White space fix only. Translators can ignore.
Sponsored by: iXsystems
This commit is contained in:
Dru Lavigne
parent
178e814996
commit
b41196460e
Notes:
svn2git
2020-12-08 03:00:23 +00:00
svn path=/head/; revision=44144
1 changed files with 223 additions and 218 deletions
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@ -104,20 +104,19 @@
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</indexterm>
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<para><firstterm>Routing</firstterm> is the mechanism that allows
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a system to find the network path to another system.
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A <firstterm>route</firstterm> is a
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defined pair of addresses which represent the <quote>destination</quote> and a
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a system to find the network path to another system. A
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<firstterm>route</firstterm> is a defined pair of addresses
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which represent the <quote>destination</quote> and a
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<quote>gateway</quote>. The route indicates that when trying
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to get to the specified destination, send the packets
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through the specified gateway. There are three
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types of destinations: individual hosts, subnets, and
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<quote>default</quote>. The <quote>default route</quote> is
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used if no other routes apply. There are also three
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types of gateways: individual hosts, interfaces, also called
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links, and Ethernet hardware
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to get to the specified destination, send the packets through
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the specified gateway. There are three types of destinations:
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individual hosts, subnets, and <quote>default</quote>. The
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<quote>default route</quote> is used if no other routes apply.
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There are also three types of gateways: individual hosts,
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interfaces, also called links, and Ethernet hardware
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(<acronym>MAC</acronym>) addresses. Known routes are stored in
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a routing table.</para>
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<para>This section provides an overview of routing basics. It
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then demonstrates how to configure a &os; system as a router and
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offers some troubleshooting tips.</para>
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@ -125,7 +124,8 @@
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<sect2 xml:id="network-routing-default">
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<title>Routing Basics</title>
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<para>To view the routing table of a &os; system, use &man.netstat.1;:</para>
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<para>To view the routing table of a &os; system, use
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&man.netstat.1;:</para>
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<screen>&prompt.user; <userinput>netstat -r</userinput>
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Routing tables
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@ -148,111 +148,120 @@ host2.example.com link#1 UC 0 0
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<varlistentry>
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<term>default</term>
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<listitem>
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<para>The first route in this table specifies the <literal>default</literal>
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route. When the local system needs to make a connection to a
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remote host, it checks the routing table to determine if a
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known path exists. If the remote host matches an entry in the
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table, the system checks to see if it
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can connect using the interface specified in that entry.</para>
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<para>The first route in this table specifies the
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<literal>default</literal> route. When the local system
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needs to make a connection to a remote host, it checks
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the routing table to determine if a known path exists.
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If the remote host matches an entry in the table, the
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system checks to see if it can connect using the
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interface specified in that entry.</para>
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<para>If the destination does not match an entry, or if all known
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paths fail, the system uses the entry for the
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default route. For hosts on a local area network, the
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<literal>Gateway</literal> field in the default route is set
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to the system which has a direct connection to
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the Internet. When reading this entry, verify that the
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<literal>Flags</literal> column indicates that the gateway is
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usable (<literal>UG</literal>).</para>
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<para>If the destination does not match an entry, or if
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all known paths fail, the system uses the entry for the
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default route. For hosts on a local area network, the
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<literal>Gateway</literal> field in the default route is
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set to the system which has a direct connection to the
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Internet. When reading this entry, verify that the
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<literal>Flags</literal> column indicates that the
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gateway is usable (<literal>UG</literal>).</para>
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<para>The default route for a machine which itself is
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functioning as the gateway to the outside world will be the
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gateway machine at the Internet Service Provider
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(<acronym>ISP</acronym>).</para>
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</listitem>
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</varlistentry>
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<para>The default route for a machine which itself is
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functioning as the gateway to the outside world will be
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the gateway machine at the Internet Service Provider
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(<acronym>ISP</acronym>).</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>localhost</term>
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<listitem>
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<para>The second route is the <literal>localhost</literal> route.
