Tcp/ip Protocols

Front 1

FTP

Back 1

(File Transfer Protocol) When you connect to an FTP server, that FTP server will have port 21 open. Some type of FTP client software is necessary to connect to the FTP server; this could be done in the command line within the FTP shell or by using a GUI-based application (such as FileZilla).

Front 2

SSH

Back 2

(Secure Shell) enables data to be exchanged between computers on a secured channel. This protocol offers a more secure replacement to FTP and Telnet. The Secure Shell server housing the data you want to access would have port 22 open. There are several other protocols that use SSH as a way of making a secure connection. One of these is Secure FTP (SFTP). Regular FTP can be insecure. SFTP combats this by providing file access over a reliable data stream, generated and protected by SSH.

Front 3

Telnet

Back 3

Short for Telecommunication network, this provides remote access to other hosts using the command-line interface (CLI). It uses port 23 but is an insecure and somewhat deprecated protocol. However, because some companies might still use it to access routers and other hosts, you might see a question about it on the exam.

Front 4

SMTP

Back 4

(Simple Mail Transfer Protocol) sends e-mail. When you send e-mail from home, it goes to an SMTP server (which has inbound port 25 open) at your ISP and is then sent off to its destination. A good way to remember this is by using the mnemonic device Send Mail To People. It is worth noting that another port (587) can be used with SMTP in the case that an ISP or other agency blocks port 25.

Front 5

DNS

Back 5

(Domain Name System) is the group of servers on the Internet that translates domain names to IP addresses. A DNS server has inbound port 53 open by default.

Front 6

HTTP

Back 6

(Hypertext Transfer Protocol) transfers web pages and other web-based material from a web server to your web browser. It is normally done in a compressed format but not in a secured format. Web servers have port 80 open by default.

Front 7

POP3

Back 7

(Post Office Version 3) is used by e-mail clients to retrieve incoming e-mail from a mail server. The POP3 mail server uses port 110.

Front 8

IMAP

Back 8

(Internet Message Access Protocol) is an e-mail protocol that enables messages to remain on the e-mail server so they can be retrieved from any location. IMAP also supports folders, so users can organize their messages as desired. IMAP e-mail servers use inbound port 143 open.

Front 9

SLP

Back 9

(Service Location Protocol) enables computers and other devices to access network services in the LAN without prior configuration. They do this with the aid of a URL; for example, service:printer:lpr:// hostname or service:tftp:// hostname. It works on port 427, and often uses UDP as the transport mechanism, but can also use TCP.

Front 10

HTTPS

Back 10

(Hypertext Transfer Protocol Secure) Secure sends and receives information like HTTP but includes the Transport Layer Security protocol (a successor of the Secure Sockets Layer [SSL] protocol) to encrypt the information, most commonly when making purchases/ payments online or when logging in to a confidential website. The HTTPS server has port 443 open.

Front 11

SMB

Back 11

(Server Message Block) protocol provides access to shared items such as files and printers. These are actual packets that authenticate remote computers through what are known as interprocess communication (IPC) mechanisms. They can communicate directly over TCP using port 445 or by working with the NetBIOS protocol using a port between 137 and 139. This was also referred to as the Common Internet File System (CIFS) protocol.

Front 12

AFP

Back 12

(Apple Filing Protocol) offers file services for Mac computers running OS X allowing for the transfer of files across the network. It uses port 548 (and sometimes 427) for establishing the communication between two systems. Mac computers can also make use of SMB (and other protocols) for making connections to other systems.

Front 13

RDP

Back 13

To facilitate connections to remote computers and allow full remote control, Microsoft uses the Remote Desktop program, which is based off the Remote Desktop Protocol (RDP). This works in three ways. First, users can be given limited access to a remote computer’s applications (such as Word or Excel). Second, administrators can be given full access to a computer so that they can troubleshoot problems from another location. Third, another part of the program known as Remote Assistance allows users to invite a technician to view their desktops in the hopes that the technician can fix any encountered problems. These invitations can be made via e-mail or by Windows Messenger. The RDP port, 3389, is also used by Remote Desktop Services/ Microsoft Terminal Services, which is the server-based companion of Remote Desktop.

Front 14

DHCP

Back 14

(Dynamic Host Configuration Protocol) is used to automatically assign IP addresses to hosts. These hosts could be computers, printers, servers, routers, and so on. In most SOHO networks, a router will use DHCP to assign IP addresses to the client computers. However, your ISP will also use DHCP to assign an IP address to you; usually your router gets this. The DHCP service makes life easier for the network administrator by automatically assigning IP addresses, subnet masks, gateway addresses, DNS servers, and so on, from a central location. If you get your address from a DHCP server, you are getting your address assigned dynamically, and it could change periodically. Computers that do obtain IP addresses from a DHCP server have the advantage of automatically getting new addressing when they are moved to a different network segment. However, some computers require a static address, one that is assigned by the network administrator manually. It is better in many situations for servers and printers to use static addresses so you know exactly what the address is and so it won’t change.

Front 15

SNMP

Back 15

(Simple Network Management Protocol) is used as the standard for managing and monitoring devices on your network. It manages routers, switches, and computers and is often incorporated in software known as a network management system (NMS). The NMS is the main software that controls everything SNMP-based; it is installed on a computer known as a manager. The devices to be monitored are known as managed devices. The NMS installs a small piece of software known as an agent that allows the NMS to monitor those managed devices.

Front 16

LDAP

Back 16

(Lightweight Directory Access Protocol) is used to access and maintain distributed directories of information (such as the kind involved with Microsoft domains). Microsoft refers to this as directory services.