Land rapid7#9069, Add docs for scanner/http/open_proxy

Author: wwebb-r7

documentation/modules/auxiliary/scanner/http/open_proxy.md

@@ -0,0 +1,52 @@
+## Description
+
+Checks if an HTTP proxy is open. False positives are avoided by verifying the HTTP return code and matching a pattern. The CONNECT method is verified only by the return code. HTTP headers are shown regarding the use of proxies or load balancers.
+
+## Verification Steps
+
+1. Do: ```use auxiliary/scanner/http/open_proxy```
+2. Do: ```set RHOSTS [IP]```
+3. Do: ```set RPORT [PORT]```
+4. Do: ```run```
+
+## Scenarios
+
+### Running the scanner :
+
+```
+msf > use auxiliary/scanner/http/open_proxy 
+msf auxiliary(open_proxy) > show options
+
+Module options (auxiliary/scanner/http/open_proxy):
+
+   Name           Current Setting           Required  Description
+   ----           ---------------           --------  -----------
+   CHECKURL       http://www.google.com     yes       The web site to test via alleged web proxy
+   MULTIPORTS     false                     no        Multiple ports will be used: 80, 443, 1080, 3128, 8000, 8080, 8123
+   Proxies                                  no        A proxy chain of format type:host:port[,type:host:port][...]
+   RHOSTS                                   yes       The target address range or CIDR identifier
+   RPORT          8080                      yes       The target port (TCP)
+   SSL            false                     no        Negotiate SSL/TLS for outgoing connections
+   THREADS        1                         yes       The number of concurrent threads
+   VALIDCODES     200,302                   yes       Valid HTTP code for a successfully request
+   VALIDPATTERN   <TITLE>302 Moved</TITLE>  yes       Valid pattern match (case-sensitive into the headers and HTML body) for a successfully request
+   VERIFYCONNECT  false                     no        Enable CONNECT HTTP method check
+   VHOST                                    no        HTTP server virtual host
+
+msf auxiliary(open_proxy) > set RHOSTS 192.168.1.200-210
+RHOSTS => 192.168.1.200-210
+msf auxiliary(open_proxy) > set RPORT 8888
+RPORT => 8888
+msf auxiliary(open_proxy) > set THREADS 11
+THREADS => 11
+msf auxiliary(open_proxy) > run
+
+[*] 192.168.1.201:8888 is a potentially OPEN proxy [200] (n/a)
+[*] Scanned 02 of 11 hosts (018% complete)
+[*] Scanned 03 of 11 hosts (027% complete)
+[*] Scanned 04 of 11 hosts (036% complete)
+[*] Scanned 05 of 11 hosts (045% complete)
+[*] Scanned 11 of 11 hosts (100% complete)
+[*] Auxiliary module execution completed
+msf auxiliary(open_proxy) >
+```