mirror of
https://github.com/Zeckmathederg/glfs.git
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9f12e36459
git-svn-id: svn://svn.linuxfromscratch.org/BLFS/trunk/BOOK@6192 af4574ff-66df-0310-9fd7-8a98e5e911e0
375 lines
14 KiB
XML
375 lines
14 KiB
XML
<?xml version="1.0" encoding="ISO-8859-1"?>
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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
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<!ENTITY % general-entities SYSTEM "../../general.ent">
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%general-entities;
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<!ENTITY openssh-download-http "http://sunsite.ualberta.ca/pub/OpenBSD/OpenSSH/portable/openssh-&openssh-version;.tar.gz">
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<!ENTITY openssh-download-ftp "ftp://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-&openssh-version;.tar.gz">
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<!ENTITY openssh-md5sum "7e9880ac20a9b9db0d3fea30a9ff3d46">
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<!ENTITY openssh-size "920 KB">
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<!ENTITY openssh-buildsize "15.3 MB">
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<!ENTITY openssh-time "0.5 SBU (additional 0.7 SBU to run the test suite)">
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]>
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<sect1 id="openssh" xreflabel="OpenSSH-&openssh-version;">
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<?dbhtml filename="openssh.html"?>
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<sect1info>
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<othername>$LastChangedBy$</othername>
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<date>$Date$</date>
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</sect1info>
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<title>OpenSSH-&openssh-version;</title>
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<indexterm zone="openssh">
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<primary sortas="a-OpenSSH">OpenSSH</primary>
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</indexterm>
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<sect2 role="package">
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<title>Introduction to OpenSSH</title>
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<para>The <application>OpenSSH</application> package contains
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<command>ssh</command> clients and the <command>sshd</command> daemon.
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This is useful for encrypting authentication and subsequent traffic
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over a network.</para>
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<bridgehead renderas="sect3">Package Information</bridgehead>
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<itemizedlist spacing="compact">
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<listitem>
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<para>Download (HTTP): <ulink url="&openssh-download-http;"/></para>
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</listitem>
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<listitem>
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<para>Download (FTP): <ulink url="&openssh-download-ftp;"/></para>
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</listitem>
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<listitem>
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<para>Download MD5 sum: &openssh-md5sum;</para>
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</listitem>
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<listitem>
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<para>Download size: &openssh-size;</para>
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</listitem>
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<listitem>
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<para>Estimated disk space required: &openssh-buildsize;</para>
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</listitem>
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<listitem>
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<para>Estimated build time: &openssh-time;</para>
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</listitem>
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</itemizedlist>
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<bridgehead renderas="sect3">OpenSSH Dependencies</bridgehead>
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<bridgehead renderas="sect4">Required</bridgehead>
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<para role="required"><xref linkend="openssl"/></para>
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<bridgehead renderas="sect4">Optional</bridgehead>
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<para role="optional"><xref linkend="linux-pam"/>,
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<xref linkend="tcpwrappers"/>,
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<xref linkend="x-window-system"/>,
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<xref linkend="mitkrb"/> or <xref linkend="heimdal"/>,
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<xref linkend="jdk"/>,
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<xref linkend="net-tools"/>,
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<xref linkend="sysstat"/>,
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<ulink url="http://www.opensc-project.org/">OpenSC</ulink>, and
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<ulink
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url="http://www.citi.umich.edu/projects/smartcard/sectok.html">libsectok</ulink></para>
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<para condition="html" role="usernotes">User Notes:
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<ulink url='&blfs-wiki;/OpenSSH'/></para>
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</sect2>
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<sect2 role="installation">
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<title>Installation of OpenSSH</title>
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<para><application>OpenSSH</application> runs as two processes when
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connecting to other computers. The first process is a privileged process
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and controls the issuance of privileges as necessary. The second process
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communicates with the network. Additional installation steps are necessary
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to set up the proper environment, which are performed by the following
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commands:</para>
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<screen role="root"><userinput>install -v -m700 -d /var/lib/sshd &&
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chown -v root:sys /var/lib/sshd &&
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groupadd -g 50 sshd &&
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useradd -c 'sshd PrivSep' -d /var/lib/sshd -g sshd \
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-s /bin/false -u 50 sshd</userinput></screen>
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<para><application>OpenSSH</application> is very sensitive to changes in
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the linked <application>OpenSSL</application> libraries. If you recompile
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<application>OpenSSL</application>, <application>OpenSSH</application> may
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fail to startup. An alternative is to link against the static
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<application>OpenSSL</application> library. To link against the static
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library, execute the following command:</para>
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<screen><userinput>sed -i "s:-lcrypto:/usr/lib/libcrypto.a -ldl:g" configure</userinput></screen>
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<para>Install <application>OpenSSH</application> by running
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the following commands:</para>
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<screen><userinput>sed -i "s/lkrb5 -ldes/lkrb5/" configure &&
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./configure --prefix=/usr --sysconfdir=/etc/ssh \
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--libexecdir=/usr/lib/openssh --with-md5-passwords \
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--with-privsep-path=/var/lib/sshd &&
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make</userinput></screen>
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<!-- Leaving this bunch of stuff for now. The description of all
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this is now in the Command Explanatations, however.
