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authorHans Nilsson <[email protected]>2017-09-11 12:12:46 +0200
committerHans Nilsson <[email protected]>2017-09-11 12:12:46 +0200
commite15db73b196b1a38f5ce18684739e2b5dd8bb9b2 (patch)
tree5c8a6ca98415ff6fb7d20bb63eb70e8be325cb36
parentc3030004b983348416795848495a2cdc8304fbcc (diff)
parenteee9dc863a4dc806ee48eea07da08bd87ab0bb0c (diff)
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Merge branch 'maint'
-rw-r--r--lib/mnesia/doc/src/Mnesia_chap2.xmlsrc2
-rw-r--r--lib/ssh/doc/src/Makefile3
-rw-r--r--lib/ssh/doc/src/configure_algos.xml428
-rw-r--r--lib/ssh/doc/src/ssh.xml101
-rw-r--r--lib/ssh/doc/src/ssh_app.xml4
-rw-r--r--lib/ssh/doc/src/usersguide.xml1
-rw-r--r--lib/ssh/src/ssh.erl22
-rw-r--r--lib/ssh/src/ssh_options.erl267
-rw-r--r--lib/ssh/src/ssh_transport.erl19
-rw-r--r--lib/ssh/test/ssh_protocol_SUITE.erl140
10 files changed, 902 insertions, 85 deletions
diff --git a/lib/mnesia/doc/src/Mnesia_chap2.xmlsrc b/lib/mnesia/doc/src/Mnesia_chap2.xmlsrc
index 37389ce5ae..914e0e509c 100644
--- a/lib/mnesia/doc/src/Mnesia_chap2.xmlsrc
+++ b/lib/mnesia/doc/src/Mnesia_chap2.xmlsrc
@@ -327,7 +327,7 @@
<section>
<title>Initial Database Content</title>
<p>After the insertion of the employee named <c>klacke</c>,
- the databse has the following records:</p>
+ the database has the following records:</p>
<marker id="table2_1"></marker>
<table>
<row>
diff --git a/lib/ssh/doc/src/Makefile b/lib/ssh/doc/src/Makefile
index a759854da4..adbda5a030 100644
--- a/lib/ssh/doc/src/Makefile
+++ b/lib/ssh/doc/src/Makefile
@@ -53,7 +53,8 @@ XML_PART_FILES = part_notes.xml \
XML_CHAPTER_FILES = notes.xml \
introduction.xml \
ssh_protocol.xml \
- using_ssh.xml
+ using_ssh.xml \
+ configure_algos.xml
BOOK_FILES = book.xml
diff --git a/lib/ssh/doc/src/configure_algos.xml b/lib/ssh/doc/src/configure_algos.xml
new file mode 100644
index 0000000000..dd60324851
--- /dev/null
+++ b/lib/ssh/doc/src/configure_algos.xml
@@ -0,0 +1,428 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE chapter SYSTEM "chapter.dtd">
+
+<chapter>
+ <header>
+ <copyright>
+ <year>2017</year>
+ <year>2017</year>
+ <holder>Ericsson AB. All Rights Reserved.</holder>
+ </copyright>
+ <legalnotice>
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+ </legalnotice>
+
+ <title>Configuring algorithms in SSH</title>
+ <prepared></prepared>
+ <docno></docno>
+ <approved></approved>
+ <date></date>
+ <rev></rev>
+ <file>configure_algos.xml</file>
+ </header>
+
+ <section>
+ <marker id="introduction"/>
+ <title>Introduction</title>
+ <p>To fully understand how to configure the algorithms, it is essential to have a basic understanding of the SSH protocol
+ and how OTP SSH app handles the corresponding items</p>
+
+ <p>The first subsection will give a short background of the SSH protocol while later sections describes
+ the implementation and provides some examples</p>
+
+ <section>
+ <title>Basics of the ssh protocol's algorithms handling</title>
+
+ <p>SSH uses different sets of algorithms in different phases of a session. Which
+ algorithms to use is negotiated by the client and the server at the beginning of a session.
+ See <url href="https://tools.ietf.org/html/rfc4253">RFC 4253</url>,
+ "The Secure Shell (SSH) Transport Layer Protocol" for details.
+ </p>
+
+ <p>The negotiation is simple: both peers sends their list of supported alghorithms to the other part.
+ The first algorithm on the client's list that also in on the server's list is selected. So it is the
+ client's orderering of the list that gives the priority for the algorithms.</p>
+
+ <p>There are five lists exchanged in the connection setup. Three of them are also divided in two
+ directions, to and from the server.</p>
+
+ <p>The lists are (named as in the SSH application's options):</p>
+ <taglist>
+ <tag><c>kex</c></tag>
+ <item>
+ <p>Key exchange.</p>
+ <p>An algorithm is selected for computing a secret encryption key. Among examples are:
+ the old nowadays week <c>'diffie-hellman-group-exchange-sha1'</c> and the very strong and modern
+ <c>'ecdh-sha2-nistp512'</c>.</p>
+ </item>
+
+ <tag><c>public_key</c></tag>
+ <item>
+ <p>Server host key</p>
+ <p>The asymetric encryption algorithm used in the server's private-public host key pair.
+ Examples include the well-known RSA <c>'ssh-rsa'</c> and elliptic curve <c>'ecdsa-sha2-nistp521'</c>.
+ </p>
+ </item>
+
+ <tag><c>cipher</c></tag>
+ <item>
+ <p>Symetric cipher algorithm used for the payload encryption. This algorithm will use the key calculated
+ in the kex phase (together with other info) to genereate the actual key used. Examples are
+ tripple-DES <c>'3des-cbc'</c> and one of many AES variants <c>'aes192-ctr'</c>.
