What is a Hub?
Hubs were the common network infrastructure devices used for LAN connectivity but switches are rapidly replacing hubs. Hubs function as the central connection point for LANs. Hubs are designed to work with Twisted pair cabling and normally use RJ45 jack to connect the devices. Network devices (Servers, Workstations, Printers, Scanners etc) are attached to the hub by individual network cables. Hubs usually come in different shapes and different numbers of ports.
When a hub receives a packet of data (an Ethernet frame) at one of its ports from a network device, it transmits (repeats) the packet to all of its ports to all of the other network devices. If two network devices on the same network try to send packets at the same time a collision is said to occur.
Hubs operate in such a way that all data received through one port is sent to all other ports. This type of operation creates an extremely unsecure environment and anyone can sniff the network using a sniffer and any unencrypted traffic over the network is not secure.
Hubs are unsecure LAN devices that should be replaced with switches for security and increased bandwidth.
Hubs are considered to operate at Physical Layer (Layer 1) of OSI model. An 8 port hub is shown below.