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<para>If you use <application>Heimdal</application> as your Kerberos5
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implementation and you linked the <application>Heimdal</application>
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libraries into the <application>OpenSSH</application> build using the
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<option>-with-kerberos5</option> parameter, you'll need to modify the
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<filename>Makefile</filename> if you previously linked
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<application>OpenSSL</application> into the
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<application>Heimdal</application> build or the build will fail. The
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<application>OpenSSH</application> default expects
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<application>Heimdal</application> was built using the included
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<filename class='libraryfile'>libdes</filename> library instead of
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<application>OpenSSL</application>. Use the following command to modify
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the <filename>Makefile</filename>:</para>
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-->
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<para>If you linked <application>tcp_wrappers</application> into the
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build using the <option>--with-tcp-wrappers</option> parameter, ensure
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you add 127.0.0.1 to the sshd line in <filename>/etc/hosts.allow</filename>
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if you have a restrictive <filename>/etc/hosts.deny</filename> file, or the
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test suite will fail. To run the test suite, issue: <command>make -k
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tests</command>. The banner tests are known to fail.</para>
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<para>Now, as the <systemitem class="username">root</systemitem> user:</para>
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<screen role="root"><userinput>make install &&
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install -v -m755 -d /usr/share/doc/openssh-&openssh-version; &&
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install -v -m644 INSTALL LICENCE OVERVIEW README* WARNING.RNG \
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/usr/share/doc/openssh-&openssh-version;</userinput></screen>
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</sect2>
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<sect2 role="commands">
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<title>Command Explanations</title>
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<para><command>sed -i "s/lkrb5 -ldes/lkrb5/" configure</command>:
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This command fixes a build crash if you used the
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<option>--with-kerberos5</option> parameter and you built the
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<application>Heimdal</application> package in accordance with the BLFS
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instructions. The command is harmless in all other instances.</para>
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<para><parameter>--sysconfdir=/etc/ssh</parameter>: This prevents
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the configuration files from being installed in
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<filename class="directory">/usr/etc</filename>.</para>
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<para><parameter>--with-md5-passwords</parameter>: This is required
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if you made the changes recommended by the shadowpasswd_plus
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LFS hint on your SSH server when you installed the Shadow Password
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Suite or if you access a SSH server that authenticates by
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user passwords encrypted with md5.</para>
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<para><parameter>--libexecdir=/usr/lib/openssh</parameter>: This parameter
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changes the installation path of some programs to
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<filename class="directory">/usr/lib/openssh</filename> instead of
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<filename class="directory">/usr/libexec</filename>.</para>
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</sect2>
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<sect2 role="configuration">
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<title>Configuring OpenSSH</title>
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<sect3 id="openssh-config">
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<title>Config Files</title>
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<para><filename>~/.ssh/*</filename>,
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<filename>/etc/ssh/ssh_config</filename>, and
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<filename>/etc/ssh/sshd_config</filename></para>
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<indexterm zone="openssh openssh-config">
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<primary sortas="e-AA.ssh">~/.ssh/*</primary>
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</indexterm>
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<indexterm zone="openssh openssh-config">
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<primary sortas="e-etc-ssh-ssh_config">/etc/ssh/ssh_config</primary>
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</indexterm>
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<indexterm zone="openssh openssh-config">
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<primary sortas="e-etc-ssh-sshd_config">/etc/ssh/sshd_config</primary>
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</indexterm>
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<para>There are no required changes to any of these files. However,
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you may wish to view the <filename class='directory'>/etc/ssh/</filename>
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files and make any changes appropriate for the security of your system.
