1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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4 | <!ENTITY % general-entities SYSTEM "../../general.ent">
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5 | %general-entities;
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6 |
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7 | <!ENTITY openssh-download-http
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8 | "http://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-&openssh-version;.tar.gz">
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9 | <!ENTITY openssh-download-ftp
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10 | "ftp://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-&openssh-version;.tar.gz">
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11 | <!ENTITY openssh-md5sum "13009a9156510d8f27e752659075cced">
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12 | <!ENTITY openssh-size "1.5 MB">
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13 | <!ENTITY openssh-buildsize "43 MB (51 MB, with tests)">
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14 | <!ENTITY openssh-time "0.4 SBU (running the tests takes 10+ minutes,
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15 | irrespective of processor speed)">
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16 | <!-- fo is not running the tests-->
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17 | ]>
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18 |
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19 | <sect1 id="openssh" xreflabel="OpenSSH-&openssh-version;">
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20 | <?dbhtml filename="openssh.html"?>
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21 |
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22 | <sect1info>
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23 | <othername>$LastChangedBy$</othername>
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24 | <date>$Date$</date>
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25 | </sect1info>
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26 |
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27 | <title>OpenSSH-&openssh-version;</title>
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28 |
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29 | <indexterm zone="openssh">
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30 | <primary sortas="a-OpenSSH">OpenSSH</primary>
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31 | </indexterm>
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32 |
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33 | <sect2 role="package">
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34 | <title>Introduction to OpenSSH</title>
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35 |
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36 | <para>
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37 | The <application>OpenSSH</application> package contains
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38 | <command>ssh</command> clients and the <command>sshd</command> daemon. This
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39 | is useful for encrypting authentication and subsequent traffic over a
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40 | network. The <command>ssh</command> and <command>scp</command> commands are
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41 | secure implementions of <command>telnet</command> and <command>rcp</command>
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42 | respectively.
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43 | </para>
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44 |
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45 | &lfs79_checked;&gcc6_checked;
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46 |
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47 | <bridgehead renderas="sect3">Package Information</bridgehead>
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48 | <itemizedlist spacing="compact">
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49 | <listitem>
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50 | <para>
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51 | Download (HTTP): <ulink url="&openssh-download-http;"/>
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52 | </para>
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53 | </listitem>
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54 | <listitem>
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55 | <para>
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56 | Download (FTP): <ulink url="&openssh-download-ftp;"/>
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57 | </para>
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58 | </listitem>
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59 | <listitem>
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60 | <para>
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61 | Download MD5 sum: &openssh-md5sum;
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62 | </para>
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63 | </listitem>
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64 | <listitem>
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65 | <para>
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66 | Download size: &openssh-size;
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67 | </para>
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68 | </listitem>
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69 | <listitem>
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70 | <para>
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71 | Estimated disk space required: &openssh-buildsize;
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72 | </para>
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73 | </listitem>
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74 | <listitem>
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75 | <para>
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76 | Estimated build time: &openssh-time;
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77 | </para>
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78 | </listitem>
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79 | </itemizedlist>
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80 |
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81 | <bridgehead renderas="sect3">OpenSSH Dependencies</bridgehead>
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82 |
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83 | <bridgehead renderas="sect4">Required</bridgehead>
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84 | <para role="required">
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85 | <xref linkend="openssl"/> or
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86 | <ulink url="http://www.libressl.org/">LibreSSL Portable</ulink></para>
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87 |
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88 | <bridgehead renderas="sect4">Optional</bridgehead>
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89 | <para role="optional">
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90 | <xref linkend="linux-pam"/>,
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91 | <xref linkend="x-window-system"/>,
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92 | <xref linkend="mitkrb"/>,
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93 | <ulink url="http://www.thrysoee.dk/editline/">libedit</ulink>,
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94 | <ulink url="https://github.com/OpenSC/OpenSC/wiki">OpenSC</ulink>, and
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95 | <ulink url="http://www.citi.umich.edu/projects/smartcard/sectok.html">libsectok</ulink>
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96 | </para>
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97 |
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98 | <bridgehead renderas="sect4">Optional Runtime (Used only to gather entropy)</bridgehead>
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99 | <para role="optional">
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100 | <xref linkend="openjdk"/>,
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101 | <xref linkend="net-tools"/>, and
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102 | <xref linkend="sysstat"/>
