updated proxy configuration information

src/site/markdown/data/proxy.md

@@ -9,3 +9,25 @@ to use a proxy to connect to the Internet. See the configuration settings for ea
 
 Note, it may also be possible to use the core [Java proxy](https://docs.oracle.com/javase/8/docs/technotes/guides/net/proxies.html)
 system properties instead of the configuration above.
+
+Certificate Errors
+------------------
+In some cases if you setup a proxy the connection may still fail due to certificate
+errors (see the log file from dependency-check). If you know which cert it's failing 
+on (either your proxy or NVD/CVE) you can either add the certificate itself or the 
+signing chain to your trust store. If you don't have access to modify the system 
+trust store (in $JAVA_HOME/lib/security/cacerts) you can copy it elsewhere and 
+import it using keytool, then specify that trust store on the command line 
+(`mvn -Djavax.net.ssl.trustStore=/path/to/cacerts`) or if you need to always 
+have that set, you can set the environment variable `JAVA_TOOL_OPTIONS` to have 
+`-Djavax.net.ssl.trustStore=/path/to/cacerts`.
+
+Still failing?
+--------------
+In some cases the proxy is configured to block `HEAD` requests. While an attempt
+is made by dependency-check to identify this situation it does not appear to be
+100% successful. As such, the last thing to try is to add the property 
+`mvn -Ddownloader.quick.query.timestamp=false`.
+
+If trying the above and it still fails please open a ticket in the 
+[github repo](https://github.com/jeremylong/DependencyCheck/issues).

src/site/markdown/dependency-check-gradle/configuration.md

@@ -34,7 +34,7 @@ dependencyCheck {
 
 Property          | Description                        | Default Value
 ------------------|------------------------------------|------------------
-server            | The proxy server.                  |  
+server            | The proxy server; see the [proxy configuration](../data/proxy.html) page for more information. |  
 port              | The proxy port.                    |  
 username          | Defines the proxy user name.       |  
 password          | Defines the proxy password.        |