+ </p>
+ <p>This list is actually two - one for each direction server-to-client and client-to-server. Therefore it
+ is possible but rare to have different algorithms in the two directions in one connection.</p>
+ </item>
+
+ <tag><c>mac</c></tag>
+ <item>
+ <p>Message authentication code</p>
+ <p>"Check sum" of each message sent between the peers. Examples are SHA <c>'hmac-sha1'</c> and
+ SHA2 <c>'hmac-sha2-512'</c>.</p>
+ <p>This list is also divided into two for the both directions</p>
+ </item>
+
+ <tag><c>compression</c></tag>
+ <item>
+ <p>If and how to compress the message. Examples are <c>none</c>, that is, no compression and
+ <c>zlib</c>.</p>
+ <p>This list is also divided into two for the both directions</p>
+ </item>
+
+ </taglist>
+ </section>
+
+ <section>
+ <title>The SSH app's mechanism</title>
+ <p>The set of algorithms that the SSH app uses by default depends on the algoritms supported by the:</p>
+ <list>
+ <item><p><seealso marker="crypto:crypto">crypto</seealso> app,</p>
+ </item>
+ <item><p>The cryptolib OTP is linked with, usally the one the OS uses, probably OpenSSL,</p>
+ </item>
+ <item><p>and finaly what the SSH app implements</p>
+ </item>
+ </list>
+ <p>Due to this, it impossible to list in documentation what algorithms that are available in a certain installation.</p>
+ <p>There is an important command to list the actual algorithms and their ordering:
+ <seealso marker="ssh#default_algorithms-0">ssh:default_algorithms/0</seealso>.</p>
+ <code type="erl">
+0> ssh:default_algorithms().
+[{kex,['ecdh-sha2-nistp384','ecdh-sha2-nistp521',
+ 'ecdh-sha2-nistp256','diffie-hellman-group-exchange-sha256',
+ 'diffie-hellman-group16-sha512',
+ 'diffie-hellman-group18-sha512',
+ 'diffie-hellman-group14-sha256',
+ 'diffie-hellman-group14-sha1',
+ 'diffie-hellman-group-exchange-sha1']},
+ {public_key,['ecdsa-sha2-nistp384','ecdsa-sha2-nistp521',
+ 'ecdsa-sha2-nistp256','ssh-rsa','rsa-sha2-256',
+ 'rsa-sha2-512','ssh-dss']},
+ {cipher,[{client2server,['[email protected]',
+ 'aes256-ctr','aes192-ctr','[email protected]',
+ 'aes128-ctr','aes128-cbc','3des-cbc']},
+ {server2client,['[email protected]','aes256-ctr',
+ 'aes192-ctr','[email protected]','aes128-ctr',
+ 'aes128-cbc','3des-cbc']}]},
+ {mac,[{client2server,['hmac-sha2-256','hmac-sha2-512',
+ 'hmac-sha1']},
+ {server2client,['hmac-sha2-256','hmac-sha2-512',
+ 'hmac-sha1']}]},
+ {compression,[{client2server,[none,'[email protected]',zlib]},
+ {server2client,[none,'[email protected]',zlib]}]}]
+
+ </code>
+ <p>To change the algorithm list, there are two options which can be used in
+ <seealso marker="ssh#connect-3">ssh:connect/2,3,4</seealso>
+ and
+ <seealso marker="ssh#daemon-2">ssh:daemon/2,3</seealso>. The options could of course
+ be used in all other functions that initiates connections.</p>
+
+ <p>The options are <c>preferred_algorithms</c> and <c>modify_algorithms</c>. The first one
+ replaces the default set, while the latter modifies the default set.</p>
+ </section>
+ </section>
+
+ <section>
+ <title>Replacing the default set: preferred_algorithms</title>
+ <p>See the <seealso marker="ssh#option_preferred_algorithms">Reference Manual</seealso> for details</p>
+
+ <p>Here follows a series of examples ranging from simple to more complex.</p>
+
+ <p>To forsee the effect of an option there is an experimental function <c>ssh:chk_algos_opts(Opts)</c>.
+ It mangles the options <c>preferred_algorithms</c>
+ and <c>modify_algorithms</c> in the same way as <c>ssh:dameon</c>, <c>ssh:connect</c> and their friends does.</p>
+
+ <section>
+ <title>Example 1</title>
+ <p>Replace the kex algorithms list with the single algorithm <c>'diffie-hellman-group14-sha256'</c>:</p>
+ <code>
+1> ssh:chk_algos_opts(
+ [{preferred_algorithms,
+ [{kex, ['diffie-hellman-group14-sha256']}
+ ]
+ }
+ ]).
+[{kex,['diffie-hellman-group14-sha256']},
+ {public_key,['ecdsa-sha2-nistp384','ecdsa-sha2-nistp521',
+ 'ecdsa-sha2-nistp256','ssh-rsa','rsa-sha2-256',
+ 'rsa-sha2-512','ssh-dss']},
+ {cipher,[{client2server,['[email protected]',
+ 'aes256-ctr','aes192-ctr','[email protected]',
+ 'aes128-ctr','aes128-cbc','3des-cbc']},
+ {server2client,['[email protected]','aes256-ctr',
+ 'aes192-ctr','[email protected]','aes128-ctr',
+ 'aes128-cbc','3des-cbc']}]},
+ {mac,[{client2server,['hmac-sha2-256','hmac-sha2-512',
+ 'hmac-sha1']},
+ {server2client,['hmac-sha2-256','hmac-sha2-512',
+ 'hmac-sha1']}]},
+ {compression,[{client2server,[none,'[email protected]',zlib]},
+ {server2client,[none,'[email protected]',zlib]}]}]
+ </code>
+ <p>Note that the unmentioned lists (<c>public_key</c>, <c>cipher</c>, <c>mac</c> and <c>compression</c>)
+ are un-changed.</p>
+ </section>
+
+ <section>
+ <title>Example 2</title>
+ <p>In the lists that are divided in two for the two directions (c.f <c>cipher</c>) it is possible
+ to change both directions at once:</p>
+ <code>
+2> ssh:chk_algos_opts(
+ [{preferred_algorithms,
+ [{cipher,['aes128-ctr']}
+ ]
+ }
+ ]).