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103 | </para>
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104 |
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105 | <para condition="html" role="usernotes">
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106 | User Notes: <ulink url="&blfs-wiki;/OpenSSH"/>
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107 | </para>
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108 | </sect2>
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109 |
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110 | <sect2 role="installation">
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111 | <title>Installation of OpenSSH</title>
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112 |
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113 | <para>
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114 | <application>OpenSSH</application> runs as two processes when connecting
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115 | to other computers. The first process is a privileged process and controls
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116 | the issuance of privileges as necessary. The second process communicates
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117 | with the network. Additional installation steps are necessary to set up
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118 | the proper environment, which are performed by issuing the following
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119 | commands as the <systemitem class="username">root</systemitem> user:
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120 | </para>
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121 |
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122 | <screen role="root"><userinput>install -v -m700 -d /var/lib/sshd &&
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123 | chown -v root:sys /var/lib/sshd &&
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124 |
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125 | groupadd -g 50 sshd &&
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126 | useradd -c 'sshd PrivSep' \
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127 | -d /var/lib/sshd \
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128 | -g sshd \
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129 | -s /bin/false \
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130 | -u 50 sshd</userinput></screen>
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131 |
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132 | <para>
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133 | Install <application>OpenSSH</application> by running the following
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134 | commands:
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135 | </para>
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136 |
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137 | <screen><userinput>./configure --prefix=/usr \
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138 | --sysconfdir=/etc/ssh \
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139 | --with-md5-passwords \
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140 | --with-privsep-path=/var/lib/sshd &&
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141 | make</userinput></screen>
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142 |
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143 | <para>
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144 | The testsuite requires an installed copy of <command>scp</command> to
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145 | complete the multiplexing tests. To run the test suite, first copy the
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146 | <command>scp</command> program to
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147 | <filename class="directory">/usr/bin</filename>, making sure that you
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148 | back up any existing copy first.
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149 | </para>
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150 |
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151 | <para>
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152 | To test the results, issue: <command>make tests</command>.
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153 | </para>
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154 |
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155 | <!-- commenting this, I get "all tests passed" [ ken ]
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156 | NB tests should be run as _user_ but the role in the comment is root
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157 |
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158 | commenting [ bruce ]: There are a couple of tests that want root.
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159 | The log mentions that SUDO is not set. These skipped tests are
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160 | ignored and the end says 'all tests passed' even when not root
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161 |
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162 | <para>
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163 | To run the test suite, issue the following commands:
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164 | </para>
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165 |
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166 | <screen role="root"><userinput>make tests 2>&1 | tee check.log
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167 | grep FATAL check.log</userinput></screen>
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168 |
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169 | <para>
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170 | If the above command produces no 'FATAL' errors, then proceed with the
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171 | installation, as the <systemitem class="username">root</systemitem> user:
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172 | </para>-->
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173 | <para>
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174 | Now, as the <systemitem class="username">root</systemitem> user:
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175 | </para>
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176 |
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177 | <screen role="root"><userinput>make install &&
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178 | install -v -m755 contrib/ssh-copy-id /usr/bin &&
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179 |
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180 | install -v -m644 contrib/ssh-copy-id.1 \
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181 | /usr/share/man/man1 &&
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182 | install -v -m755 -d /usr/share/doc/openssh-&openssh-version; &&
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183 | install -v -m644 INSTALL LICENCE OVERVIEW README* \
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184 | /usr/share/doc/openssh-&openssh-version;</userinput></screen>
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185 | </sect2>
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186 |
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187 | <sect2 role="commands">
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188 | <title>Command Explanations</title>
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189 |
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190 | <para>
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191 | <parameter>--sysconfdir=/etc/ssh</parameter>: This prevents the
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192 | configuration files from being installed in
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193 | <filename class="directory">/usr/etc</filename>.
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194 | </para>
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195 |
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196 | <para>
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197 | <parameter>--with-md5-passwords</parameter>: This enables the use of MD5
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198 | passwords.
