Without network security, many companies and home users alike would be exposed for the world to determine and access. Network security doesn't 100% prevent unauthorized users from entering your network but it does help limit a network's availability from the outside world. Cisco devices have many tools to help monitor preventing security threats. The most common technologies found in Cisco network security are Access Control Lists or just Access Lists (ACLs). When businesses depend on their network to create income, potential security breaches become a huge concern. ACL's are implemented through Cisco IOS Software. ACL's define rules that can be used to stop some packets from flowing from the network. The policies implemented on access-lists are usually employed to limit a specific network or host from accessing another network or host. However ACL's could become more granular by implementing what's called a prolonged access-list. Such a ACL lets you deny or permit traffic based not just on source or destination Internet protocol address, but in addition based on the type data that is being sent. Extended ACL's can examine multiple parts of the packet headers, requiring that the parameters be matched before denying or allowing the traffic. Standard ACL's are easier to configure along with enable you to deny or permit information depending on more specific requirements. Standard Access-Lists only enable you to permit or deny traffic using the source address or network. When coming up with ACL's do not forget that almost always there is an implicit deny statement. This means that in case a packet doesn't match all of your access list statements, it will likely be blocked by default. To around come this you ought to configure the permit any statement on Standard ACL's and the permit any any statement on Extended ACL's. Packets may be filtered in several ways. You are able to filter packets because they enter a router's interface before any routing decision is made. You can also filter packets before they exit an interface, following your routing decision is made. Configured ACL's statements will always be read completely. Therefore if a packet matches a statement before you go through the whole ACL, it stops and makes a forwarding decision based on that statement that it matches. Therefore the most crucial and particular statements needs to be made at the outset of your list and you will create statements beginning probably the most important to the very least critical. More information about switch cisco 2960 you can check this web site. switch cisco 2960