A collection of computers and computing resources connected together to facilitate communication between resources
Establishing network access
1. Have a network interface that connects to your network access point
2. Run your network services
3. Have access to a network-broadcast device
Network interface
Ethernet device (Ethernet card or wireless card)
Network-broadcast devices
Hub
Switch
Router
Gateway
Hub
Broadcasts the message it receives to all devices on the subnet where it operates
Switch
Broadcasts the message it receives to a single device on the subnetwork using a MAC address for addressing
Router
Examines a message's destination IP address and routes the message onto the proper network or subnetwork as the next link in the chain of the communication
Gateway
Connects local area networks of different types together
TCP/IP layers
Network Interface Layer
Internet Layer
Transport Layer
Application Layer
Network Interface Layer
Responsible for placing TCP/IP packets on the network medium and receiving TCP/IP packets off the network medium
Internet Layer protocols
responsible for addressing, packaging, and routing functions
Internet Protocol (IP)
Responsible for IP addressing, routing, and the fragmentation and reassembly of packets
Address ResolutionProtocol (ARP)
Responsible for the resolution of the Internet layer address to the Network Interface layer such as a hardware address
InternetControlMessageProtocol (ICMP)
Responsible for providing diagnostic functions and reporting errors due to the unsuccessful delivery of IP packets
InternetGroupManagementProtocol (IGMP)
Responsible for the management of IP multicast groups
TransportLayerprotocols
responsible for providing the Application layer with session and datagram communication services
Transmission Control Protocol (TCP)
User Datagram Protocol (UDP)
TransmissionControlProtocol (TCP)
Responsible for establishment of a TCP connection, the sequencing and acknowledging of packets sent, and the recovery of packets lost during transmission
UserDatagramProtocol (UDP)
Used when the amount of data to be transferred is small, when the overhead of establishing a TCP connection is not desired, or when the applications or upper layer protocols provide reliable delivery
ApplicationLayerprotocols
allows applications to access the services of the other layers and defines the protocols that applications use to exchange data.
Hypertext Transfer Protocol (HTTP)
File Transfer Protocol (FTP)
Simple Mail Transfer Protocol (SMTP)
Telnet
HypertextTransferProtocol (HTTP)
Used to transfer files that make up the Web pages of the World Wide Web
FileTransferProtocol (FTP)
Used for interactive file transfer
SimpleMailTransferProtocol (SMTP)
Used for the transfer of mail messages and attachments
Telnet
A terminal emulation protocol used for logging on remotely to network hosts
Other TCP/IP protocols
Domain Name System (DNS)
Routing Information Protocol (RIP)
Simple Network Management Protocol (SNMP)
Domain Name System (DNS)
Used to resolve a host name to an IP address
Routing Information Protocol (RIP)
Used by routers to exchange routing information on an IP internetwork
SimpleNetworkManagementProtocol (SNMP)
Used to collect and exchange network management information between a network management console and network devices
Networking commands
ping
traceroute/tracepath
ip
netstat
ftp
wget
ssh
ping
Sends a special network packet called an ICMP ECHO_REQUEST to network hosts
traceroute/tracepath
Prints the route packets trace to a network host
ip
Shows/manipulates routing, devices, policy routing, and tunnels
netstat
Prints network connections, routing tables, interface statistics, masquerade connections, and multicast memberships