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The interface specified in the <literal>Netif</literal> column
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for <literal>localhost</literal> is <filename>lo0</filename>,
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also known as the loopback device. This indicates that all
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traffic for this destination should be internal, rather than sending it
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out over the network.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>localhost</term>
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<listitem>
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<para>The second route is the <literal>localhost</literal>
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route. The interface specified in the
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<literal>Netif</literal> column for
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<literal>localhost</literal> is
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<filename>lo0</filename>, also known as the loopback
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device. This indicates that all traffic for this
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destination should be internal, rather than sending it
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out over the network.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>MAC address</term>
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<listitem>
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<para>The addresses beginning with <systemitem
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class="etheraddress">0:e0:</systemitem> are <acronym>MAC</acronym>
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addresses. &os; will automatically identify any hosts,
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<systemitem>test0</systemitem> in the example, on the local
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Ethernet and add a route for that host over the Ethernet
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interface, <filename>re0</filename>. This type of route has a
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timeout, seen in the <literal>Expire</literal> column, which
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is used if the host does not respond in a specific amount of
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time. When this happens, the route to this host will be
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automatically deleted. These hosts are identified using the
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Routing Information Protocol (<acronym>RIP</acronym>), which
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calculates routes to local hosts based upon a shortest path
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determination.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>MAC address</term>
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<listitem>
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<para>The addresses beginning with <systemitem
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class="etheraddress">0:e0:</systemitem> are
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<acronym>MAC</acronym> addresses. &os; will
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automatically identify any hosts,
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<systemitem>test0</systemitem> in the example, on the
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local Ethernet and add a route for that host over the
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Ethernet interface, <filename>re0</filename>. This type
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of route has a timeout, seen in the
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<literal>Expire</literal> column, which is used if the
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host does not respond in a specific amount of time.
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When this happens, the route to this host will be
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automatically deleted. These hosts are identified using
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the Routing Information Protocol
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(<acronym>RIP</acronym>), which calculates routes to
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local hosts based upon a shortest path
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determination.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>subnet</term>
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<listitem>
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<para>&os; will automatically add subnet routes for the local subnet.
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In this example, <systemitem class="ipaddress">10.20.30.255</systemitem> is the
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broadcast address for the subnet <systemitem
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class="ipaddress">10.20.30</systemitem> and <systemitem
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class="fqdomainname">example.com</systemitem> is the domain
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name associated with that subnet. The designation
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<literal>link#1</literal> refers to the first Ethernet card in
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the machine.</para>
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<varlistentry>
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<term>subnet</term>
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<listitem>
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<para>&os; will automatically add subnet routes for the
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local subnet. In this example, <systemitem
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class="ipaddress">10.20.30.255</systemitem> is the
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broadcast address for the subnet <systemitem
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class="ipaddress">10.20.30</systemitem> and
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<systemitem
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class="fqdomainname">example.com</systemitem> is the
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domain name associated with that subnet. The
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designation <literal>link#1</literal> refers to the
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first Ethernet card in the machine.</para>
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<para>Local network hosts and local subnets have their routes
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automatically configured by a daemon called &man.routed.8;.
