[0931098] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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| 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
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| 3 | "http://www.oasis-open.org/docbook/xml/4.3/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 "http://sunsite.ualberta.ca/pub/OpenBSD/OpenSSH/portable/openssh-&openssh-version;.tar.gz">
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| 8 | <!ENTITY openssh-download-ftp "ftp://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-&openssh-version;.tar.gz">
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[df7d6378] | 9 | <!ENTITY openssh-size "854 KB">
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| 10 | <!ENTITY openssh-buildsize "13.3 MB">
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| 11 | <!ENTITY openssh-time "0.40 SBU">
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[0931098] | 12 | ]>
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| 13 |
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[1708d1e9] | 14 | <sect1 id="openssh" xreflabel="OpenSSH-&openssh-version;">
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[a0f03b0] | 15 | <sect1info>
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[5cd0959d] | 16 | <othername>$LastChangedBy$</othername>
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| 17 | <date>$Date$</date>
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[a0f03b0] | 18 | </sect1info>
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[00bb024c] | 19 | <?dbhtml filename="openssh.html"?>
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[40330fcd] | 20 | <title>Open<acronym>SSH</acronym>-&openssh-version;</title>
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[f45b1953] | 21 |
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[0931098] | 22 | <sect2>
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[df7d6378] | 23 | <title>Introduction to
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| 24 | <application>Open<acronym>SSH</acronym></application></title>
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[0931098] | 25 |
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| 26 | <para>The <application>Open<acronym>SSH</acronym></application> package
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[df7d6378] | 27 | contains <command>ssh</command> clients and the <command>sshd</command> daemon.
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| 28 | This is useful for encrypting authentication and subsequent traffic over a
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| 29 | network.</para>
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[0931098] | 30 |
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| 31 | <sect3><title>Package information</title>
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| 32 | <itemizedlist spacing='compact'>
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| 33 | <listitem><para>Download (HTTP): <ulink url="&openssh-download-http;"/></para></listitem>
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| 34 | <listitem><para>Download (FTP): <ulink url="&openssh-download-ftp;"/></para></listitem>
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| 35 | <listitem><para>Download size: &openssh-size;</para></listitem>
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[518538f] | 36 | <listitem><para>Estimated disk space required: &openssh-buildsize;</para></listitem>
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[0931098] | 37 | <listitem><para>Estimated build time: &openssh-time;</para></listitem></itemizedlist>
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| 38 | </sect3>
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| 39 |
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[df7d6378] | 40 | <sect3><title><application>Open<acronym>SSH</acronym></application>
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| 41 | dependencies</title>
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[0931098] | 42 | <sect4><title>Required</title>
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[df7d6378] | 43 | <para><xref linkend="openssl"/></para>
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| 44 | </sect4>
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[0931098] | 45 | <sect4><title>Optional</title>
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[df7d6378] | 46 | <para><xref linkend="Linux_PAM"/>,
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| 47 | <xref linkend="tcpwrappers"/>,
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| 48 | X (<xref linkend="xfree86"/> or <xref linkend="xorg"/>),
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| 49 | <xref linkend="mitkrb"/> or <xref linkend="heimdal"/>,
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| 50 | <xref linkend="j2sdk"/>,
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| 51 | <xref linkend="net-tools"/> and
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[0931098] | 52 | <ulink url="http://www.opensc.org/">OpenSC</ulink>
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| 53 | </para></sect4>
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| 54 | </sect3>
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| 55 |
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| 56 | </sect2>
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| 57 |
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| 58 | <sect2>
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[df7d6378] | 59 | <title>Installation of
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| 60 | <application>Open<acronym>SSH</acronym></application></title>
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[0931098] | 61 |
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| 62 | <para><application>Open<acronym>SSH</acronym></application> runs as two
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[df7d6378] | 63 | processes when connecting to other computers. The first process is a
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| 64 | privileged process and controls the issuance of privileges as necessary.
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| 65 | The second process communicates with the network. Additional installation
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| 66 | steps are necessary to set up the proper environment, which are performed
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| 67 | by the following commands:</para>
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[0931098] | 68 |
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| 69 | <screen><userinput><command>mkdir /var/empty &&
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| 70 | chown root:sys /var/empty &&
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| 71 | groupadd sshd &&
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| 72 | useradd -c 'sshd privsep' -d /var/empty -g sshd -s /bin/false sshd</command></userinput></screen>
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| 73 |
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| 74 | <para><application>OpenSSH</application> is very sensitive to changes in the
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| 75 | linked <application>OpenSSL</application> libraries. If you recompile
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| 76 | <application>OpenSSL</application>, <application>OpenSSH</application> may
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[df7d6378] | 77 | fail to startup. An alternative is to link against the static
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| 78 | <application>OpenSSL</application> library. To link against the static
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| 79 | library, execute the following command:</para>
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[0931098] | 80 |
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| 81 | <screen><userinput><command>sed -i "s:-lcrypto:/usr/lib/libcrypto.a:g" configure</command></userinput></screen>
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| 82 |
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| 83 | <para>Install <application>Open<acronym>SSH</acronym></application> by running
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| 84 | the following commands:</para>
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| 85 |
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| 86 | <screen><userinput><command>./configure --prefix=/usr --sysconfdir=/etc/ssh \
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| 87 | --libexecdir=/usr/sbin --with-md5-passwords &&
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| 88 | make &&
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| 89 | make install</command></userinput></screen>
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| 90 |
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| 91 | </sect2>
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| 92 |
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| 93 | <sect2>
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| 94 | <title>Command explanations</title>
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| 95 |
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| 96 | <para><parameter>--sysconfdir=/etc/ssh</parameter>: This prevents the
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[df7d6378] | 97 | configuration files from going to
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| 98 | <filename class="directory">/usr/etc</filename>.</para>
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[0931098] | 99 |
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| 100 | <para><parameter>--with-md5-passwords</parameter>: This is required
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| 101 | if you made the changes recommended by the shadowpasswd_plus
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| 102 | <acronym>LFS</acronym> hint on
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| 103 | your <acronym>SSH</acronym> server when you installed the Shadow Password
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| 104 | Suite or if you access a <acronym>SSH</acronym> server that authenticates by
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| 105 | user passwords encrypted with md5. </para>
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| 106 |
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| 107 | <para><parameter>--libexecdir=/usr/sbin</parameter>:
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[df7d6378] | 108 | <application>Open<acronym>SSH</acronym></application> installs programs called
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| 109 | by programs in <filename class="directory">/usr/libexec</filename>.
