Introduction To TCP/IP Protocols

Before you begin!

Objectives: Learn about significant TCP/IP protocols in the TCP/IP model.

Prerequisites: No prerequisites.

Key terms: Port, protocol, transport, network, UDP, TCP, FTP, IP, layer, control, internet, host, and HTTP.

What Is A Protocol?

Protocol in networking is actually a set of rules and standards for communication between the network hosts. Protocols frequently offer services, like file transfer or email. The majority of protocols carry out a particular function.

However, the majority of protocols aren’t able to perform each aspect of networking by itself. The majority of protocols depend on other protocols for a full networking solution.

A group of protocols that are to be utilized together is known as the protocol suite. The most well-liked protocol suite is actually the TCP/IP protocol suite. This protocol suite is a set of protocols that are utilized on the web and on the majority of networks. For checking the IP address, you can make use of what’s my IP-free tool by duplichecker.com.

TCP/IP Model:

The Internet protocol suite or TCP/IP Model is a set of communications protocols that are utilized on the web and similar networks. It’s referred to as the TCP/IP because of its most significant protocols: Transmission Control Protocol (TCP) and Internet Protocol (IP).

Such protocols were the first networking protocols described in this standard. The TCP/IP protocol suite has four abstraction layers (in contradiction of the OSI model, which has seven), each has its own protocols. From highest to lowest, the layers are:

• The Application Layer: It handles the app-based interaction on a process-to-process level between the communicating Internet hosts.
• Transport Layer: It can handle host-to-host communication.
• Internet Layer: Connects diverse networks.
• Link Layer: It can handle communication on the local network.

Application Layer Protocols:

A few of the renowned protocols that reside at the application layer of the OSI (Open Systems Interconnection) model are FTP, DNS, DHCPv6, DHCP, LDAP, IRC, IMAP, HTTP, POP, NTP, NNTP, MGCP, SIP, RTSP, RTP, RPC, SSH, SOCKS, SNMP, SMTP, XMPP, TLS/SSL, and Telnet, etc.

• HTTP:

The first protocol that we’re gonna discuss is HTTP (Hypertext Transfer Protocol). This protocol defines how sites exchange HTML docs. The protocol, in fact, recognizes how the web browser submits the request to a server that holds the site, and how a server formats that data for returning it back to the web browser, and then how the web browser shows the information.

HTTP can be explained as the information requesting & responding protocol. This protocol makes use of port number 80 by default and predominately utilizes TCP as a transport protocol, although it can utilize UDP as well. Another related protocol is HTTPS. In this one, another protocol is appended to HTTP that is called Secure Socket Layer or simply SSL.

SSL is a way of encryption that actually protects the data while moving through a network. It makes use of the RSA for encryption and authentication. The browsers utilize the Secure Socket Layer for ensuring safe Web transactions. URLs that start with https:// make the Web browser to utilize SSL. HTTPS is the secure form of HTTP that utilizes Secure Socket Layer for encrypting data before its transmitted.

HTTPS and HTTP are both transmit protocols that describe how sites send information. HTTPS, by default, utilizes port number 443 and utilizes TCP as a transport protocol. HTTPS ought not to be taken for the little-used S-HTTP (Secure HTTP). Another protocol that is similar to SSL is Transport Layer Security or TLS.

Basically, they both offer encryption, but they’re diverse in implementation. A protocol that makes use of the TLS can’t make use of SSL and vice-versa. SSL is almost certainly more extensively implemented, although Transport Layer Security is more advanced than Secure Socket Layer because it comprises other functionalities.

TLS makes sure that the messages being transmitted on the web are tamper-proof and private. Transport Layer Security is implemented through 2 protocols: TLS Record (can offer connection security with encryption (with DES, for instance)), and TLS Handshake (offers the choice of encryption method and mutual authentication).

• FTP & TFTP:

File Transfer Protocol or FTP and Trivial File Transfer Protocol or TFTP are both optimized for uploading and downloading data. FTP makes use of TCP as the transport protocol on port 21 for control (commands) and on port 20 for data transmits. TFTP makes use of UDP on port 69. One of the major disparities between TFTP and FTP is speed.

Because UDP doesn’t carry out issue checking or correction, TFTP is quicker than FTP. File Transfer Protocol offers a generic way of transferring files. It can comprise security through passwords and usernames, and it permits file transfer between dissimilar PC systems. FTP can transmit both text and binary files, comprising HTML, to another host.

FTP URLs are started by ftp:// followed by the FTP server’s DNS name. for signing in to the FTP server, make use of: ftp://username@servername. Trivial File Transfer Protocol is similar to FTP. It allows us to transmit files between an FTP server and a host. However, it offers no error detection and no user authentication. TFTP is frequently utilized when transferring files like audio, video, or pictures.

Because it doesn’t carry out error detection, TFTP is quicker than FTP but may be subject to file issues. One other file transfer protocol that we must know about is SFTP. The S in here stands for Secure. So we have SFTP or Secure File Transfer Protocol.