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199 | </para>
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200 |
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201 | <para>
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202 | <parameter>--with-pam</parameter>: This parameter enables
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203 | <application>Linux-PAM</application> support in the build.
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204 | </para>
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205 |
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206 | <para>
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207 | <parameter>--with-xauth=/usr/bin/xauth</parameter>: Set the default
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208 | location for the <command>xauth</command> binary for X authentication.
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209 | Change the location if <command>xauth</command> will be installed to a
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210 | different path. This can also be controlled from
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211 | <filename>sshd_config</filename> with the XAuthLocation keyword. You can
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212 | omit this switch if <application>Xorg</application> is already installed.
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213 | </para>
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214 |
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215 | <para>
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216 | <parameter>--with-kerberos5=/usr</parameter>: This option is used to
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217 | include Kerberos 5 support in the build.
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218 | </para>
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219 |
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220 | <para>
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221 | <parameter>--with-libedit</parameter>: This option enables line editing
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222 | and history features for <command>sftp</command>.
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223 | </para>
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224 |
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225 | </sect2>
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226 |
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227 | <sect2 role="configuration">
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228 | <title>Configuring OpenSSH</title>
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229 |
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230 | <sect3 id="openssh-config">
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231 | <title>Config Files</title>
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232 |
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233 | <para>
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234 | <filename>~/.ssh/*</filename>,
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235 | <filename>/etc/ssh/ssh_config</filename>, and
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236 | <filename>/etc/ssh/sshd_config</filename>
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237 | </para>
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238 |
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239 | <indexterm zone="openssh openssh-config">
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240 | <primary sortas="e-AA.ssh">~/.ssh/*</primary>
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241 | </indexterm>
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242 |
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243 | <indexterm zone="openssh openssh-config">
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244 | <primary sortas="e-etc-ssh-ssh_config">/etc/ssh/ssh_config</primary>
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245 | </indexterm>
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246 |
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247 | <indexterm zone="openssh openssh-config">
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248 | <primary sortas="e-etc-ssh-sshd_config">/etc/ssh/sshd_config</primary>
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249 | </indexterm>
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250 |
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251 | <para>
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252 | There are no required changes to any of these files. However,
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253 | you may wish to view the
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254 | <filename class='directory'>/etc/ssh/</filename> files and make any
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255 | changes appropriate for the security of your system. One recommended
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256 | change is that you disable
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257 | <systemitem class='username'>root</systemitem> login via
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258 | <command>ssh</command>. Execute the following command as the
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259 | <systemitem class='username'>root</systemitem> user to disable
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260 | <systemitem class='username'>root</systemitem> login via
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261 | <command>ssh</command>:
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262 | </para>
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263 |
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264 | <screen role="root"><userinput>echo "PermitRootLogin no" >> /etc/ssh/sshd_config</userinput></screen>
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265 |
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266 | <para>
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267 | If you want to be able to log in without typing in your password, first
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268 | create ~/.ssh/id_rsa and ~/.ssh/id_rsa.pub with
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269 | <command>ssh-keygen</command> and then copy ~/.ssh/id_rsa.pub to
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270 | ~/.ssh/authorized_keys on the remote computer that you want to log into.
