Sidewinder G2 6.1.2 Administration Guide - Glossary of Technical ...

Figure 123: Port
redirection for inbound
proxy
Port redirection
Chapter 9: Configuring Proxies
Redirected proxy connections
If you need to work around site-specific idiosyncrasies or to obscure the
existence of a proxy for a given service, you can use port redirection. While
such obscurity does not lessen the vulnerability resulting from something like
an inbound Telnet proxy, it does reduce the number of attacks because the
casual attacker might not notice it. Also, the attacker must take more
conspicuous actions, like port scanning, to find the entry point. This makes it
more likely that the administrator will notice the attack. Port redirection is
implemented in the Source/Dest tab of the Rule window on a per-rule basis.
See Chapter 8 for information on configuring port redirection.
As an example, in Figure 123, suppose you want to configure a new proxy for
an internal host that will provide Telnet service and accept external
connections. In this configuration, a proxy connection arrives from the external
network and connects to the external side of the Sidewinder G2. The
connection arrives on the port named “hidenet” (port 5111). When this
connection comes in, it will be proxied to the internal network, similar to how an
address redirection is handled.
Telnet server
192.55.4.4
Telnet port 23
internal
network
redirect
external
network
192.55.214.24
Sidewinder G2
hidenet port 5111
client Telnets to
port 5111 on the
Sidewinder G2
172.16.4.4
The proxy redirects (remaps) the
Telnet session to port 23 (but the
port is concealed from the
external network)
The difference here is that the client on the external network connects to port
5111 (hidenet) on the Sidewinder G2 and the Sidewinder G2 connects the
client to port 23 (the standard Telnet port) on 192.55.4.4 host in the internal
network. This permits an inbound Telnet connection to a host with a private IP
address and does so on a port number that is not well-known for this service.
This discourages so-called “door-knob rattlers.”
249