Firewalls are often categorized as either network firewalls or host-based firewalls. Intermediate nodes are typically network hardware devices such as routers, gateways, firewalls, or switches. Intermediate nodes are typically network hardware devices such as routers, bridges, gateways, firewalls, or switches. SFP sockets are found in Ethernet switches, routers, firewalls and network interface cards. Its primary purpose is to provide failover redundancy, especially when used with firewalls and routers. Other mitigating techniques involve setting up reverse proxies, firewalls, load balancers or content switches. Most specialized network appliance application firewalls are for web applications. Proxies can also be combined with firewalls. Google Analytics can be blocked by browsers, browser extensions, and firewalls and other means. Before the development of stateful firewalls, firewalls were "stateless". Today, computer security comprises mainly "preventive" measures, like firewalls or an exit procedure. Prior to iptables, ipchains was the predominant software package for creating Linux firewalls. It is capable of traversing network address translators (NATs) and firewalls. A common use of CARP is the creation of a group of redundant firewalls. Juniper also confirmed that its NetScreen firewalls were affected.