Firewall Configurations
Firewall are also configured manually by the users which means that user can add or remove filters on the basis of different conditions and terms. Here are the some examples
IP Address
Each device on the internet is assigned by unique address and that address is known as IP Address. IP Address is based on 32 bits and is consists of four octets separated by dotted decimal numbers. IP Address typically looks line 192.168.1.254. For example, if specific ip address which does not exists in the company network is reading huge number of files from the server then firewall will block all the incoming and outgoing traffic from that ip address.
Domain Names
As we all known that it is difficult to remember the numbers which are used to make the ip address and for some times there is the need to change the ip address of the device that's why there is also the name of server like human name. For example it is easy for the user to remember www.google.com as compare to 216.58.205.36. Any company can block access to specific or all users to the some domain names or they will allow access to some specific domain names. The user who wants to connect and communicate with the server have to use the protocol which is pre-defined for that specific service. Protocols are usually in text form and they describe that how client and server will communicate with each other. Here are the some common protocols that can be used and filtered with the help of firewall are:
Internet Protocol (IP)
It is main system of delivery for information over the internet.
Transmission Control Protocol (TCP)
Used to transfer or rebuild the information which is travelling over the internet.
Hyper Text Transfer Protocol (HTTP)
This protocol is used for web pages.
File Transfer Protocol (FTP)
This protocol is used to upload and download the files from the server.
User Datagram Protocol (UDP)
This protocol is used for the transmissions which don't requires response from the user or other devices e.g., recorded or live streaming of audio and video.
Internet Control Message Protocol (ICMP)
This protocol is used by routers to exchange their information with other connected routers.
Simple Mail Transport Protocol (SMTP)
This protocol is used to transfer information which is based on text such as e-mail.
Telnet
This protocol is used to configure device remotely.
Ports
All the machines which act as server uses numbered ports of internet usage to provide their services and one port for each service on the server which available.
For example if a single server is running both the services of HTTP and FTP then HTTP uses port number 80 and FTP uses port number 21.
Specific word and phrases
Specific word and phrases will be any thing. In this process firewall examines or search the each packet which is passing through it for the information which will exactly matches with the phrase listed in it filter.
For example, you have instructed the firewall to block the packet having the word "X-Ray" then filter will only block the packet containing exactly matched word, it will not block the packet having "X Ray" (without hyphen). User can add as many as words and statements to the filter list of firewall.
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