+[{kex,['ecdh-sha2-nistp384','ecdh-sha2-nistp521',
+ 'ecdh-sha2-nistp256','diffie-hellman-group-exchange-sha256',
+ 'diffie-hellman-group16-sha512',
+ 'diffie-hellman-group18-sha512',
+ 'diffie-hellman-group14-sha256',
+ 'diffie-hellman-group14-sha1',
+ 'diffie-hellman-group-exchange-sha1']},
+ {public_key,['ecdsa-sha2-nistp384','ecdsa-sha2-nistp521',
+ 'ecdsa-sha2-nistp256','ssh-rsa','rsa-sha2-256',
+ 'rsa-sha2-512','ssh-dss']},
+ {cipher,[{client2server,['aes128-ctr']},
+ {server2client,['aes128-ctr']}]},
+ {mac,[{client2server,['hmac-sha2-256','hmac-sha2-512',
+ 'hmac-sha1']},
+ {server2client,['hmac-sha2-256','hmac-sha2-512',
+ 'hmac-sha1']}]},
+ {compression,[{client2server,[none,'[email protected]',zlib]},
+ {server2client,[none,'[email protected]',zlib]}]}]
+ </code>
+ <p>Note that both lists in <c>cipher</c> has been changed to the provided value (<c>'aes128-ctr'</c>).</p>
+ </section>
+
+ <section>
+ <title>Example 3</title>
+ <p>In the lists that are divided in two for the two directions (c.f <c>cipher</c>) it is possible
+ to change only one of the directions:</p>
+ <code>
+3> ssh:chk_algos_opts(
+ [{preferred_algorithms,
+ [{cipher,[{client2server,['aes128-ctr']}]}
+ ]
+ }
+ ]).
+[{kex,['ecdh-sha2-nistp384','ecdh-sha2-nistp521',
+ 'ecdh-sha2-nistp256','diffie-hellman-group-exchange-sha256',
+ 'diffie-hellman-group16-sha512',
+ 'diffie-hellman-group18-sha512',
+ 'diffie-hellman-group14-sha256',
+ 'diffie-hellman-group14-sha1',
+ 'diffie-hellman-group-exchange-sha1']},
+ {public_key,['ecdsa-sha2-nistp384','ecdsa-sha2-nistp521',
+ 'ecdsa-sha2-nistp256','ssh-rsa','rsa-sha2-256',
+ 'rsa-sha2-512','ssh-dss']},
+ {cipher,[{client2server,['aes128-ctr']},
+ {server2client,['[email protected]','aes256-ctr',
+ 'aes192-ctr','[email protected]','aes128-ctr',
+ 'aes128-cbc','3des-cbc']}]},
+ {mac,[{client2server,['hmac-sha2-256','hmac-sha2-512',
+ 'hmac-sha1']},
+ {server2client,['hmac-sha2-256','hmac-sha2-512',
+ 'hmac-sha1']}]},
+ {compression,[{client2server,[none,'[email protected]',zlib]},
+ {server2client,[none,'[email protected]',zlib]}]}]
+ </code>
+ </section>
+
+ <section>
+ <title>Example 4</title>
+ <p>It is of course possible to change more than one list:</p>
+ <code>
+4> ssh:chk_algos_opts(
+ [{preferred_algorithms,
+ [{cipher,['aes128-ctr']},
+ {mac,['hmac-sha2-256']},
+ {kex,['ecdh-sha2-nistp384']},
+ {public_key,['ssh-rsa']},
+ {compression,[{server2client,[none]},
+ {client2server,[zlib]}]}
+ ]
+ }
+ ]).
+[{kex,['ecdh-sha2-nistp384']},
+ {public_key,['ssh-rsa']},
+ {cipher,[{client2server,['aes128-ctr']},
+ {server2client,['aes128-ctr']}]},
+ {mac,[{client2server,['hmac-sha2-256']},
+ {server2client,['hmac-sha2-256']}]},
+ {compression,[{client2server,[zlib]},
+ {server2client,[none]}]}]
+
+ </code>
+ <p>Note that the ordering of the tuples in the lists didn't matter.</p>
+ </section>
+ </section>
+
+ <section>
+ <title>Modifying the default set: modify_algorithms</title>
+ <p>A situation where it might be useful to add an algorithm is when one need to use a supported but disabled one.
+ An example is the <c>'diffie-hellman-group1-sha1'</c> which nowadays is very unsecure and therefore disabled. It is
+ however still supported and might be used.</p>
+
+ <p>The option <c>preferred_algorithms</c> may be complicated to use for adding or removing single algorithms.
+ First one has to list them with <c>ssh:default_algorithms()</c> and then do changes in the lists.</p>
+
+ <p>To facilitate addition or removal of algorithms the option <c>modify_algorithms</c> is available.
+ See the <seealso marker="ssh#option_modify_algorithms">Reference Manual</seealso> for details.</p>
+
+ <p>The option takes a list with instructions to append, prepend or remove algorithms:</p>
+ <code type="erl">
+{modify_algorithms, [{append, ...},
+ {prepend, ...},
+ {rm, ...}
+ ]}
+ </code>
+ <p>Each of the <c>...</c> can be a <c>algs_list()</c> as the argument to the <c>preferred_algorithms</c> option.</p>
+ <section>
+ <title>Example 5</title>
+ <p>As an example let's add the Diffie-Hellman Group1 first in the kex list. It is supported according to
+ <seealso marker="SSH_app#supported_algos">Supported algoritms</seealso>.</p>
+ <code type="erl">
+5> ssh:chk_algos_opts(
+ [{modify_algorithms,
+ [{prepend,
+ [{kex,['diffie-hellman-group1-sha1']}]
+ }
+ ]
+ }
+ ]).
