Tuesday, July 22, 2014

Proxy Servers


It meas the authority to represent some one else. Here in computer network  proxy is a computer/ software which acts as intermediate between client  and  the server  they  wants to connect.
There are some advantages on this

1. Hide the identity of servers
2. Security filtering
3. Caching which speed up the response to client
4. Can host multiple services in a single IP

There are 2 types of proxies

1. Forward proxy

This is mostly we are referring as proxy. This kind of proxy we are mostly using for sharing Internet connection. That is a clients in a common network can communicate to external network( like Internet)  through this proxy.The proxy is communicating to the external network behalf of clients.

There are so many proxy softwares for this purpose. Squid Proxy server is one of the major software using in Linux for this purpose. You can do settings for caching , content filtering and security configurations in this.

2. Reverse Proxy

This is just opposite to the forward proxy. This kind of proxy settings is used in server side network. Suppose there is a network of multiple servers in data center and there is only one public IP for that network  for clients to connect. Then this reverse proxy in public IP will accept service requests behalf of each servers then redirect that request to corresponding servers and sending back response of requests to respective client.

Both of these proxies give a single point of administration so that we can control the traffic and security parameters in proxy server level.

Apache as proxy

Apache is a web server which can be use in  both Linux and windows platform. We can use apache as proxy server by adding its proxy modules.

LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so

Forward Proxy

ProxyRequests On
This is the parameter for enabling the proxy in apache.

Reverse Proxy

ProxyPass /example http://server1.example.com/example
ProxyPassReverse /example http://server1.example.com/example

This is the sample parameter to enable a proxy in apache. Let us assume www.my-webiste.com is the domain name which mapped in the proxy server( forward) . So if you access www.my-webiste.com/example then the proxy server will receive your request and send it to the http://server1.example.com/example  server and send back the response to the client.So there is no direct interaction between client and server1.

This is page is only to give a basic idea about proxy. I will be posting one more page on apache proxy configuration.

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