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One recommended change is that you disable
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<systemitem class='username'>root</systemitem> login via
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<command>ssh</command>. Execute the following command as the
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<systemitem class='username'>root</systemitem> user to disable
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<systemitem class='username'>root</systemitem> login via
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<command>ssh</command>:</para>
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<screen role="root"><userinput>echo "PermitRootLogin no" >> /etc/ssh/sshd_config</userinput></screen>
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<para>Additional configuration information can be found in the man
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pages for <command>sshd</command>, <command>ssh</command> and
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<command>ssh-agent</command>.</para>
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</sect3>
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<sect3 id="openssh-init">
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<title>Boot Script</title>
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<para>To start the SSH server at system boot, install the
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<filename>/etc/rc.d/init.d/sshd</filename> init script included
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in the <xref linkend="bootscripts"/> package.</para>
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<indexterm zone="openssh openssh-init">
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<primary sortas="f-sshd">sshd</primary>
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</indexterm>
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<screen role="root"><userinput>make install-sshd</userinput></screen>
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</sect3>
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</sect2>
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<sect2 role="content">
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<title>Contents</title>
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<segmentedlist>
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<segtitle>Installed Programs</segtitle>
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<segtitle>Installed Libraries</segtitle>
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<segtitle>Installed Directories</segtitle>
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<seglistitem>
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<seg>scp, sftp, sftp-server, slogin, ssh, sshd, ssh-add, ssh-agent,
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ssh-keygen, ssh-keyscan, and ssh-keysign</seg>
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<seg>None</seg>
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<seg>/etc/ssh, /var/lib/sshd and
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/usr/share/doc/openssh-&openssh-version;</seg>
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</seglistitem>
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</segmentedlist>
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<variablelist>
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<bridgehead renderas="sect3">Short Descriptions</bridgehead>
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<?dbfo list-presentation="list"?>
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<?dbhtml list-presentation="table"?>
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<varlistentry id="scp">
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<term><command>scp</command></term>
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<listitem>
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<para>is a file copy program that acts like <command>rcp</command>
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except it uses an encrypted protocol.</para>
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<indexterm zone="openssh scp">
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<primary sortas="b-scp">scp</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="sftp">
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<term><command>sftp</command></term>
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<listitem>
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<para>is an FTP-like program that works over
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SSH1 and SSH2 protocols.</para>
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<indexterm zone="openssh sftp">
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<primary sortas="b-sftp">sftp</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="sftp-server">
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<term><command>sftp-server</command></term>
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<listitem>
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<para>is an SFTP server subsystem.</para>
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<indexterm zone="openssh sftp-server">
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<primary sortas="b-sftp-server">sftp-server</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="slogin">
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<term><command>slogin</command></term>
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<listitem>
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<para>is a symlink to <command>ssh</command>.</para>
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<indexterm zone="openssh slogin">
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<primary sortas="g-slogin">slogin</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="ssh">
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<term><command>ssh</command></term>
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<listitem>
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<para>is an <command>rlogin</command>/<command>rsh</command>-like
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client program except it uses an encrypted protocol.</para>
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<indexterm zone="openssh ssh">
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<primary sortas="b-ssh">ssh</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="sshd">
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<term><command>sshd</command></term>
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<listitem>
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<para>is a daemon that listens for <command>ssh</command> login
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requests.</para>
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<indexterm zone="openssh sshd">
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<primary sortas="b-sshd">sshd</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="ssh-add">
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<term><command>ssh-add</command></term>
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<listitem>
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<para>is a tool which adds keys to the
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<command>ssh-agent</command>.</para>
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<indexterm zone="openssh ssh-add">
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<primary sortas="b-ssh-add">ssh-add</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="ssh-agent">
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<term><command>ssh-agent</command></term>
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<listitem>
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<para>is an authentication agent that can store private keys.</para>
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<indexterm zone="openssh ssh-agent">
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<primary sortas="b-ssh-agent">ssh-agent</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="ssh-keygen">
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<term><command>ssh-keygen</command></term>
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<listitem>
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<para>is a key generation tool.</para>
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<indexterm zone="openssh ssh-keygen">
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<primary sortas="b-ssh-keygen">ssh-keygen</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="ssh-keyscan">
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<term><command>ssh-keyscan</command></term>
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<listitem>
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<para>is a utility for gathering public host keys from a
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number of hosts.</para>
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<indexterm zone="openssh ssh-keyscan">
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<primary sortas="b-ssh-keyscan">ssh-keyscan</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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<varlistentry id="ssh-keysign">
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<term><command>ssh-keysign</command></term>
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<listitem>
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<para>is used by <command>ssh</command> to access the local host
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keys and generate the digital signature required during hostbased
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authentication with SSH protocol version 2.</para>
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<indexterm zone="openssh ssh-keysign">
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<primary sortas="b-ssh-keysign">ssh-keysign</primary>
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</indexterm>
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</listitem>
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</varlistentry>
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</variablelist>
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</sect2>
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</sect1>
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