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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!ENTITY TIMESTAMP "2011-08-08">
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<!ENTITY TIMESTAMP "2018-02-08">
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<!ENTITY % common SYSTEM "common.ent">
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<firstname>Björn</firstname>
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<surname>Påhlsson</surname>
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<email>belorn@fukt.bsnet.se</email>
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<email>belorn@recompile.se</email>
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<firstname>Teddy</firstname>
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<surname>Hogeborn</surname>
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<email>teddy@fukt.bsnet.se</email>
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<email>teddy@recompile.se</email>
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<holder>Teddy Hogeborn</holder>
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<holder>Björn Påhlsson</holder>
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<refsect1 id="introduction">
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<title>INTRODUCTION</title>
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<!-- This paragraph is a combination and paraphrase of two
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quotes from the 1995 movie “The Usual Suspects”. -->
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You know how it is. You’ve heard of it happening. The Man
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comes and takes away your servers, your friends’ servers, the
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servers of everybody in the same hosting facility. The servers
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<refsect2 id="sniff">
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<title>How about sniffing the network traffic and decrypting it
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later by physically grabbing the Mandos client and using its
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We only use <acronym>PFS</acronym> (Perfect Forward Security)
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key exchange algorithms in TLS, which protects against this.
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<refsect2 id="physgrab">
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<title>Physically grabbing the Mandos server computer?</title>
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<refsect2 id="fakeping">
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<title>Faking ping replies?</title>
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<refsect2 id="fakecheck">
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<title>Faking checker results?</title>
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The default for the server is to use
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If the Mandos client does not have an SSH server, the default
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is for the Mandos server to use
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<quote><literal>fping</literal></quote>, the replies to which
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could be faked to eliminate the timeout. But this could
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easily be changed to any shell command, with any security
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measures you like. It could, for instance, be changed to an
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SSH command with strict keychecking, which could not be faked.
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Or IPsec could be used for the ping packets, making them
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measures you like. If the Mandos client
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<emphasis>has</emphasis> an SSH server, the default
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configuration (as generated by
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<command>mandos-keygen</command> with the
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<option>--password</option> option) is for the Mandos server
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to use an <command>ssh-keyscan</command> command with strict
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keychecking, which can not be faked. Alternatively, IPsec
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could be used for the ping packets, making them secure.