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If it is not running, only routes which are statically defined
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by the administrator will exist.</para>
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</listitem>
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</varlistentry>
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<para>Local network hosts and local subnets have their
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routes automatically configured by a daemon called
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&man.routed.8;. If it is not running, only routes which
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are statically defined by the administrator will
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exist.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>host</term>
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<listitem>
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<para>The <literal>host1</literal> line refers to the host
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by its Ethernet address. Since it is the sending host, &os;
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knows to use the loopback interface
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(<filename>lo0</filename>) rather than the Ethernet
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interface.</para>
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<varlistentry>
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<term>host</term>
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<listitem>
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<para>The <literal>host1</literal> line refers to the host
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by its Ethernet address. Since it is the sending host,
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&os; knows to use the loopback interface
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(<filename>lo0</filename>) rather than the Ethernet
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interface.</para>
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<para>The two <literal>host2</literal> lines represent aliases
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which were created using &man.ifconfig.8;. The
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<literal>=></literal> symbol after the
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<filename>lo0</filename> interface says that an alias has been
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set in addition to the loopback address. Such routes only
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show up on the host that supports the alias and all other hosts
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on the local network will have a
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<literal>link#1</literal> line for such routes.</para>
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</listitem>
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</varlistentry>
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<para>The two <literal>host2</literal> lines represent
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aliases which were created using &man.ifconfig.8;. The
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<literal>=></literal> symbol after the
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<filename>lo0</filename> interface says that an alias
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has been set in addition to the loopback address. Such
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routes only show up on the host that supports the alias
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and all other hosts on the local network will have a
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<literal>link#1</literal> line for such routes.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>224</term>
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<listitem>
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<para>The final line (destination subnet <systemitem
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class="ipaddress">224</systemitem>) deals with
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multicasting.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<varlistentry>
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<term>224</term>
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<listitem>
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<para>The final line (destination subnet <systemitem
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class="ipaddress">224</systemitem>) deals with
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multicasting.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>Various attributes of each route can be seen in
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the <literal>Flags</literal> column. <xref linkend="routeflags"/>
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<para>Various attributes of each route can be seen in the
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<literal>Flags</literal> column. <xref linkend="routeflags"/>
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summarizes some of these flags and their meanings:</para>
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<table xml:id="routeflags" frame="none" pgwide="1">
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@ -274,15 +283,14 @@ host2.example.com link#1 UC 0 0
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<row>
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<entry>H</entry>
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<entry>The route destination is a single
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host.</entry>
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<entry>The route destination is a single host.</entry>
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</row>
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<row>
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<entry>G</entry>
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<entry>Send anything for this destination on to
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this gateway, which will figure out from there
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where to send it.</entry>
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<entry>Send anything for this destination on to this
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gateway, which will figure out from there where to
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send it.</entry>
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</row>
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<row>
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@ -292,16 +300,15 @@ host2.example.com link#1 UC 0 0
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<row>
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<entry>C</entry>
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<entry>Clones a new route based upon this
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route for machines to connect to. This type of route
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is normally used for local networks.</entry>
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<entry>Clones a new route based upon this route for
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machines to connect to. This type of route is
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normally used for local networks.</entry>
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</row>
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<row>
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<entry>W</entry>
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<entry>The route was
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auto-configured based upon a local area network
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(clone) route.</entry>
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<entry>The route was auto-configured based upon a local
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area network (clone) route.</entry>
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</row>
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<row>
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@ -326,7 +333,7 @@ host2.example.com link#1 UC 0 0
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<para>Note that manually added routes will not survive a reboot.
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For more information on manual manipulation of network
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routing tables, refer to &man.route.8;.</para>
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routing tables, refer to &man.route.8;.</para>
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</sect2>
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<sect2 xml:id="network-static-routes">
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@ -352,20 +359,20 @@ host2.example.com link#1 UC 0 0
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<para>A &os; system can be configured as the default gateway, or
|
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router, for a network if it is a dual-homed system. A
|
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dual-homed system is a host which resides on at least two
|
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different networks. Typically, each network is connected to a separate
|
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network interface, though <acronym>IP</acronym> aliasing can
|
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be used to bind multiple addresses, each on a different
|
||||
subnet, to one physical interface.</para>
|
||||
different networks. Typically, each network is connected to a
|
||||
separate network interface, though <acronym>IP</acronym>
|
||||
aliasing can be used to bind multiple addresses, each on a
|
||||
different subnet, to one physical interface.</para>
|
||||
|
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<indexterm>
|
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<primary>router</primary>
|
||||
</indexterm>
|
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|
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<para>In order for the system to forward packets between
|
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interfaces, &os; must be configured as a router. Internet standards and good
|
||||
engineering practice prevent the &os; Project from enabling
|
||||
this feature by default, but it can be configured to start at boot
|
||||
by adding this line to
|
||||
interfaces, &os; must be configured as a router. Internet
|
||||
standards and good engineering practice prevent the &os;
|
||||
Project from enabling this feature by default, but it can be
|
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configured to start at boot by adding this line to
|
||||
<filename>/etc/rc.conf</filename>:</para>
|
||||
|
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<programlisting>gateway_enable="YES" # Set to YES if this host will be a gateway</programlisting>
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|
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@ -387,31 +394,30 @@ host2.example.com link#1 UC 0 0
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|
||||
<para>The routing table of a router needs additional routes so
|
||||
it knows how to reach other networks. Routes can be either
|
||||
added manually using
|
||||
static routes or routes can be automatically learned using a routing protocol.
