Defines protocols for node-to-node application communication and also controls user interface specifications. Consists of a set of services that provide ubiquitous access to all types of networks.
Applications utilize the services to communicate with other devices and remote applications
| Port |
Protocol |
Description |
| 23 |
Telnet |
Terminal Emulation (Telephone network) |
| 21 |
FTP |
Allows file transfers between computers (File Transfer Protocol) |
| 69 |
TFTP |
Have to know what you want and where it is on the server, no directory browsing, no user authentication (Trivial File Transfer Protocol) |
| 2049 |
NFS |
Allows remote file systems to be mounted as local (Network File System) |
| 25 |
SMTP |
Used to send mail between mail servers (Simple Mail Transfer Protocol) |
| 515 |
LPD |
Used for print sharing of network printers with TCP/IP (Line Printer Daemon) |
| 161 |
SNMP |
Collect and manipulates network information (Simple Network Management Protocol) |
| 53 |
DNS |
Resolves FQDN to IP addresses (Domain Name Service) |
| 67 |
BootP |
Used by diskless workstations to receive boot file and other information via TFTP |
| |
DHCP |
Assigns IP addresses to hosts from a pool. Can send IP address, Subnet mask,
Domain Name, Default Gateway, DNS IP, WINS info. (Dynamic Host Configuration Protocol) |