PORTS
PORTS - In TCP/IP and UDP networks, a port is an endpoint to a logical connection and the way a client program specifies a specific server program on a computer in a network.
Some ports have numbers that are pre-assigned to them by the IANA (Internet Assigned Numbers Authority), and these are known as well-known ports (specified in RFC 1700).
Port numbers range from 0 to 65536, but only ports numbers 0 to 1024 are reserved for privileged services and designated as well-known ports. This list of well-known port numbers specifies the port used by the server process as its contact port.
WELL KNOWN PORT Numbers
20/21 FTP
22 SSH
23 Telnet
25 SMTP
53 DNS
67/68 BOOTP
69 TFTP
80 HTTP
88 Kerberos
110 POP3
119 NNTP
123 NTP
143 IMAP
161 SNMP
389 LDAP
443 SSL
546/547 DHCP
1512 WINS
1701 L2TP
1723 PPTP
1812/13 RADIUS
3389 RDP
If you have any questions about computer ports email me at jescotal@microtrain.net
Jo Blitz Escotal
CEO
Escotal.com
The 7 Layers of the OSI Model
The OSI, or Open System Interconnection, model defines a networking framework for implementing protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, and proceeding to the bottom layer, over the channel to the next station and back up the hierarchy.
Application (Layer 7) this layer supports application and end-user processes. Communication partners are identified, quality of service is identified, user authentication and privacy are considered, and any constraints on data syntax are identified. Everything at this layer is application-specific. This layer provides application services for file transfers, e-mail, and other network software services.
Presentation (Layer 6) this layer provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer.
Session (Layer 5) this layer establishes, manages and terminates connections between applications. The session layer sets up, coordinates, and terminates conversations, exchanges, and dialogues between the applications at each end. It deals with session and connection coordination.
Transport (Layer 4) this layer provides transparent transfer of data between end systems, or hosts, and is responsible for end-to-end error recovery and flow control. It ensures complete data transfer.
Network (Layer 3) this layer provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node. Routing and forwarding are functions of this layer, as well as addressing, internetworking, error handling, congestion control and packet sequencing.
Data Link (Layer 2) at this layer, data packets are encoded and decoded into bits. It furnishes transmission protocol knowledge and management and handles errors in the physical layer, flow control and frame synchronization. The data link layer is divided into two sub layers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC sub layer controls how a computer on the network gains access to the data and permission to transmit it. The LLC layer controls frame synchronization, flow control and error checking.
Physical (Layer 1) this layer conveys the bit stream - electrical impulse, light or radio signal -- through the network at the electrical and mechanical level. It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects.
Jo Blitz Escotal
CEO
Escotal.com
