Corkscrew and Transparent Socks
Nowadays HotSpot networks are becoming more and more popular. It is known that WiFi networks are used to connect to the Internet on the whole world as hotspots on coffee shops, restaurants, shopping centres etc. It makes our life so easier, but this resulted in the birth of hacking. Hackers use hotpot networks for intrusions. With hotspot networks hackers were not traceable. This implied the closure of ports and the limited access via hotspot networks only for standard services like HTTP and HTTPS. This procedure has gained popularity in the corporate and small business offices. It is not difficult to implement it. The first solution is the Squid proxy with the ACL rules. Using this tool you can deny or allow some type of traffic. Second solution is firewall.
How to solve the problem? Tunnels!
If the other connections (except the standard services) are blocked by firewall or proxy server it is not possible to use e.g. your favourite instant messenger or VoIP client. The first method to avoid this problem is a tunnelling. It does not require additional software, only SSH client and server outside the limited network. It will be necessary to open the connection on another port (like 8080) and configure your application to use service called SOCKS on localhost. It is possible when SSH port is opened by administrator. However it is highly possible that the SSH port will be blocked when admin does not have a private life and spends all time in work ;) Still it is not a big problem, because you will only have to change SSH configuration.
Also the application called CorkScrew can resolve this kind of problem. It was tested with proxies like Squid, Apache mod’s proxy and JunkBaster. At the beginning you have to install CorkScrew application and the next step is configuration of SSH client. Of course for the connection you have to know IP address of proxy server. It may happen that the proxy server needs some authorization, but then you should configure SSH respectively.
Which solution is the best?
There is no answer to this question. You have to match the solution to the problem. Happily, it is not possible to deny HTTP and HTTPS ports completely. These ports are important for proper operation of every network. However, it is possible that administrator configures ISP to refuse all HTTP and HTTPS traffic and redirect it on different (not standard) ports. Despise appearances this situation is not the deadlock. Only CorcScrew can resolve the problem like that. In order to SSH "climbs over" the proxy server, it should use this not standard port, which is passed directly to the server. Any encrypted connection, by its nature, can not be processed by any program on the way to your destination, including the proxy, which is why we refer again to the dear safe 443.
There are incredibly many ways to bypass security. A professional administrator will be able to detected them. If there is any hole in the network security, it really opens up to outsiders the window on the world.