpage without asking) 3) Pipelining of requests (multiple HTTP requests are sent over TCP connection w/o waiting for response

What are the four primary web server functions and one optional function

1) accept and intercept http requests from clients 2) retrieve content from disk- provide access control and security 3) run local CGI and Server Side programs 4) transmit reply to client via http response opt) perform other functions like logging transactions

What are the six advantages of Apache

1) it is free 2) open source and highly configurable 3) runs on multiple platforms (linux, unix, windows) 4) very scalable (runs both very large and very small sites) 5) fast response to HTTP queries 6) not bloated (only install features you need)

HTTP 1.0 vs 1.1

1.0- established separate TCP connections for each item 1.1- established persistent TCP connections meaning multiple documents can be transmitted over one connection. provides support for multiple virtual hosts on one server.

___ level response codes represent client errors

400

401 response code

401 Unauthorized, information is restricted, retry with proper authentication so client displays login box

rwx privledges

4= read, 2= write, 1= execute

apt-get install

APT-GET: install a package from the apt repository on your Linux system

400 Error

Bad Request, means server doesn't understand request

POST:

Client sends data, usually in HTML form, to accompany the HTTP request to server in Entity body. Used for requesting action. The data is not visible in the URL and it cannot be bookmarked or clicked back.

How HTTP/2 differs from 1.1

HTTP/2 changes how data is framed and transported between client and server, it allows the server to "push" content

.htaccess

a configuration file used by the Apache web server to apply directory-level configuration settings to a specific directory and its contents

directory index

a server-generated list displaying contents of a directory

Web server daemon

a system running in the background on the server such as print, email, webserver, FTP

System Process

any program that is executing on the system

What are MIME types

application, audio, image, message, multipart, text, and video

double reverse DNS lookup

caused when a website must convert a domain name to an IP address

htpasswd

command-line utility that is used to manage user authentication files for Apache web servers

Apache directives

configuration settings that control the behavior of the Apache web server

Discretionary access

depends on information supplied by an accessor (ex- username/password). uses a combination of authentication and authorization

site access control

determines which resources of a website need to be restricted, determine who can access (users and groups), and apply mandatory or discretionary access

ifconfig

displays network configuration data for your system

command to find contents of the apache2.pid file

grep "string to search" /var/run/apache2/apache2.pid

HTTP/1.1 HOST: header

identifies the virtual host name

What are the consequences of improper placement of a directive

improper placement of a directive in a non-supported context can cause Apache not to start in server config/virtual host/directory contexts

Mandatory access

limiting access based on an IP address or domain of the HTTP- request sender. users have to prove a need for information before gaining access.

AllowOverride

primary directive involved in controlling the use of the .htaccess file

What are the parts of the server response status line?

protocol version, status code, reason phrase

Request methods

request methods determine what to do with request types: GET, POST, (< main ones), HEAD, PUT, DELETE, TRACE, OPTIONS, CONNECT

Active site

sites with unique, distinct content on their front page

command for enabling site "test.com"

sudo a2ensite test.com.conf

command to change permissions on file or directory

sudo chmod ### file.txt

Document Hierarchy

the structure of how the various objects on a web document are organized and accessed

sudo init0 or sudo shutdown now -P

use to safely shutdown your system to run level 0 and then power it off

alias

used to allow web server to access documents in directories outside document hierarchy

Netmask

used to determine which part of an IP address is the netid and which is the hostid

ugo

user, group, others

Ports 0-1023

well-known ports because they have been assigned to specific services, cannot set anything on these ports unless you are root administrator user

apache2.pid

where Apache stores parent PID information of the master apache process

ps ax

Linux command that will list all currently running processes.

GET:

Retrieves information from the server and entity body is empty. This is the standard method for all server requests. The data is appended in the URL and the page can be bookmarked and clicked back.

HEAD:

Same as GET except there is only a header included. Good for verifying a particular HTTP response.

crontab

Schedule a command to run at a later time

What are the goals of HTTP/2?

The goals of HTTP/2 are to: - decrease latency and allow for faster load times on webpages - be highly compatible with HTTP1.1 - allow clients/servers to use HTTP1.1, HTTP2, or potentially other non-HTTP protocols