+[{kex,['diffie-hellman-group1-sha1','ecdh-sha2-nistp384',
+ 'ecdh-sha2-nistp521','ecdh-sha2-nistp256',
+ 'diffie-hellman-group-exchange-sha256',
+ 'diffie-hellman-group16-sha512',
+ 'diffie-hellman-group18-sha512',
+ 'diffie-hellman-group14-sha256',
+ 'diffie-hellman-group14-sha1',
+ 'diffie-hellman-group-exchange-sha1']},
+ {public_key,['ecdsa-sha2-nistp384','ecdsa-sha2-nistp521',
+ 'ecdsa-sha2-nistp256','ssh-rsa','rsa-sha2-256',
+ 'rsa-sha2-512','ssh-dss']},
+ {cipher,[{client2server,['[email protected]',
+ 'aes256-ctr','aes192-ctr','[email protected]',
+ 'aes128-ctr','aes128-cbc','3des-cbc']},
+ {server2client,['[email protected]','aes256-ctr',
+ 'aes192-ctr','[email protected]','aes128-ctr',
+ 'aes128-cbc','3des-cbc']}]},
+ {mac,[{client2server,['hmac-sha2-256','hmac-sha2-512',
+ 'hmac-sha1']},
+ {server2client,['hmac-sha2-256','hmac-sha2-512',
+ 'hmac-sha1']}]},
+ {compression,[{client2server,[none,'[email protected]',zlib]},
+ {server2client,[none,'[email protected]',zlib]}]}]
+
+ </code>
+ <p>And the result shows that the Diffie-Hellman Group1 is added at the head of the kex list</p>
+ </section>
+
+ <section>
+ <title>Example 6</title>
+ <p>In this example, we in put the 'diffie-hellman-group1-sha1' first and also move the
+ <c>'ecdh-sha2-nistp521'</c> to the end in the kex list, that is, <c>append</c> it.</p>
+ <code type="erl">
+6> ssh:chk_algos_opts(
+ [{modify_algorithms,
+ [{prepend,
+ [{kex, ['diffie-hellman-group1-sha1']}
+ ]},
+ {append,
+ [{kex, ['ecdh-sha2-nistp521']}
+ ]}
+ ]
+ }
+ ]).
+[{kex,['diffie-hellman-group1-sha1','ecdh-sha2-nistp384',
+ 'ecdh-sha2-nistp256','diffie-hellman-group-exchange-sha256',
+ 'diffie-hellman-group16-sha512',
+ 'diffie-hellman-group18-sha512',
+ 'diffie-hellman-group14-sha256',
+ 'diffie-hellman-group14-sha1',
+ 'diffie-hellman-group-exchange-sha1','ecdh-sha2-nistp521']},
+ {public_key,['ecdsa-sha2-nistp384','ecdsa-sha2-nistp521',
+ .....
+]
+ </code>
+ <p>Note that the appended algorithm is removed from its original place and then appended to the same list.</p>
+ </section>
+
+ <section>
+ <title>Example 7</title>
+ <p>In this example, we use both options (<c>preferred_algorithms</c> and <c>modify_algorithms</c>) and
+ also try to prepend an unsupported algorithm. Any unsupported algorithm is quietly removed.</p>
+ <code type="erl">
+7> ssh:chk_algos_opts(
+ [{preferred_algorithms,
+ [{cipher,['aes128-ctr']},
+ {mac,['hmac-sha2-256']},
+ {kex,['ecdh-sha2-nistp384']},
+ {public_key,['ssh-rsa']},
+ {compression,[{server2client,[none]},
+ {client2server,[zlib]}]}
+ ]
+ },
+ {modify_algorithms,
+ [{prepend,
+ [{kex, ['some unsupported algorithm']}
+ ]},
+ {append,
+ [{kex, ['diffie-hellman-group1-sha1']}
+ ]}
+ ]
+ }
+ ]).
+[{kex,['ecdh-sha2-nistp384','diffie-hellman-group1-sha1']},
+ {public_key,['ssh-rsa']},
+ {cipher,[{client2server,['aes128-ctr']},
+ {server2client,['aes128-ctr']}]},
+ {mac,[{client2server,['hmac-sha2-256']},
+ {server2client,['hmac-sha2-256']}]},
+ {compression,[{client2server,[zlib]},
+ {server2client,[none]}]}]
+
+ </code>
+ <p>It is of course questionable why anyone would like to use the both these options together,
+ but it is possible if an unforeseen need should arise.</p>
+ </section>
+
+
+
+ </section>
+
+</chapter>
diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml
index ea7e975ef5..d9516fff12 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 +288,62 @@
</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> (if existing) is applied.</p>
+ <p>The algoritm for modifications works like this:</p>
+ <list>
+ <item>
+ <p>Input is the <c>modify_algs_list()</c> and a set of algorithms <c>A</c>
+ obtained from the <c>preferred_algorithms</c> option if existing, or else from the
+ <seealso marker="ssh#default_algorithms-0">ssh:default_algorithms/0</seealso>.
+ </p>
+ </item>
+ <item>
+ <p>The head of the <c>modify_algs_list()</c> modifies <c>A</c> giving the result <c>A'</c>.</p>
+ <p>The possible modifications are:</p>
+ <list>
+ <item>
+ <p>Append or prepend supported but not enabled algorithm(s) to the list of
+ algorithms. If the wanted algorithms already are in <c>A</c> they will first
+ be removed and then appended or prepended,
+ </p>
+ </item>
+ <item>
+ <p>Remove (rm) one or more algorithms from <c>A</c>.
+ </p>
+ </item>
+ </list>
+ </item>
+ <item>
+ <p>Repeat the modification step with the tail of <c>modify_algs_list()</c> and the resulting
+ <c>A'</c>.
+ </p>
+ </item>
+ </list>
+ <p>If an unsupported algorithm is in the <c>modify_algs_list()</c>, it will be silently ignored</p>
+ <p>If there are more than one modify_algorithms options, the result is undefined.</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 +617,8 @@
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 +626,41 @@
</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.
diff --git a/lib/ssh/doc/src/ssh_app.xml b/lib/ssh/doc/src/ssh_app.xml
index 33ec7aaee0..1cbbdfcf38 100644
--- a/lib/ssh/doc/src/ssh_app.xml
+++ b/lib/ssh/doc/src/ssh_app.xml
@@ -97,7 +97,7 @@
<p>The <c>known_hosts</c> file contains a list of approved servers and
their public keys. Once a server is listed, it can be verified
without user interaction.
