Proxy chain
A proxy chain is a setup in which a request passes through two or more proxies one after another.
Updated · Prokso editorial team
The program connects to the first proxy, through it to the second, and only the last one goes to the site. The site sees the address of the last proxy in the chain.
A chain is used when a proxy can only be reached through a corporate proxy or when the network allows outbound traffic only through one server.
Each link adds latency and one more point where a failure can occur. That is why long chains are not built without need.
Chains are supported by specific programs, for example Proxifier. For most tasks one proxy is enough.
Example: the office proxy first, then Prokso
In many companies a computer can go online only through the office proxy. In Proxifier such a setup is built as a chain: the first link is the office server, the second is gw.prokso.com with port 823 or 824. The program reaches Prokso through the office, and the site sees the Prokso exit address.
Keep in mind who sees what. The office proxy sees that you connect to gw.prokso.com, and Prokso sees the office's outgoing address, not your computer's.
Authorization and traffic in a chain
If you use an IP whitelist, add the outgoing address of the previous link, the one Prokso actually sees. The address of your home or work computer will not work there. A username and password are simpler in a chain: they do not depend on the route.
Prokso counts only the traffic that passes through it, in both directions as usual. Other links in the chain keep their own accounting, if they have any. UDP does not go through the Prokso link at all.
How to find the broken link
Check the links one by one: first the program through the first proxy only, then, if the network allows, through Prokso only, and only after that the whole chain. This shows right away whether the problem is in the route or in one specific server. Many office proxies allow CONNECT only to port 443 by default, so a connection to port 823 may stop at the first link; in that case ask the administrator to open the Prokso ports.
Delays add up along the chain, so a timeout that is enough for one proxy may be too short for two. Increase it a little before looking for other causes.
FAQ
Does a chain make work more secure?
It makes the setup more complex, but each link sees its own part of the connection. For most tasks one reliable proxy is enough.
Which address does the website see?
The address of the last proxy in the chain.
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