Thursday, March 25, 2010

ASDF

Engaging and interesting opening sentence. A WAN is hard to differentiate from a LAN since they're both based on the size and distance of the network. The book says that a WAN is a network than spans great distances and use phone providers for communication within the WAN. There are 3 different WAN connection types.

Leased Line is a point-to-point connection. It is a permanent line over a long distance.

Circuit Switching is used for telephones and can be used for data as in dial-up. You only pay for the time you use not the data since you have to open up a connection.

Packet Switching
is like a LAN where data sent over a half-duplex connection only one person is sending data at once. Packet Switching is basically on a large scale, so data is sent in bursts. It's not that good since you usually share it with other companies and if you need continuous connection it won't do you any good at all.

So have a happy spring break blah blah gonna go to sleep.


Wednesday, March 24, 2010

Proxies

Not the kind for surfing porn (Henry) on the school network but it's somewhat like that. A proxy server handles all packets moving out of the network. They can dissect a packet which allows you to filter what packets move in and out of the network based on keywords and can even scan for viruses although the more thorough the slower the network will be. Proxies can also hide the I.P.s of computers within the network so hackers can't target a specific machine.

An HTTP proxy is the kind we all know and love. The way it works is a client is configured to sent all HTTP requests to the proxy so when a client accesses a website the request is sent to the proxy and then returns the website to the original sender. This can be useful when you need to get around restrictions like region or network based. An HTTP proxy can also be configured to cache web pages so bandwith isn't wasted on frequently requests web pages. Pretty much everything said applies to any kind of proxy like an FTP proxy.

Monday, March 22, 2010

Network Security

Firewalls. Firewalls basic function is to allow or deny packets based on security restrictions. They can be a combination of software and hardware. A router usually has a firewall but you can also have a machine running as a firewall exclusively known as a network-based firewall. A host-based firewall runs on each machine protecting only that machine (although I guess it could protect from outbound attacks). An ACL is literally what it's called an, an Access Control List. It allows you to control what kind of packets move around inbound and outbound based on conditions specified like in programming. And lastly DMZ. A Demilitarized Zone is a subnet where you store all non critical information behind a firewall. An example is you have a website for ducks. You have your webserver in the DMZ where people can get access to your website and all things duck related but you keep your corporate servers in another subnet with a stricter restrictions.