- </p>
+ </p>
</section>
<section>
<title>Authorized Keys</title>
@@ -135,7 +135,7 @@
</p>
<p>Supported algorithms are:</p>
-
+ <marker id="supported_algos"></marker>
<taglist>
<tag>Key exchange algorithms</tag>
<item>
diff --git a/lib/ssh/doc/src/usersguide.xml b/lib/ssh/doc/src/usersguide.xml
index 70051ba771..d902df6848 100644
--- a/lib/ssh/doc/src/usersguide.xml
+++ b/lib/ssh/doc/src/usersguide.xml
@@ -36,4 +36,5 @@
</description>
<xi:include href="introduction.xml"/>
<xi:include href="using_ssh.xml"/>
+ <xi:include href="configure_algos.xml"/>
</part>
diff --git a/lib/ssh/src/ssh.erl b/lib/ssh/src/ssh.erl
index 5ebab43c30..1a5d48baca 100644
--- a/lib/ssh/src/ssh.erl
+++ b/lib/ssh/src/ssh.erl
@@ -35,6 +35,7 @@
daemon/1, daemon/2, daemon/3,
daemon_info/1,
default_algorithms/0,
+ chk_algos_opts/1,
stop_listener/1, stop_listener/2, stop_listener/3,
stop_daemon/1, stop_daemon/2, stop_daemon/3,
shell/1, shell/2, shell/3
@@ -381,6 +382,27 @@ default_algorithms() ->
ssh_transport:default_algorithms().
%%--------------------------------------------------------------------
+-spec chk_algos_opts(list(any())) -> algs_list() .
+%%--------------------------------------------------------------------
+chk_algos_opts(Opts) ->
+ case lists:foldl(
+ fun({preferred_algorithms,_}, Acc) -> Acc;
+ ({modify_algorithms,_}, Acc) -> Acc;
+ (KV, Acc) -> [KV|Acc]
+ end, [], Opts)
+ of
+ [] ->
+ case ssh_options:handle_options(client, Opts) of
+ M when is_map(M) ->
+ maps:get(preferred_algorithms, M);
+ Others ->
+ Others
+ end;
+ OtherOps ->
+ {error, {non_algo_opts_found,OtherOps}}
+ end.
+
+%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
%% The handle_daemon_args/2 function basically only sets the ip-option in Opts
diff --git a/lib/ssh/src/ssh_options.erl b/lib/ssh/src/ssh_options.erl
index b41ad8b33b..6939094401 100644
--- a/lib/ssh/src/ssh_options.erl
+++ b/lib/ssh/src/ssh_options.erl
@@ -170,9 +170,10 @@ handle_options(Role, PropList0, Opts0) when is_map(Opts0),
OptionDefinitions),
%% Enter the user's values into the map; unknown keys are
%% treated as socket options
- lists:foldl(fun(KV, Vals) ->
- save(KV, OptionDefinitions, Vals)
- end, InitialMap, PropList1)
+ final_preferred_algorithms(
+ lists:foldl(fun(KV, Vals) ->
+ save(KV, OptionDefinitions, Vals)
+ end, InitialMap, PropList1))
catch
error:{eoptions, KV, undefined} ->
{error, {eoptions,KV}};
@@ -509,6 +510,15 @@ default(common) ->
class => user_options
},
+ %% NOTE: This option is supposed to be used only in this very module (?MODULE). There is
+ %% a final stage in handle_options that "merges" the preferred_algorithms option and this one.
+ %% The preferred_algorithms is the one to use in the rest of the ssh application!
+ {modify_algorithms, def} =>
+ #{default => undefined, % signals error if unsupported algo in preferred_algorithms :(
+ chk => fun check_modify_algorithms/1,
+ class => user_options
+ },
+
{id_string, def} =>
#{default => undefined, % FIXME: see ssh_transport:ssh_vsn/0
chk => fun(random) ->
@@ -820,83 +830,190 @@ valid_hash(L, Ss) when is_list(L) -> lists:all(fun(S) -> valid_hash(S,Ss) end, L
valid_hash(X, _) -> error_in_check(X, "Expect atom or list in fingerprint spec").
%%%----------------------------------------------------------------
-check_preferred_algorithms(Algs) ->
- [error_in_check(K,"Bad preferred_algorithms key")
- || {K,_} <- Algs,
- not lists:keymember(K,1,ssh:default_algorithms())],
+check_modify_algorithms(M) when is_list(M) ->
+ [error_in_check(Op_KVs, "Bad modify_algorithms")
+ || Op_KVs <- M,
+ not is_tuple(Op_KVs)
+ orelse (size(Op_KVs) =/= 2)
+ orelse (not lists:member(element(1,Op_KVs), [append,prepend,rm]))],
+ {true, [{Op,normalize_mod_algs(KVs,false)} || {Op,KVs} <- M]};
+check_modify_algorithms(_) ->
+ error_in_check(modify_algorithms, "Bad option value. List expected.").
+
+
+
+
+normalize_mod_algs(KVs, UseDefaultAlgs) ->
+ normalize_mod_algs(ssh_transport:algo_classes(), KVs, [], UseDefaultAlgs).