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271 | You'll need to change REMOTE_USERNAME and REMOTE_HOSTNAME for the username and hostname of the remote
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272 | computer and you'll also need to enter your password for the ssh-copy-id command
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273 | to succeed:
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274 | </para>
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275 |
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276 | <screen><userinput>ssh-keygen &&
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277 | ssh-copy-id -i ~/.ssh/id_rsa.pub <replaceable>REMOTE_USERNAME</replaceable>@<replaceable>REMOTE_HOSTNAME</replaceable></userinput></screen>
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278 |
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279 | <para>
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280 | Once you've got passwordless logins working it's actually more secure
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281 | than logging in with a password (as the private key is much longer than
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282 | most people's passwords). If you would like to now disable password
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283 | logins, as the <systemitem class="username">root</systemitem> user:
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284 | </para>
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285 |
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286 |
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287 | <screen role="root"><userinput>echo "PasswordAuthentication no" >> /etc/ssh/sshd_config &&
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288 | echo "ChallengeResponseAuthentication no" >> /etc/ssh/sshd_config</userinput></screen>
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289 |
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290 | <para>
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291 | If you added <application>LinuxPAM</application> support and you want
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292 | ssh to use it then you will need to add a configuration file for
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293 | <application>sshd</application> and enable use of
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294 | <application>LinuxPAM</application>. Note, ssh only uses PAM to check
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295 | passwords, if you've disabled password logins these commands are not
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296 | needed. If you want to use PAM issue the following commands as the
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297 | <systemitem class='username'>root</systemitem> user:
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298 | </para>
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299 |
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300 | <screen role="root"><userinput>sed 's@d/login@d/sshd@g' /etc/pam.d/login > /etc/pam.d/sshd &&
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301 | chmod 644 /etc/pam.d/sshd &&
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302 | echo "UsePAM yes" >> /etc/ssh/sshd_config</userinput></screen>
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303 |
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304 | <para>
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305 | Additional configuration information can be found in the man
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306 | pages for <command>sshd</command>, <command>ssh</command> and
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307 | <command>ssh-agent</command>.
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308 | </para>
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309 | </sect3>
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310 |
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311 | <sect3 id="openssh-init">
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312 | <title>Boot Script</title>
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313 |
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314 | <para>
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315 | To start the SSH server at system boot, install the
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316 | <filename>/etc/rc.d/init.d/sshd</filename> init script included
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317 | in the <xref linkend="bootscripts" revision="sysv"/>
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318 | <xref linkend="systemd-units" revision="systemd"/> package.
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319 | </para>
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320 |
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321 | <indexterm zone="openssh openssh-init">
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322 | <primary sortas="f-sshd">sshd</primary>
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323 | </indexterm>
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324 |
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325 | <screen role="root"><userinput>make install-sshd</userinput></screen>
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326 | </sect3>
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327 | </sect2>
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328 |
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329 | <sect2 role="content">
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330 | <title>Contents</title>
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331 |
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332 | <segmentedlist>
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333 | <segtitle>Installed Programs</segtitle>
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334 | <segtitle>Installed Libraries</segtitle>
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335 | <segtitle>Installed Directories</segtitle>
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336 |
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337 | <seglistitem>
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338 | <seg>
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339 | scp, sftp, slogin (symlink to ssh), ssh, ssh-add, ssh-agent,
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340 | ssh-copy-id, ssh-keygen, ssh-keyscan, and sshd
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341 | </seg>
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342 | <seg>
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343 | None
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344 | </seg>
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345 | <seg>
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346 | /etc/ssh,
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347 | /usr/share/doc/openssh-&openssh-version;, and
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348 | /var/lib/sshd
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349 | </seg>
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350 | </seglistitem>
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351 | </segmentedlist>
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352 |
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353 | <variablelist>
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354 | <bridgehead renderas="sect3">Short Descriptions</bridgehead>
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355 | <?dbfo list-presentation="list"?>
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356 | <?dbhtml list-presentation="table"?>
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357 |
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358 | <varlistentry id="scp">
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359 | <term><command>scp</command></term>
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360 | <listitem>
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361 | <para>
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362 | is a file copy program that acts like <command>rcp</command> except
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363 | it uses an encrypted protocol.
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364 | </para>
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365 | <indexterm zone="openssh scp">
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366 | <primary sortas="b-scp">scp</primary>
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367 | </indexterm>
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368 | </listitem>
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369 | </varlistentry>
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370 |
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371 | <varlistentry id="sftp">
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372 | <term><command>sftp</command></term>
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373 | <listitem>
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374 | <para>
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375 | is an FTP-like program that works over the SSH1 and SSH2 protocols.
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376 | </para>
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377 | <indexterm zone="openssh sftp">
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378 | <primary sortas="b-sftp">sftp</primary>
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379 | </indexterm>
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380 | </listitem>
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381 | </varlistentry>
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382 |
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383 | <varlistentry id="slogin">
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384 | <term><command>slogin</command></term>
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385 | <listitem>
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386 | <para>
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387 | is a symlink to <command>ssh</command>.
