ssh: Document the option modify_algorithms and a User's Guide chapter

1 files changed, 79 insertions, 1 deletions

diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml
index ea7e975ef5..48553bf503 100644
--- a/lib/ssh/doc/src/ssh.xml
+++ b/lib/ssh/doc/src/ssh.xml
@@ -108,6 +108,9 @@
       
       <tag><c>double_algs() =</c></tag>
       <item><p><c>[{client2serverlist,simple_algs()},{server2client,simple_algs()}] | simple_algs()</c></p></item>
+
+      <tag><c>modify_algs_list() =</c></tag>
+      <item><p><c>list( {append,algs_list()} | {prepend,algs_list()} | {rm,algs_list()} )</c></p></item>
      </taglist>
 </section>
 
@@ -254,7 +257,8 @@
 	    </p>
 	  </item>
 
-	  <tag><c><![CDATA[{preferred_algorithms, algs_list()}]]></c></tag>
+	  <tag><marker id="option_preferred_algorithms"></marker>
+	  <c><![CDATA[{preferred_algorithms, algs_list()}]]></c></tag>
 	  <item>
             <p>List of algorithms to use in the algorithm negotiation. The default <c>algs_list()</c> can
 	    be obtained from <seealso marker="#default_algorithms/0">default_algorithms/0</seealso>.
@@ -275,6 +279,8 @@
 	for cipher but specifies the same algorithms for mac and compression in both directions.
 	The kex (key exchange) is implicit but public_key is set explicitly.</p>
 
+	<p>For background and more examples see the <seealso marker="configure_algos#introduction">User's Guide</seealso>.</p>
+
         <warning>
 	  <p>Changing the values can make a connection less secure. Do not change unless you
 	  know exactly what you are doing. If you do not understand the values then you
@@ -282,6 +288,41 @@
 	</warning>
 	  </item>
 
+	  <tag><marker id="option_modify_algorithms"></marker>
+	  <c><![CDATA[{modify_algorithms, modify_algs_list()}]]></c></tag>
+	  <item>
+	    <p>Modifies the list of algorithms to use in the algorithm negotiation. The modifications are
+	    applied after the option <c>preferred_algorithms</c> is applied (if existing)</p>
+	    <p>The possible modifications are to:</p>
+	    <list>
+	      <item><p>Append or prepend supported but not enabled algorithm(s) to the list of
+	      algorithms.</p><p>If the wanted algorithms already are in the list of algorithms, they will first
+	      be removed and then appended or prepended.
+	    </p>
+	      </item>
+	      <item><p>Remove (rm) one or more algorithms from the list of algorithms.</p></item>
+	    </list>
+	    <p>If an unsupported algorithm is in the list, it will be silently ignored</p>
+
+	    <p>Here is an example of this option:</p>
+	<code>
+{modify_algorithms, 
+ [{prepend, [{kex, ['diffie-hellman-group1-sha1']}],
+  {rm,      [{compression, [none]}]}
+ ]
+}
+</code>
+          <p>The example specifies that:</p>
+	  <list>
+	    <item><p>the old key exchange algorithm 'diffie-hellman-group1-sha1' should be
+	    the main alternative. It will be the main alternative since it is prepened to the list</p>
+	    </item>
+	    <item><p>The compression algorithm none (= no compression) is removed so compression is enforced</p>
+	    </item>
+	  </list>
+	  <p>For background and more examples see the <seealso marker="configure_algos#introduction">User's Guide</seealso>.</p>
+	  </item>
+
 	  <tag><c><![CDATA[{dh_gex_limits,{Min=integer(),I=integer(),Max=integer()}}]]></c></tag>
 	  <item>
 	    <p>Sets the three diffie-hellman-group-exchange parameters that guides the connected server in choosing a group.
@@ -555,6 +596,8 @@
 	for cipher but specifies the same algorithms for mac and compression in both directions.
 	The kex (key exchange) is implicit but public_key is set explicitly.</p>
 
+	<p>For background and more examples see the <seealso marker="configure_algos#introduction">User's Guide</seealso>.</p>
+
         <warning>
 	  <p>Changing the values can make a connection less secure. Do not change unless you
 	  know exactly what you are doing. If you do not understand the values then you
@@ -562,6 +605,41 @@
 	</warning>
 	  </item>
 
+	  <tag><marker id="option_modify_algorithms"></marker>
+	  <c><![CDATA[{modify_algorithms, modify_algs_list()}]]></c></tag>
+	  <item>
+	    <p>Modifies the list of algorithms to use in the algorithm negotiation. The modifications are
+	    applied after the option <c>preferred_algorithms</c> is applied (if existing)</p>
+	    <p>The possible modifications are to:</p>
+	    <list>
+	      <item><p>Append or prepend supported but not enabled algorithm(s) to the list of
+	      algorithms.</p><p>If the wanted algorithms already are in the list of algorithms, they will first
+	      be removed and then appended or prepended.
+	    </p>
+	      </item>
+	      <item><p>Remove (rm) one or more algorithms from the list of algorithms.</p></item>
+	    </list>
+	    <p>If an unsupported algorithm is in the list, it will be silently ignored</p>
+
+	    <p>Here is an example of this option:</p>
+	<code>
+{modify_algorithms, 
+ [{prepend, [{kex, ['diffie-hellman-group1-sha1']}],
+  {rm,      [{compression, [none]}]}
+ ]
+}
+</code>
+          <p>The example specifies that:</p>
+	  <list>
+	    <item><p>the old key exchange algorithm 'diffie-hellman-group1-sha1' should be
+	    the main alternative. It will be the main alternative since it is prepened to the list</p>
+	    </item>
+	    <item><p>The compression algorithm none (= no compression) is removed so compression is enforced</p>
+	    </item>
+	  </list>
+	  <p>For background and more examples see the <seealso marker="configure_algos#introduction">User's Guide</seealso>.</p>
+	  </item>
+
 	  <tag><c><![CDATA[{dh_gex_groups, [{Size=integer(),G=integer(),P=integer()}] | {file,filename()} {ssh_moduli_file,filename()} }]]></c></tag>
 	  <item>
 	    <p>Defines the groups the server may choose among when diffie-hellman-group-exchange is negotiated.