+
+normalize_mod_algs([K|Ks], KVs0, Acc, UseDefaultAlgs) ->
+ %% Pick the expected keys in order and check if they are in the user's list
+ {Vs1, KVs} =
+ case lists:keytake(K, 1, KVs0) of
+ {value, {K,Vs0}, KVs1} ->
+ {Vs0, KVs1};
+ false ->
+ {[], KVs0}
+ end,
+ Vs = normalize_mod_alg_list(K, Vs1, UseDefaultAlgs),
+ normalize_mod_algs(Ks, KVs, [{K,Vs} | Acc], UseDefaultAlgs);
+normalize_mod_algs([], [], Acc, _) ->
+ %% No values left in the key-value list after removing the expected entries
+ %% (thats good)
+ lists:reverse(Acc);
+normalize_mod_algs([], [{K,_}|_], _, _) ->
+ %% Some values left in the key-value list after removing the expected entries
+ %% (thats bad)
+ case ssh_transport:algo_class(K) of
+ true -> error_in_check(K, "Duplicate key");
+ false -> error_in_check(K, "Unknown key")
+ end;
+normalize_mod_algs([], [X|_], _, _) ->
+ error_in_check(X, "Bad list element").
- try alg_duplicates(Algs, [], [])
- of
- [] ->
- {true,
- [case proplists:get_value(Key, Algs) of
- undefined ->
- {Key,DefAlgs};
- Vals ->
- handle_pref_alg(Key,Vals,SupAlgs)
- end
- || {{Key,DefAlgs}, {Key,SupAlgs}} <- lists:zip(ssh:default_algorithms(),
- ssh_transport:supported_algorithms())
- ]
- };
-
- Dups ->
- error_in_check(Dups, "Duplicates")
- catch
- _:_ ->
- false
- end.
-alg_duplicates([{K,V}|KVs], Ks, Dups0) ->
- Dups =
- case lists:member(K,Ks) of
- true -> [K|Dups0];
- false -> Dups0
- end,
- case V--lists:usort(V) of
- [] -> alg_duplicates(KVs, [K|Ks], Dups);
- Ds -> alg_duplicates(KVs, [K|Ks], Dups++Ds)
+
+%%% Handle the algorithms list
+normalize_mod_alg_list(K, Vs, UseDefaultAlgs) ->
+ normalize_mod_alg_list(K,
+ ssh_transport:algo_two_spec_class(K),
+ Vs,
+ def_alg(K,UseDefaultAlgs)).
+
+
+normalize_mod_alg_list(_K, _, [], Default) ->
+ Default;
+
+normalize_mod_alg_list(K, true, [{client2server,L1}], [_,{server2client,L2}]) ->
+ [nml1(K,{client2server,L1}),
+ {server2client,L2}];
+
+normalize_mod_alg_list(K, true, [{server2client,L2}], [{client2server,L1},_]) ->
+ [{client2server,L1},
+ nml1(K,{server2client,L2})];
+
+normalize_mod_alg_list(K, true, [{server2client,L2},{client2server,L1}], _) ->
+ [nml1(K,{client2server,L1}),
+ nml1(K,{server2client,L2})];
+
+normalize_mod_alg_list(K, true, [{client2server,L1},{server2client,L2}], _) ->
+ [nml1(K,{client2server,L1}),
+ nml1(K,{server2client,L2})];
+
+normalize_mod_alg_list(K, true, L0, _) ->
+ L = nml(K,L0), % Throws errors
+ [{client2server,L},
+ {server2client,L}];
+
+normalize_mod_alg_list(K, false, L, _) ->
+ nml(K,L).
+
+
+nml1(K, {T,V}) when T==client2server ; T==server2client ->
+ {T, nml({K,T}, V)}.
+
+nml(K, L) ->
+ [error_in_check(K, "Bad value for this key") % This is a throw
+ || V <- L,
+ not is_atom(V)
+ ],
+ case L -- lists:usort(L) of
+ [] -> ok;
+ Dups -> error_in_check({K,Dups}, "Duplicates") % This is a throw
+ end,
+ L.
+
+
+def_alg(K, false) ->
+ case ssh_transport:algo_two_spec_class(K) of
+ false -> [];
+ true -> [{client2server,[]}, {server2client,[]}]
end;
-alg_duplicates([], _Ks, Dups) ->
- Dups.
-
-handle_pref_alg(Key,
- Vs=[{client2server,C2Ss=[_|_]},{server2client,S2Cs=[_|_]}],
- [{client2server,Sup_C2Ss},{server2client,Sup_S2Cs}]
- ) ->
- chk_alg_vs(Key, C2Ss, Sup_C2Ss),
- chk_alg_vs(Key, S2Cs, Sup_S2Cs),
- {Key, Vs};
-
-handle_pref_alg(Key,
- Vs=[{server2client,[_|_]},{client2server,[_|_]}],
- Sup=[{client2server,_},{server2client,_}]
- ) ->
- handle_pref_alg(Key, lists:reverse(Vs), Sup);
-
-handle_pref_alg(Key,
- Vs=[V|_],
- Sup=[{client2server,_},{server2client,_}]
- ) when is_atom(V) ->
- handle_pref_alg(Key, [{client2server,Vs},{server2client,Vs}], Sup);
-
-handle_pref_alg(Key,
- Vs=[V|_],
- Sup=[S|_]
- ) when is_atom(V), is_atom(S) ->
- chk_alg_vs(Key, Vs, Sup),
- {Key, Vs};
-
-handle_pref_alg(Key, Vs, _) ->
- error_in_check({Key,Vs}, "Badly formed list").
-
-chk_alg_vs(OptKey, Values, SupportedValues) ->
- case (Values -- SupportedValues) of
- [] -> Values;
- [none] -> [none]; % for testing only
- Bad -> error_in_check({OptKey,Bad}, "Unsupported value(s) found")
+def_alg(K, true) ->
+ ssh_transport:default_algorithms(K).
+
+
+
+check_preferred_algorithms(Algs) when is_list(Algs) ->
+ check_input_ok(Algs),
+ {true, normalize_mod_algs(Algs, true)};
+
+check_preferred_algorithms(_) ->
+ error_in_check(modify_algorithms, "Bad option value. List expected.").
+
+
+check_input_ok(Algs) ->
+ [error_in_check(KVs, "Bad preferred_algorithms")
+ || KVs <- Algs,
+ not is_tuple(KVs)
+ orelse (size(KVs) =/= 2)].
