Network (TCP/IP)

TCP/UD`P

Port Forwarding

• port forwarding is set on the router
• it is able to access to internal host from external. Port Number is looks like phone extension number.

DHCP(Will Update Nov 15th)

Proxy

Proxy is a kind of a server or a service that translates traffic between users and the internet networks. Proxy servers act like Firewall, filter traffic and cache data to speed up access. In most case proxy server means Web HTTP proxy server. There have some kinds type of proxy server.

• Forward Proxy

Web Server receives Client request via forward proxy. So Web Server receive HTTP request from Forward Proxy, not from Client. Web Server does not receive Client IP Address. And Client IP Address is hidden by Forward Proxy.

• Reverse Proxy

Reverse Proxy set front of Web Server. Reverse Proxy receive client request and client request does not Web Server directly. It is able to prevent external attacks by hiding applications vulnerabilities.

Hub, Switch, Router

• Hub is not intelligence. it si not able to filter packets.it broud cast to all hosts

• Switch has the mac address infomation -it is able to reduce the network traffice. can detect

• hub and switch are not able to read IP Address.

• Router is able to read IP address and the router is able to forward particular router and is able to connect another networks.

Subnet Mask

・IP Address consists network address and host address, it is able to separate them by subnet mask