This protocol makes use of another protocol known as SSH for offering user authentication and encryption of data. SSH makes sure that SFTP transmissions make use of the encrypted commands and data that avert data from being transmitted over a network in a clear text. Secure File Transfer Protocol makes use of TCP on port 115as the transport protocol.

• POP, SMTP & IMAP:

Another protocol set that we will discuss are the email transfer protocols. The first one is SMTP or the Simple Mail Transport Protocol. It is utilized between email clients and servers on each end that have to send mail. It is utilized by email clients for sending mail to the mail server. Then it is utilized between the mail servers for sending mail from one server to the other.

SMTP makes use of TCP transport protocol on port 25. In the end, a diverse protocol might be utilized by the client for downloading or receiving the mail. For instance, the client can make use of a protocol known as POP or Post Office Protocol, or POP3, which is the 3rd version of POP. With a few email client programs, like MS Outlook, SMTP can be utilized for receiving mail from the Exchange server.

POP3 is utilized for retrieving email from a remote server to the local client over the TCP/IP connection. With POP3, email messages are actually downloaded to a client. Remember, the email client that makes use of POP3 to receive mail makes use of SMTP to send mail. POP3 makes use of TCP on port 110 as the transport protocol. Another protocol utilized by clients for downloading email is IMAP.

There are different versions of IMAP, IMAP4 being the most recent one. IMAP can actually support both off-line and on-line modes of operation. Email clients utilizing IMAP usually leave messages on a server until the user explicitly removes them. This one and other IMAP operation characteristics permit multiple email clients to manage the same mailbox.

IMAP provides access to the mail store that denotes that with IMAP, mail stays on a server, so as we read the mail, it is not copied to any local system. Clients might save local copies of the messages, but such is contemplated to be the temporary cache. Remember, the email client that makes use of IMAP to receive mail makes use of SMTP to send mail. IMAP makes use of TCP on port 143 as the transport protocol.

• DHCP:

Another renowned protocol is Dynamic Host Configuration Protocol or DHCP. It is a way of automatically allocating addresses and other configuration parameters to the network hosts. Utilizing the DHCP server, hosts get configuration information at startup, decreasing the amount of manual configuration needed on every host.

This protocol is vital in environments with a lot of PCs. Without DHCP, we’d need to navigate to every PC for configuring, for instance, an IP address. DHCP makes use of UDP as the transport protocol on ports 68 and67 (the client makes use of its own port 68 as a source port with port 67 as the destination on a server for sending the request to a server).

• DNS:

Another amazing protocol is the Domain Name System or DNS. It is a system that is distributed all over the internetwork for providing an address to name resolution. It permits us to utilize hostnames for identifying PCs instead of utilizing an IP address. For example, www.google.com is a logical name that recognizes a web server.

When we utilize this name, we start the HTTP protocol for reading the information that is on that server. It permits us to utilize logical names like this in place of remembering the IP address for the PC that we have to reach. DNS utilizes UDP and TCP as the transport layers on port 53.

• NTP:

Another protocol is NTP or the Network Time Protocol. It permits devices to synchronize the clocks through the network. It is a way that permits devices to synchronize time, and it takes into effect the lag time between different networks as they try to sync their time. It makes use of UDP on port 123.

• NNTP:

Another protocol is the Network News Transport Protocol or NNTP. This protocol is utilized for reading news messages on the web. It is frequently used with Usenet newsgroups. It utilizes TCP as the transport protocol on port 119.

• LDAP:

Another protocol is the Lightweight Directory Access Protocol or LDAP. It’s utilized for allowing searching and updating of the directory service. The LDAP directory service follows the server/client model. One or more LDAP servers hold the directory data, and the LDAP client connects to the LDAP Server for making a directory service request. LDAP can utilize UDP and TCP as the transport protocol on port 389.

• TELNET, SNMP, & SSH:

Such protocols are utilized for network management. Simple Network Management Protocol or SNMP is a protocol created for managing complex networks. It allows network hosts to exchange status and configuration information. Details can be collected by management software and utilized for monitoring and managing the network.

SNMP permits us to take a central PC and correspond with other devices on a network to learn details about such devices. We can send commands to different devices, tell them to perform things like to shutdown and to start-up, or we can simply monitor such PCs. SNMP is a protocol that allows communication and also information transfer from other PCs.

SNMP makes use of UDP as a transport protocol on port 161. Telnet or Remote Terminal Emulation permits an attached PC to act like the dumb terminal, with data processing happening on the TCP/IP host PC. It offers interactive control of the remote systems and is still extensively utilized for offering connectivity between dissimilar systems.

Telnet can also be utilized for testing services by the usage of HTTP commands. Note that Telnet is actually unencrypted. Telnet makes use of TCP as a transport protocol on port 23. Similar to TELNET is the Secure Shell Protocol or SSH. It permits secure interactive control of the remote systems.

SSH utilizes RSA public-key cryptography for both authentication and connection. It by default utilizes the IDEA algorithm for encryption but is capable of using DES and Blowfish. SSH is an acceptable and secure alternative to Telnet. SSH utilizes TCP as a transport protocol on port 22.