+
+%%%----------------------------------------------------------------
+final_preferred_algorithms(Options) ->
+ Result =
+ case ?GET_OPT(modify_algorithms, Options) of
+ undefined ->
+ rm_non_supported(true,
+ ?GET_OPT(preferred_algorithms, Options));
+ ModAlgs ->
+ rm_non_supported(false,
+ eval_ops(?GET_OPT(preferred_algorithms, Options),
+ ModAlgs))
+ end,
+ error_if_empty(Result), % Throws errors if any value list is empty
+ ?PUT_OPT({preferred_algorithms,Result}, Options).
+
+eval_ops(PrefAlgs, ModAlgs) ->
+ lists:foldl(fun eval_op/2, PrefAlgs, ModAlgs).
+
+eval_op({Op,AlgKVs}, PrefAlgs) ->
+ eval_op(Op, AlgKVs, PrefAlgs, []).
+
+eval_op(Op, [{C,L1}|T1], [{C,L2}|T2], Acc) ->
+ eval_op(Op, T1, T2, [{C,eval_op(Op,L1,L2,[])} | Acc]);
+
+eval_op(_, [], [], Acc) -> lists:reverse(Acc);
+eval_op(rm, Opt, Pref, []) when is_list(Opt), is_list(Pref) -> Pref -- Opt;
+eval_op(append, Opt, Pref, []) when is_list(Opt), is_list(Pref) -> (Pref--Opt) ++ Opt;
+eval_op(prepend, Opt, Pref, []) when is_list(Opt), is_list(Pref) -> Opt ++ (Pref--Opt).
+
+
+rm_non_supported(UnsupIsErrorFlg, KVs) ->
+ [{K,rmns(K,Vs, UnsupIsErrorFlg)} || {K,Vs} <- KVs].
+
+rmns(K, Vs, UnsupIsErrorFlg) ->
+ case ssh_transport:algo_two_spec_class(K) of
+ false ->
+ rm_unsup(Vs, ssh_transport:supported_algorithms(K), UnsupIsErrorFlg, K);
+ true ->
+ [{C, rm_unsup(Vsx, Sup, UnsupIsErrorFlg, {K,C})}
+ || {{C,Vsx},{C,Sup}} <- lists:zip(Vs,ssh_transport:supported_algorithms(K))
+ ]
end.
+rm_unsup(A, B, Flg, ErrInf) ->
+ case A--B of
+ Unsup=[_|_] when Flg==true -> error({eoptions,
+ {preferred_algorithms,{ErrInf,Unsup}},
+ "Unsupported value(s) found"
+ });
+ Unsup -> A -- Unsup
+ end.
+
+
+error_if_empty([{K,[]}|_]) ->
+ error({eoptions, K, "Empty resulting algorithm list"});
+error_if_empty([{K,[{client2server,[]}, {server2client,[]}]}]) ->
+ error({eoptions, K, "Empty resulting algorithm list"});
+error_if_empty([{K,[{client2server,[]}|_]} | _]) ->
+ error({eoptions, {K,client2server}, "Empty resulting algorithm list"});
+error_if_empty([{K,[_,{server2client,[]}|_]} | _]) ->
+ error({eoptions, {K,server2client}, "Empty resulting algorithm list"});
+error_if_empty([_|T]) ->
+ error_if_empty(T);
+error_if_empty([]) ->
+ ok.
+
%%%----------------------------------------------------------------
forbidden_option(K,V) ->
Txt = io_lib:format("The option '~s' is used internally. The "
diff --git a/lib/ssh/src/ssh_transport.erl b/lib/ssh/src/ssh_transport.erl
index 412f5de9de..c48c0800e4 100644
--- a/lib/ssh/src/ssh_transport.erl
+++ b/lib/ssh/src/ssh_transport.erl
@@ -34,6 +34,8 @@
-export([next_seqnum/1,
supported_algorithms/0, supported_algorithms/1,
default_algorithms/0, default_algorithms/1,
+ algo_classes/0, algo_class/1,
+ algo_two_spec_classes/0, algo_two_spec_class/1,
handle_packet_part/4,
handle_hello_version/1,
key_exchange_init_msg/1,
@@ -81,6 +83,23 @@ default_algorithms() -> [{K,default_algorithms(K)} || K <- algo_classes()].
algo_classes() -> [kex, public_key, cipher, mac, compression].
+algo_class(kex) -> true;
+algo_class(public_key) -> true;
+algo_class(cipher) -> true;
+algo_class(mac) -> true;
+algo_class(compression) -> true;
+algo_class(_) -> false.
+
+
+algo_two_spec_classes() -> [cipher, mac, compression].
+
+algo_two_spec_class(cipher) -> true;
+algo_two_spec_class(mac) -> true;
+algo_two_spec_class(compression) -> true;
+algo_two_spec_class(_) -> false.
+
+
+
default_algorithms(kex) ->
supported_algorithms(kex, [
'diffie-hellman-group1-sha1' % Gone in OpenSSH 7.3.p1
diff --git a/lib/ssh/test/ssh_protocol_SUITE.erl b/lib/ssh/test/ssh_protocol_SUITE.erl
index 0837fe7eaf..7da921adb2 100644
--- a/lib/ssh/test/ssh_protocol_SUITE.erl
+++ b/lib/ssh/test/ssh_protocol_SUITE.erl
@@ -34,8 +34,8 @@
-define(NEWLINE, <<"\r\n">>).
-define(REKEY_DATA_TMO, 65000).
-%%-define(DEFAULT_KEX, 'diffie-hellman-group1-sha1').
-define(DEFAULT_KEX, 'diffie-hellman-group14-sha256').
+-define(EXTRA_KEX, 'diffie-hellman-group1-sha1').
-define(CIPHERS, ['aes256-ctr','aes192-ctr','aes128-ctr','aes128-cbc','3des-cbc']).
-define(DEFAULT_CIPHERS, [{client2server,?CIPHERS}, {server2client,?CIPHERS}]).
