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Introduction
The topic discussed in this article in relation to computer networks are addressing and routing will be covered.
Routing
A route defines a path for sending packets through the Internet network to an address on another network. The router is responsible for the routing of traffic between networks. Routers are specialised computers containing the following required components to operate:
· Central processing unit (CPU)
· Operating system (OS) - Routers use Cisco IOS
· Memory and storage (RAM, ROM, NVRAM, Flash, hard drive)
Routers use specialised ports and network interface cards to interconnect to other networks.
Routers can connect multiple networks. Routers have multiple interfaces, each on a different IP network.
Routers use static routes and dynamic routing protocols to learn about remote networks and build their routing tables. Routers use routing tables to determine the best path to send packets. Routers encapsulate the packet and forward it to the interface indicated in routing table.
Process switching – An older packet forwarding mechanism still available for Cisco routers.
Fast switching – A common packet forwarding mechanism which uses a fast-switching cache to store next hop information.
Cisco Express Forwarding (CEF) – The most recent, fastest, and preferred Cisco IOS packet-forwarding mechanism. Table entries are not packet-triggered like fast switching but change-triggered.
There are however, risks to routing to a computer network. Router attacks cannot be 100% prevented, but there are a few things that you can be doing to prevent one of the most common router attacks from occurring on your network. Large organisations are vulnerable to widespread attacks, with some being malicious and some carried out to prove a point. A lot of hackers enjoy breaking a server or router simply because they get a buzz from proving that they’re good enough to do it. Some of the most common router attacks generally include:
· Denial of Service (DOS)
· Packet Mistreating Attacks (PMA)
· Routing Table Poisoning (RTP)
· Hit and Run (HAR)
· Persistent Attacks (PA)
A DoS attack is a very common technique used by hackers to disrupt an entire network and router. They don’t attempt to break system security. They attempt to make your website and servers unavailable to legitimate users, by swamping a system with fake requests – usually in an attempt to exhaust server resources. A DoS attack will involve a single internet connection
Distributed denial of service (DDoS) attacks are launched from multiple connected devices that are distributed across the internet. These multi-person, multi-device attacks target the network infrastructure in an attempt to saturate it with huge volumes of traffic.
A Packet Mistreating Attack (PMA) is the second most common router attack comes in the form of packet mistreating. Packet mistreating injects packets with malicious codes designed to confuse and disrupt the router and network. The data packets mistreat the router, as a result, the router begins to mistreat the harmful packages within the system. Every router has something called a routing process. The introduction of these harmful packages within the routing process means that the router can no longer handle the number of packets currently on the routing table. As the routers become more and more confused, its vulnerability becomes really exposed as the malicious data starts to circulate around the network creating a loop. This proceeds to causing major congestion on the network and makes it extremely difficult for any networking team to debug. As part of any data cabling installation, you should ensure that the routers and networks are secure and provide ongoing testing to prevent such attacks.
Each router has something called a routing table that transfers and receives information. Without the correct protection and encryption, the routing table can become extremely vulnerable. Routing table poisoning occurs when there is a drastic malicious change in the routing table’s routine. These aggressive attacks are achieved by editing the information packets that are cycled through the routing table. Routing poisoning can cause extremely harmful damage to networks and servers as a result of the incorrect data being added to the routing table.
A technique designed as one off attack on a specific network or router. Hit and run attacks are often referred to as ‘test hacks’ and also occur when malicious data is injected into router through code. Usually if an attacker fails at their first attempt, they may, or may not progress and make further attempts on the system. Hit and run router attacks are easier to spot, as the router that is under attack will usually begin displaying unusual activities outside of its usual routine. Networking professionals can then act on the hack and secure the systems. However, if an attack does go unnoticed, a hit and run attack can cause serious damage to the router.
Persistent router attacks are very similar to hit and run, in which they both look to inject frequent harmful data packages into the router and network, helping the hackers gain control. However, unlike the hit and run attacks that we previously discussed, the persistent attacks are exactly as they sound. Whereas the hit and run attacks would start and finish as a one off, the persistent attacks can occur and continue to occur until the attacker has achieved their goal. The attackers will continue to inject harmful packets into the routing table, so it is easy to confuse a persistent attack with a routing table poisoning attacker. The overall aim of persistent router attacks is to attack the networks vulnerabilities and expose them.
Addressing
A data packet contains sender’s and receiver’s address. Each device in the network is assigned a unique address, which is called an IP address. IP addresses consist of binary numbers and are usually represented in decimal or hexadecimal format.
In order for computers to talk to one another, each one must have a unique address, known as an IP address (Internet Protocol address). An IP address is made up of a set of four numbers of up to three digits, ranging from 0 to 254, such as 192.168.0.1. When data is transmitted over a network, the IP address of both the sender and the receiver must be included. The destination IP address is needed to ensure that each packet can be routed to the correct destination. The source IP address must be included so that information can be sent back. Most networking communication takes the form of a request and a response, so without the source IP the response could not be sent back to the correct destination.
In IPv4 (Internet Protocol version 4), each device is assigned a 32-bit address. For example: 197.154.13.145. With 32 bits, around 4 billion unique IP addresses can be assigned. 8 bits form an octet. Each octet may represent any number between 0 and 255. Highest IP we can get is 255.255.255.255.
In IPv6 (Internet Protocol version 6), each device is assigned a 128-bit address. For example: 2001: db8: ac10: fa03: 1528: 11: 134: 2. IPv6 uses 16 bytes per address rather than four and gives a maximum IP address range of 2128 = 3.4 × 1038. This may seem like an obvious solution, but the problem is that devices that use version 4 do not work with version 6. A lot of the Internet’s infrastructure would have to be replaced, which is very difficult as no one person or organisation owns the internet or has influence over each router. Version 6 rollout is very slow.
Static IP addresses are assigned by the network administrator. When the device is not in use, this address remains unused too.
An IP address can be reused when the device is not in use. The protocol responsible for this is dynamic host control protocol (DHCP). Most devices connected to the internet do not have a static address, but a dynamic one. When a device connects to the internet, an IP address is assigned to it by the internet service provider (ISP). ISPs have a set of addresses assigned to them, which they use for their clients. A request is sent to a DHCP (dynamic host configuration protocol) server, which assigns an IP address. By issuing IP addresses on demand, they can be recycled.
Closing Remarks
Routing and addressing are just two huge topics, which was why I wrote a separate article dealing with these two topics. It gives you an idea as to how huge computer networks is as a topic.
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