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[0931098] | 110 | <command>sftp-server</command> is a <command>sshd</command>
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| 111 | utility and <command>ssh-askpass</command> is a <command>ssh-add</command>
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[df7d6378] | 112 | utility that is installed as a link to <command>X11-ssh-askpass</command>.
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[0931098] | 113 | Both of these should go in <filename class="directory">/usr/sbin</filename>
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| 114 | not <filename class="directory">/usr/libexec</filename>.</para>
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| 115 |
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| 116 | </sect2>
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| 117 |
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| 118 | <sect2>
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| 119 | <title>Configuring <application>Open<acronym>SSH</acronym></application></title>
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| 120 |
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| 121 | <sect3><title>Config files</title>
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| 122 |
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[df7d6378] | 123 | <para><filename>/etc/ssh/ssh_config</filename> and
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[0931098] | 124 | <filename>/etc/ssh/sshd_config </filename></para>
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[df7d6378] | 125 |
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| 126 | <para>There are no required changes to either of these files. However,
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[0931098] | 127 | you may wish to view them to make changes for appropriate security to
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[90631d03] | 128 | your system. One recomended change is that you disable root login via
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| 129 | ssh. Execute the following command to disable root login via ssh:</para>
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| 130 |
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| 131 | <screen><userinput><command>echo "PermitRootLogin no" >> /etc/ssh/sshd_config</command></userinput></screen>
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| 132 |
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| 133 | <para>Additional configuration information can be found in the man pages for
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[df7d6378] | 134 | <command>sshd</command>, <command>ssh</command> and
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| 135 | <command>ssh-agent</command></para>
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[90631d03] | 136 |
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[0931098] | 137 | </sect3>
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| 138 |
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| 139 | <sect3><title>sshd init.d script</title>
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| 140 |
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[df7d6378] | 141 | <para>To start the <acronym>SSH</acronym> server at system boot, install the
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| 142 | <filename>/etc/rc.d/init.d/sshd</filename> init script included in the
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| 143 | <xref linkend="intro-important-bootscripts"/> package.</para>
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| 144 |
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[0931098] | 145 | <screen><userinput><command>make install-sshd</command></userinput></screen>
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| 146 |
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| 147 | </sect3>
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| 148 |
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| 149 | </sect2>
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| 150 |
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| 151 | <sect2>
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| 152 | <title>Contents</title>
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| 153 |
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[df7d6378] | 154 | <para>The <application>Open<acronym>SSH</acronym></application> package
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| 155 | contains <command>ssh</command>, <command>sshd</command>,
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| 156 | <command>ssh-agent</command>, <command>ssh-add</command>,
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| 157 | <command>sftp</command>, <command>scp</command>,
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| 158 | <command>ssh-keygen</command>, <command>sftp-server</command> and
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[0931098] | 159 | <command>ssh-keyscan</command>.</para>
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| 160 |
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| 161 | </sect2>
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| 162 |
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| 163 | <sect2><title>Description</title>
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| 164 |
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| 165 | <sect3><title>ssh</title>
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[df7d6378] | 166 | <para>The basic <command>rlogin</command>/<command>rsh</command>-like
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| 167 | client program.</para></sect3>
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[0931098] | 168 |
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| 169 | <sect3><title>sshd</title>
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[df7d6378] | 170 | <para>The daemon that listens for <command>ssh</command> login
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| 171 | requests.</para></sect3>
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[0931098] | 172 |
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| 173 | <sect3><title>ssh-agent</title>
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| 174 | <para>An authentication agent that can store private keys.</para></sect3>
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| 175 |
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| 176 | <sect3><title>ssh-add</title>
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| 177 | <para>Tool which adds keys to the <command>ssh-agent</command>.</para></sect3>
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| 178 |
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| 179 | <sect3><title>sftp</title>
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| 180 | <para><acronym>FTP</acronym>-like program that works over
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| 181 | <acronym>SSH</acronym>1 and <acronym>SSH</acronym>2 protocols.</para></sect3>
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| 182 |
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| 183 | <sect3><title>scp</title>
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[df7d6378] | 184 | <para>File copy program that acts like <command>rcp</command>.</para></sect3>
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[0931098] | 185 |
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| 186 | <sect3><title>ssh-keygen</title>
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| 187 | <para>Key generation tool.</para></sect3>
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| 188 |
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| 189 | <sect3><title>sftp-server</title>
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| 190 | <para><acronym>SFTP</acronym> server subsystem.</para></sect3>
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| 191 |
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| 192 | <sect3><title>ssh-keyscan</title>
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[df7d6378] | 193 | <para>Utility for gathering public host keys from a number of
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| 194 | hosts.</para></sect3>
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[0931098] | 195 |
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| 196 | </sect2>
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[f45b1953] | 197 |
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| 198 | </sect1>
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| 199 |
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