|
||||
Static routes are appropriate for small networks and this
|
||||
section describes how to add a static routing entry for a
|
||||
small network.</para>
|
||||
added manually using static routes or routes can be
|
||||
automatically learned using a routing protocol. Static routes
|
||||
are appropriate for small networks and this section describes
|
||||
how to add a static routing entry for a small network.</para>
|
||||
|
||||
<note>
|
||||
<note>
|
||||
<para>For large networks, static routes quickly become
|
||||
unscalable. &os; comes with the standard <acronym>BSD</acronym> routing daemon
|
||||
&man.routed.8;, which provides the routing protocols <acronym>RIP</acronym>, versions
|
||||
1 and 2, and <acronym>IRDP</acronym>. Support for the
|
||||
<acronym>BGP</acronym> and <acronym>OSPF</acronym>
|
||||
routing protocols can be installed using the
|
||||
<package>net/zebra</package> package or
|
||||
port.</para>
|
||||
unscalable. &os; comes with the standard
|
||||
<acronym>BSD</acronym> routing daemon &man.routed.8;, which
|
||||
provides the routing protocols <acronym>RIP</acronym>,
|
||||
versions 1 and 2, and <acronym>IRDP</acronym>. Support for
|
||||
the <acronym>BGP</acronym> and <acronym>OSPF</acronym>
|
||||
routing protocols can be installed using the
|
||||
<package>net/zebra</package> package or port.</para>
|
||||
</note>
|
||||
|
||||
<para>Consider the following network:</para>
|
||||
<para>Consider the following network:</para>
|
||||
|
||||
<mediaobject>
|
||||
<imageobject>
|
||||
<imagedata fileref="advanced-networking/static-routes"/>
|
||||
</imageobject>
|
||||
<mediaobject>
|
||||
<imageobject>
|
||||
<imagedata fileref="advanced-networking/static-routes"/>
|
||||
</imageobject>
|
||||
|
||||
<textobject>
|
||||
<textobject>
|
||||
<literallayout class="monospaced">
|
||||
INTERNET
|
||||
| (10.0.0.1/24) Default Router to Internet
|
||||
|
|
@ -435,23 +441,22 @@ host2.example.com link#1 UC 0 0
|
|||
| 192.168.2.1/24
|
||||
|
|
||||
Internal Net 2</literallayout>
|
||||
</textobject>
|
||||
</mediaobject>
|
||||
</textobject>
|
||||
</mediaobject>
|
||||
|
||||
<para>In this scenario, <systemitem>RouterA</systemitem> is a
|
||||
&os; machine that is acting as a router to the rest of the
|
||||
Internet. It has a default route set to <systemitem
|
||||
class="ipaddress">10.0.0.1</systemitem> which allows it to
|
||||
connect with the outside world.
|
||||
<systemitem>RouterB</systemitem> is already configured
|
||||
to use <systemitem
|
||||
class="ipaddress">192.168.1.1</systemitem> as its default
|
||||
gateway.</para>
|
||||
<para>In this scenario, <systemitem>RouterA</systemitem> is a
|
||||
&os; machine that is acting as a router to the rest of the
|
||||
Internet. It has a default route set to <systemitem
|
||||
class="ipaddress">10.0.0.1</systemitem> which allows it to
|
||||
connect with the outside world.
