Ethernet is the most widely used local area network (LAN) technology, that defines wiring and signaling standards for the physical layer of TCP/IP. Ethernet was originally standardized as IEEE 802.3 with a data transmission rate of 10 Mb/s. Newer versions of Ethernet were introduced lately to offer higher data rates. Fast Ethernet and Gigabit Ethernet support data rates of 100 Mbps and 1 Gbps (1000 Mbps) respectively. An Ethernet LAN may use coaxial cable (10Base2), unshielded twisted pair wiring (10BaseT, 100BaseT and 1000BaseT), or fiber optic cable. Ethernet devices compete for access to the network using a protocol called Carrier Sense Multiple Access with Collision Detection (CSMA/CD). With the prosperity of Internet, Wi-Fi, the wireless LAN technology standardized by IEEE 802.11, is used in hybrid with Ethernet LAN to offer portability.

Internet Protocol Version 6 (or IPv6) is a successor of IPv4 Address standard developed by IETF, which is designed to solve IPv4 address exhaustion problem. IPv4 uses a 32-bit numbering scheme to represent an IP address, which has an address space of 232 or 4.3 billion. IPv6, on the other hand, uses a 128-bit numbering scheme (2128) which has big enough address space for many decades to come. IPv6 is intended to replace the IPv4, but the introduction of the CIDR (Classless Inter-Domain Routing) allocation scheme in 1993 within the IPv4 prolonged lifespan of IPv4 Addresses. With the anticipation of smartphones, tablets, smart appliances, and other electronic devices joining the Internet every day, IPv4 address space will eventually exhaust. As of May 2014 per Google Statistics, 96% of Internet traffic is IPv4 and only 4% is represented by IPv6. IPv4 and IPv6 are not interoperable by design, so the transition from IPv4 to IPv6 requires a "transition mechanism" such as Stateless IP/ICMP Translation, Transport Relay, 6rd, and other IPv6 transition mechanisms to make them interoperable.

A Virtual Private Network (VPN) is a network technology which extends private network (such as LAN) over a public network such as the Internet. A VPN allows a computer (or a network) to be connected securely as if they are physically wired together. Corporations use VPN to allow remote workers to connect securely to their private network. A VPN is also used to interconnect remote offices with a head office as if they are physically connected.

You have a private or public network with servers and workstations that are assigned static and dynamic IP addresses (either private or public IPs). You assigned them the static IP addresses due to NAT (Network Address Translation) or for public access, and dynamic IP addresses via the DHCP. Even if you kept a good record of those assigned IPs, there are times when you want to find all IP addresses of networked devices. The following procedure may be used to determine IP addresses of networked devices that are connected to your network.

WAP stands for Wireless Application Protocol. This is a well-known and commonly used standardized protocol which defines how wireless communication can take place between mobile devices and a wireless network. This could include devices such as radio transceivers, cell phones, world wide web, newsgroup, instant messaging and any device that can be used for Internet access. Devices which are based on WAP can interoperate as technology advancement happens over time.

A Wi-Fi (also known as WiFi) is a wireless network technology which allows WiFi enabled devices to communicate with each other, and also share the Internet without wired connectivity. Wi-Fi is based on 802.11 IEEE network standard which uses radio frequency signals to transmit data. The distance supported by Wi-Fi network depends on the type of Wi-Fi radio and antenna in use, and whether the environment is open or enclosed within walls and bricks. As the distance between the Wireless Access Point (WAP) and mobile device move farther away, the radio signal weakens and the transmission data rate slows down until the signal is not strong enough to be usable. The performance of Wi-Fi network also varies depending on the type of standard employed by the Wi-Fi devices, namely 802.11 (a), (b), (g), (n) and (ac).

Often times we see a networked printer suddenly stop working and you need to find a static (private) ip address of the printer to diagnose further. How do we find IP address of a networked printer? There are a few different ways to go about finding it.

RJ-45 conductor data cable contains 4 pairs of wires each consists of a solid colored wire and a strip of the same color. There are two wiring standards for RJ-45 wiring: T-568A and T-568B. Although there are 4 pairs of wires, 10BaseT/100BaseT Ethernet uses only 2 pairs: Orange and Green. The other two colors (blue and brown) may be used for a second Ethernet line or for phone connections. The two wiring standards are used to create a cross-over cable (T-568A on one end, and T-568B on the other end), or a straight-through cable (T-568B or T-568A on both ends).

The two methods described below are extracted from the lartc howto. It is included here to provide a complete reference. For latest updates, please view source document.

Denial of service attacks are major nuisance for web hosts, and as a web host you'll have to take every measure to protect your resources from DoS attacks. Our APF, BFD, DDoS and RootKit article describes Linux utilities available to protect from DDoS attack, and also explains installation procedures. This article supplements above article by providing means to control traffic (bandwidth shaping) with Linux "tc" command so that no single machine can waste the entire network bandwidth.