Transport Layer Protocols:

A few of the Transport layer protocols in the TCP/IP model are UDP, TCP, SCTP, DCCP, RIP, RSVP, ECN, and BGP, etc. A transport protocol decides how data is sent through the different devices on a network.

• TCP & UDP:

The most common transport protocols utilized are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). The disparity between these two protocols is that TCP is actually a connection-oriented protocol. That denotes that TCP makes sure that information sent is, in fact, received. TCP detects issues and acknowledges received and sent data.

TCP offers flow control, sequencing of data packets, and issue checking to ensure message delivery. UDP is a connectionless protocol. It is not apprehensive about whether the data gets to its destination. It makes the most competent use of a network. UDP is typically utilized in situations where some level of loss is okay.

It is also utilized when we desire to ensure speed over delivery, for instance, to stream audio or video. UDP is the host-to-host protocol like TCP; however, it doesn’t comprise mechanisms for ensuring accurate and timely delivery. Because it’s less overhead, it provides fast communications, but at the cost of possible data loss or issues.

Network Layer Protocols:

A few of the Network layer protocols are ICMP, IP (IPv4 or IPv6), IGMP, ICMPv6, IPSec, and OSPF, etc. Note that we do not have ports for such protocols.

• ICMP:

The Internet Control Message Protocol or ICMP works closely with IP in offering error and control information by permitting hosts for exchanging packet status information, which assists in moving the packets through the internetwork; the two common management utilities, traceroute and ping, make use of ICMP messages for checking the network connectivity.

ICMP also works with IP for sending notices when destinations are inaccessible, when buffers of devices overflow, the hops packets, and route take through a network, and whether devices can correspond across a network.

For instance, if we PING PC B from PC A, PC A sends out a message that on the whole says something like this, if you are there, please reply. If PC B is turned on and is properly configured, it’ll respond back with a reply. It’s called the Echo Response Pattern.

• IGMP:

The final remarkable protocol is the Internet Group Management Protocol or IGMP. It permits us to take a single message and send it to several hosts throughout a network. In general, most communications that take place are between a single host to the one destination host. This sort of communication is known as unicast.

With multicast, you can easily send a single message out, and that message is repeated to the different devices that have to receive it. IGMP is actually a protocol for describing the host groups. All group members can get broadcast messages meant for the group (known as multicasts). Multicast groups can also be composed of different devices across networks (connected using a router) or within the same network.

Link Layer Protocols:

Protocols included in the Link layer are NDP, ARP/InARP, PPP, Tunnels (L2TP), Media access control (DSL, Ethernet, FDDI, and ISDN), etc. The TCP/IP protocol suite was created for working independently of the physical network architecture. We can make use of a wide variety of architectures with the TCP/IP protocol suite.

Remember:

• A protocol is actually a set of rules and standards for communication between different network hosts. Transmission Control Protocol (TCP) and Internet Protocol (IP) Model is referred to as the TCP/IP because of its most significant protocols: Transmission Control Protocol (TCP) and Internet Protocol (IP).
• HTTP recognizes how the web browser submits a request to a server that holds the site and how a server formats that data for returning it back to the web browser. HTTP makes use of UDP or TCP on port 80.
• HTTPS is a secure structure of HTTP that makes use of SSL for encrypting data before its actually transmitted. HTTPS makes use of TCP on port 443.
• TFTP and FTP are both optimized for uploading and downloading data. FTP makes use of TCP as the transport protocol on port 20 for the data transfer and for control (commands) on port 21. TFTP makes use of UDP on port 69.
• SMTP is utilized by the email clients for sending mail to a mail server. SMTP makes use of TCP on port 25.
• POP3 is utilized for retrieving email from the remote server to a local client. POP3 makes use of TCP on port 110.
• IMAP is another amazing protocol that can be utilized for retrieving mail. IMAP utilizes TCP on port 143.
• DHCP is a way of automatically assigning addresses and different configuration parameters to the network hosts. DHCP makes use of UDP as a transport protocol on ports 67 and 68 (the client utilizes its own port 68 as a source port with port 67 as a destination port on a server for sending the request to a server).
• DNS permits us to make use of the hostnames for identifying PCs in place of utilizing an IP address. DNS utilizes UDP and TCP on port 53.
• NTP permits devices to sync their clocks through the network. It utilizes UDP on port 123.
• NNTP is utilized for reading news messages on the web. NNTP makes use of TCP on port 119.
• LDAP is utilized for allowing updating and searching of the directory service. It can make use of UDP and TCP on port 389.
• SNMP allows network hosts to exchange status and configuration information. SNMP utilizes UDP on port 161.
• Telnet offers interactive control of the remote systems. Telnet utilizes TCP on port 23.
• SSH permits secure interactive control of the remote systems. SSH makes use of TCP on port 22.
• The most common transport protocols utilized are the UDP (User Datagram Protocol) and TCP (Transmission Control Protocol). The disparity between these two is that TCP (Transmission Control Protocol) is a connection-oriented protocol.
• The Internet Control Message Protocol (ICMP) works closely with the IP in offering error and control details by permitting hosts to exchange the packet status details.
• IGMP (Internet Group Management Protocol) permits us to take a single message and send it to several hosts throughout a network.