1.0 Network Technologies
1.1 Explain the function of common networking
protocols
• TCP (Transmission Control Protocol)- Part of the TCP/IP suite which is a protocol suite used for the internet. This protocol can be used in other networks as well. This particular part of the suite is connection oriented where two systems perform a three-way handshaking session and establish and open dialog with other. This is the underlying protocol for webpage requests via HTTP and even secure HTTPS. Many other protocols utilize this part of the TCP/IP suite. The Transport Layer-(Layer 4 of OSI Model)-Lowest level that has user services to layers above.
Also has the following responsibilities.
-Error free data transfer. Breaks up and reassembles
data in large packets for transmission purposes. Packet
composition dependant on protocol.
-Sequencing for upper layers occurs here
-Flow control for the protocol in use
-ACK(Acknowledgement) of transfer or receipt of data
• FTP (File Transfer Protocol)- An
ancient file transfer protocol, as the name implies this allows the transfer of
Binary and ASCII character files (more about format types).
FTP operates on a client-server model in which a client authenticates itself to
the server in order to download or upload files. While this protocol is
incredibly fast and often used on the internet it has tremendous security
problems since there is no encryption model to protect the login credentials or
session. Hence for those who desire privacy and protection of data and data
transmission SFTP (SSH FTP), FTPS (FTP SSL), and/or FTP via a VPN style tunnel are often used. FTP can often be run via most Operating Systems via a command line utility or the browser.
• UDP (User Datagram Protocol)- Component of the TCP/IP suite. Utilizes IP
packets to send datagrams without any prior handshaking or prior established
communication. UDP focuses on less overhead and speed of the packet
being sent. Hence UDP packets can be duplicated, out of order, or lost all
together. They are stateless and if integrity needs to be maintained it must be
at a higher level or application. UDP can multicast. (Note: For More Info.)
Services that use UDP include DNS, VoIP, SNMP, DHCP, and
RIP.
• TCP/IP suite (Transmission Control
Protocol / Internet Protocol) This suite of protocols are the backbone of
internet communication. It supports session communications via TCP and
stateless multicasting capable services and protocols via UDP. Services and
Protocols that operate over the TCP/IP suite include but are not limited to:
DNS, SMTP, POP, VoIP, HTTP, HTTPS, FTP, SSH, and
Telnet.
• DHCP (Dynamic Host Configuration Protocol)- A protocol designed to assign configuration information to a client. A UDP datagram is sent via the client to the DHCP; this is a network wide broadcast (255.255.255.255) since the client doesn’t know the DHCP servers address. The server responds by using the clients MAC address. (Note: More
info)
• TFTP (Trivial File Transfer Protocol)- Was orginially designed as a
light version of FTP. It uses UDP instead of TCP; which FTP uses. Does not
support directory listing features nor does it support a
authentication mechanism. It simply allows read and write access.
• DNS (Domain Name System)- A system by
which UDP is used to query a server based directory of domain names to find a matching IP or IP pool such that the client’s application (ie-
browser) can create an association of the domain to the IP address. (example: yahoo.com = 143.134.343.3) This is necessary
because domains are not functionally routing addresses but IPs
are. The DNS system as a whole is a rather complex hierarchical
naming system. This system as a whole would take pages to write; for the time being remember it is a functional system but as has been recently discerned it is old and its methodology predates a comprehensive security approach to internet
communication. For this reason there are proposals such as DNSSEC.