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388 | </para>
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389 | <indexterm zone="openssh slogin">
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390 | <primary sortas="b-slogin">slogin</primary>
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391 | </indexterm>
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392 | </listitem>
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393 | </varlistentry>
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394 |
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395 | <varlistentry id="ssh">
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396 | <term><command>ssh</command></term>
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397 | <listitem>
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398 | <para>
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399 | is an <command>rlogin</command>/<command>rsh</command>-like client
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400 | program except it uses an encrypted protocol.
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401 | </para>
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402 | <indexterm zone="openssh ssh">
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403 | <primary sortas="b-ssh">ssh</primary>
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404 | </indexterm>
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405 | </listitem>
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406 | </varlistentry>
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407 |
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408 | <varlistentry id="sshd">
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409 | <term><command>sshd</command></term>
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410 | <listitem>
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411 | <para>
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412 | is a daemon that listens for <command>ssh</command> login requests.
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413 | </para>
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414 | <indexterm zone="openssh sshd">
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415 | <primary sortas="b-sshd">sshd</primary>
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416 | </indexterm>
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417 | </listitem>
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418 | </varlistentry>
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419 |
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420 | <varlistentry id="ssh-add">
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421 | <term><command>ssh-add</command></term>
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422 | <listitem>
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423 | <para>
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424 | is a tool which adds keys to the <command>ssh-agent</command>.
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425 | </para>
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426 | <indexterm zone="openssh ssh-add">
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427 | <primary sortas="b-ssh-add">ssh-add</primary>
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428 | </indexterm>
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429 | </listitem>
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430 | </varlistentry>
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431 |
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432 | <varlistentry id="ssh-agent">
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433 | <term><command>ssh-agent</command></term>
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434 | <listitem>
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435 | <para>
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436 | is an authentication agent that can store private keys.
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437 | </para>
|
---|
438 | <indexterm zone="openssh ssh-agent">
|
---|
439 | <primary sortas="b-ssh-agent">ssh-agent</primary>
|
---|
440 | </indexterm>
|
---|
441 | </listitem>
|
---|
442 | </varlistentry>
|
---|
443 |
|
---|
444 | <varlistentry id="ssh-copy-id">
|
---|
445 | <term><command>ssh-copy-id</command></term>
|
---|
446 | <listitem>
|
---|
447 | <para>
|
---|
448 | is a script that enables logins on remote machine using local keys.
|
---|
449 | </para>
|
---|
450 | <indexterm zone="openssh ssh-copy-id">
|
---|
451 | <primary sortas="b-ssh-copy-id">ssh-copy-id</primary>
|
---|
452 | </indexterm>
|
---|
453 | </listitem>
|
---|
454 | </varlistentry>
|
---|
455 |
|
---|
456 | <varlistentry id="ssh-keygen">
|
---|
457 | <term><command>ssh-keygen</command></term>
|
---|
458 | <listitem>
|
---|
459 | <para>
|
---|
460 | is a key generation tool.
|
---|
461 | </para>
|
---|
462 | <indexterm zone="openssh ssh-keygen">
|
---|
463 | <primary sortas="b-ssh-keygen">ssh-keygen</primary>
|
---|
464 | </indexterm>
|
---|
465 | </listitem>
|
---|
466 | </varlistentry>
|
---|
467 |
|
---|
468 | <varlistentry id="ssh-keyscan">
|
---|
469 | <term><command>ssh-keyscan</command></term>
|
---|
470 | <listitem>
|
---|
471 | <para>
|
---|
472 | is a utility for gathering public host keys from a number of hosts.
|
---|
473 | </para>
|
---|
474 | <indexterm zone="openssh ssh-keyscan">
|
---|
475 | <primary sortas="b-ssh-keyscan">ssh-keyscan</primary>
|
---|
476 | </indexterm>
|
---|
477 | </listitem>
|
---|
478 | </varlistentry>
|
---|
479 |
|
---|
480 | </variablelist>
|
---|
481 | </sect2>
|
---|
482 | </sect1>
|
---|