@@ -60,7 +60,8 @@ all() ->
{group,authentication},
{group,packet_size_error},
{group,field_size_error},
- {group,ext_info}
+ {group,ext_info},
+ {group,preferred_algorithms}
].
groups() ->
@@ -96,7 +97,13 @@ groups() ->
no_ext_info_s2,
ext_info_s,
ext_info_c
- ]}
+ ]},
+ {preferred_algorithms, [], [preferred_algorithms,
+ modify_append,
+ modify_prepend,
+ modify_rm,
+ modify_combo
+ ]}
].
@@ -701,8 +708,6 @@ ext_info_s(Config) ->
%%%--------------------------------------------------------------------
%%% The client sends the extension
ext_info_c(Config) ->
- {User,_Pwd} = server_user_password(Config),
-
%% Create a listening socket as server socket:
{ok,InitialState} = ssh_trpt_test_lib:exec(listen),
HostPort = ssh_trpt_test_lib:server_host_port(InitialState),
@@ -757,10 +762,135 @@ ext_info_c(Config) ->
{result, Pid, Error} -> ct:fail("Error: ~p",[Error])
end.
+
+%%%----------------------------------------------------------------
+%%%
+preferred_algorithms(Config) ->
+ Ciphers = filter_supported(cipher, ?CIPHERS),
+ {error,{eoptions,{{preferred_algorithms,{kex,[some_unknown_algo]}},
+ "Unsupported value(s) found"}}} =
+ chk_pref_algs(Config,
+ [?DEFAULT_KEX],
+ Ciphers,
+ [{preferred_algorithms, [{kex,[some_unknown_algo,?DEFAULT_KEX]},
+ {cipher,Ciphers}
+ ]}
+ ]).
+
+%%%----------------------------------------------------------------
+%%%
+modify_append(Config) ->
+ Ciphers = filter_supported(cipher, ?CIPHERS),
+ {ok,_} =
+ chk_pref_algs(Config,
+ [?DEFAULT_KEX, ?EXTRA_KEX],
+ Ciphers,
+ [{preferred_algorithms, [{kex,[?DEFAULT_KEX]},
+ {cipher,Ciphers}
+ ]},
+ {modify_algorithms, [{append,[{kex,[some_unknown_algo,?EXTRA_KEX]}]}]}
+ ]).
+
+%%%----------------------------------------------------------------
+%%%
+modify_prepend(Config) ->
+ Ciphers = filter_supported(cipher, ?CIPHERS),
+ {ok,_} =
+ chk_pref_algs(Config,
+ [?EXTRA_KEX, ?DEFAULT_KEX],
+ Ciphers,
+ [{preferred_algorithms, [{kex,[?DEFAULT_KEX]},
+ {cipher,Ciphers}
+ ]},
+ {modify_algorithms, [{prepend,[{kex,[some_unknown_algo,?EXTRA_KEX]}]}]}
+ ]).
+
+%%%----------------------------------------------------------------
+%%%
+modify_rm(Config) ->
+ Ciphers = filter_supported(cipher, ?CIPHERS),
+ {ok,_} =
+ chk_pref_algs(Config,
+ [?DEFAULT_KEX],
+ tl(Ciphers),
+ [{preferred_algorithms, [{kex,[?DEFAULT_KEX,?EXTRA_KEX]},
+ {cipher,Ciphers}
+ ]},
+ {modify_algorithms, [{rm,[{kex,[some_unknown_algo,?EXTRA_KEX]},
+ {cipher,[hd(Ciphers)]}
+ ]}
+ ]}
+ ]).
+
+
+%%%----------------------------------------------------------------
+%%%
+modify_combo(Config) ->
+ Ciphers = filter_supported(cipher, ?CIPHERS),
+ LastC = lists:last(Ciphers),
+ {ok,_} =
+ chk_pref_algs(Config,
+ [?DEFAULT_KEX],
+ [LastC] ++ (tl(Ciphers)--[LastC]) ++ [hd(Ciphers)],
+ [{preferred_algorithms, [{kex,[?DEFAULT_KEX,?EXTRA_KEX]},
+ {cipher,Ciphers}
+ ]},
+ {modify_algorithms, [{rm,[{kex,[some_unknown_algo,?EXTRA_KEX]}
+ ]},
+ {prepend,[{cipher,[{server2client,[LastC]}]}
+ ]},
+ {append,[{cipher,[a,hd(Ciphers),b]}
+ ]}
+ ]}
+ ]).
+
%%%================================================================
%%%==== Internal functions ========================================
%%%================================================================
+chk_pref_algs(Config,
+ ExpectedKex,
+ ExpectedCiphers,
+ ServerPrefOpts) ->
+ %% Start the dameon
+ case ssh_test_lib:daemon(
+ [{send_ext_info,false},
+ {recv_ext_info,false},
+ {system_dir, system_dir(Config)}
+ | ServerPrefOpts])
+ of
+ {_,Host,Port} ->
+ %% Check the Kex part
+ ssh_trpt_test_lib:exec(
+ [{set_options, [print_ops, {print_messages,detail}]},
+ {connect, Host, Port,
+ [{silently_accept_hosts, true},
+ {user_dir, user_dir(Config)},
+ {user_interaction, false}
+ ]},
+ {send, hello},
+ receive_hello,
+ {match,
+ #ssh_msg_kexinit{
+ kex_algorithms = to_lists(ExpectedKex),
+ encryption_algorithms_server_to_client = to_lists(ExpectedCiphers),
+ _ = '_'},
+ receive_msg}
+ ]);
+ Error ->
+ Error
+ end.
+
+
+filter_supported(K, Algs) -> Algs -- (Algs--supported(K)).
+
+supported(K) -> proplists:get_value(
+ server2client,
+ ssh_transport:supported_algorithms(cipher)).
+
+to_lists(L) -> lists:map(fun erlang:atom_to_list/1, L).
+
+
%%%---- init_suite and end_suite ---------------------------------------
start_apps(Config) ->
catch ssh:stop(),