Network Protocols

In computer networks, a protocol refers to a set of common rules that enable different and unrelated devices to communicate with each other. Having a set of common standards promotes the development of networks (how much easier would international relations be if everyone in the world spoke just one language?).

Network protocols are constructed in layers, meaning that small parts of a particular protocol can be developed independently, without interfering with the rest of its functionality.

The Internet protocol suite is the set of communications protocols used for the Internet and other similar networks. It is commonly known as TCP/IP, because of its most important protocols: Transmission Control Protocol (TCP) and Internet Protocol (IP), which were the first networking protocols defined in this standard.

TCP/IP Protocols

Protocol Meaning Application
DNS Domain Name System Translates domian names such as cssouth.uk into and IP address
TLS / SSL Transport Layer System / Secure Sockets Layer Crytpographic protocols designed for secure communications
FTP File Transfer Protocol For copying files from one host to another
HTTP Hyper Text Transfer Protocol For distribution of hypermedia files (web pages)
HTTPS Hyper Text Transfer Protocol Secure For encrypted transfer of data via web pages (secure banking and shopping)
IMAP Internet Message Protocol Used to send and recieve email
POP3 Post Office Protocol (version 3) Used to send and recieve email
SMTP Simple Mail Transfer Protocol Used to send and recieve email

Network Security

When data is being transmitted across a network it is possible that it might be intercepted by unauthorised people and misused. This is a particular issue with wireless networks, where signals are more easily captured.

Access levels

Users on a network do not need to see all the data. As with a DB, different users have different needs so can be given different permissions. Checks can be made when a user logs on to a network – their userID / password are checked against a DB of authorised users and appropriate privileges are granted based on a set of rules determined by the network manager. Access privileges will range from Access Administrator rights (access all areas) down to lowest levels where users are restricted to viewing / editing specific files. As well as enhancing security, this also makes life easier for the average user by removing access to lots of unnecessary data and files.

Passwords

Each userID is password protected. Hackers may try to access accounts by guessing likely passwords. Brute force methods can be used in which a software program will use every possible combination of characters until the correct password is found. Passwords can be made more difficult to guess by increasing the number of characters used, mixing upper and lower case letters and including numbers and characters. Regularly changing a password will also enhance security.

Encryption

If data could be intercepted by an unauthorised person, security can be maintained by encrypting data before it is transmitted across the network.

It is harder to enforce security across a wireless network as anyone within range could potentially access the data being transmitted within it. An older method of encrypting data within a wireless network is known as WEP (Wired Equivalent Privacy). This method encrypts data using a single password as the encryption key but is not particularly secure. A more robust method is to use WPA (Wi-Fi Protected Access), which uses a similar method but dynamically generates a new 128-bit key for each packet sent. WPA also includes a message integrity check to ensure that data packets are not interfered with. WPA2 is the successor of WPA and is even more robust through its use of stronger algorithms. Provided a long enough password is used, WPA2 is virtually uncrackable... unless someone reveals the key.