Github user necouchman commented on a diff in the pull request:
https://github.com/apache/guacamole-manual/pull/91#discussion_r203451449
--- Diff: src/chapters/reverse-proxy.xml ---
@@ -45,6 +45,99 @@
you will be creating connections that have Cyrillic, Chinese,
Japanese, or other
non-Latin characters in their names or parameter values, this
attribute is
required.</para>
+ <section xml:id="tomcat-remote-ip">
+ <title>Setting up the Remote IP Valve</title>
+ <para>By default, when Tomcat is behind a reverse proxy, the
remote IP address of the
+ client that it sees is that of the proxy rather than the
original client. In order
+ to allow applications hosted within Tomcat, like
Guacmaole, to see the actual IP
+ address of the client, you have to configure both the
reverse proxy and Tomcat.</para>
+ <para>Because the remote IP address in Guacamole is used for
auditing of user logins and
+ connections and could potentially be used for
authentication, it is important that you
+ are either in direct control of the proxy server or you
explicitly trust it. Passing
+ the remote IP address is done using the
<code>X-Forwarded-For</code> header, and,
+ as with most HTTP headers, attackers can attempt to spoof
this header in order to
+ manipulate the behavior of the web server, gain
unauthorized access to the system,
+ or attempt to disguise the host or IP address they are
coming from.</para>
+ <para>One final caveat: This may not work as expected if there
are other upstream proxy
+ servers between your reverse proxy and the clients access
Guacamole. Other proxies
+ or firewalls can mask the IP address of the client, and if
the configuration of
+ those is not within your control you may end up with
multiple clients appearing to
+ come from the same IP address or host. Make sure you take
this into account when
+ configuring the system and looking at the data
provided.</para>
+ <para>Configuring Tomcat to pass through the remote IP address
provided by the reverse
+ proxy in the <code>X-Forwarded-For</code> header requires
the configuration of what
+ Tomcat calls a Valve. In this case, it is the
<code>RemoteIpValve</code> and is
--- End diff --
Linked.
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