|
||||
<systemitem>RouterB</systemitem> is already configured to use
|
||||
<systemitem class="ipaddress">192.168.1.1</systemitem> as its
|
||||
default gateway.</para>
|
||||
|
||||
<para>Before adding any static routes, the routing table on <systemitem>RouterA</systemitem>
|
||||
looks like this:</para>
|
||||
<para>Before adding any static routes, the routing table on
|
||||
<systemitem>RouterA</systemitem> looks like this:</para>
|
||||
|
||||
<screen>&prompt.user; <userinput>netstat -nr</userinput>
|
||||
<screen>&prompt.user; <userinput>netstat -nr</userinput>
|
||||
Routing tables
|
||||
|
||||
Internet:
|
||||
|
|
@ -461,56 +466,55 @@ default 10.0.0.1 UGS 0 49378 xl0
|
|||
10.0.0.0/24 link#1 UC 0 0 xl0
|
||||
192.168.1.0/24 link#2 UC 0 0 xl1</screen>
|
||||
|
||||
<para>With the current routing table,
|
||||
<systemitem>RouterA</systemitem>
|
||||
does not have a route to the <systemitem
|
||||
class="ipaddress">192.168.2.0/24</systemitem> network. The
|
||||
following command adds the <literal>Internal Net 2</literal> network to
|
||||
<systemitem>RouterA</systemitem>'s routing table using
|
||||
<systemitem class="ipaddress">192.168.1.2</systemitem> as
|
||||
the next hop:</para>
|
||||
<para>With the current routing table,
|
||||
<systemitem>RouterA</systemitem> does not have a route to the
|
||||
<systemitem class="ipaddress">192.168.2.0/24</systemitem>
|
||||
network. The following command adds the <literal>Internal Net
|
||||
2</literal> network to <systemitem>RouterA</systemitem>'s
|
||||
routing table using <systemitem
|
||||
class="ipaddress">192.168.1.2</systemitem> as the next
|
||||
hop:</para>
|
||||
|
||||
<screen>&prompt.root; <userinput>route add -net 192.168.2.0/24 192.168.1.2</userinput></screen>
|
||||
<screen>&prompt.root; <userinput>route add -net 192.168.2.0/24 192.168.1.2</userinput></screen>
|
||||
|
||||
<para>Now, <systemitem>RouterA</systemitem> can reach any host
|
||||
on the <systemitem
|
||||
class="ipaddress">192.168.2.0/24</systemitem>
|
||||
network. However, the routing information will not
|
||||
persist if the &os; system reboots. If a static route needs
|
||||
to be persistent, add it to
|
||||
<filename>/etc/rc.conf</filename>:</para>
|
||||
<para>Now, <systemitem>RouterA</systemitem> can reach any host
|
||||
on the <systemitem
|
||||
class="ipaddress">192.168.2.0/24</systemitem> network.
|
||||
However, the routing information will not persist if the &os;
|
||||
system reboots. If a static route needs to be persistent, add
|
||||
it to <filename>/etc/rc.conf</filename>:</para>
|
||||
|
||||
<programlisting># Add Internal Net 2 as a persistent static route
|
||||
<programlisting># Add Internal Net 2 as a persistent static route
|
||||
static_routes="internalnet2"
|
||||
route_internalnet2="-net 192.168.2.0/24 192.168.1.2"</programlisting>
|
||||
|
||||
<para>The <literal>static_routes</literal> configuration
|
||||
variable is a list of strings separated by a space, where
|
||||
each string references a route name. The variable
|
||||
<literal>route_internalnet2</literal>
|
||||
contains the static route for that route name.</para>
|
||||
<para>The <literal>static_routes</literal> configuration
|
||||
variable is a list of strings separated by a space, where
|
||||
each string references a route name. The variable
|
||||
<literal>route_internalnet2</literal> contains the static
|
||||
route for that route name.</para>
|
||||
|
||||
<para>Using more than one string in
|
||||
<literal>static_routes</literal> creates multiple static
|
||||
routes. The following shows an example of adding static
|
||||
routes for the <systemitem
|
||||
class="ipaddress">192.168.0.0/24</systemitem> and
|
||||
<systemitem class="ipaddress">192.168.1.0/24</systemitem>
|
||||
networks:</para>
|
||||
<para>Using more than one string in
|
||||
<literal>static_routes</literal> creates multiple static
|
||||
routes. The following shows an example of adding static
|
||||
routes for the <systemitem
|
||||
class="ipaddress">192.168.0.0/24</systemitem> and
|
||||
<systemitem class="ipaddress">192.168.1.0/24</systemitem>
|
||||
networks:</para>
|
||||
|
||||
<programlisting>static_routes="net1 net2"
|
||||
<programlisting>static_routes="net1 net2"
|
||||
route_net1="-net 192.168.0.0/24 192.168.0.1"
|
||||
route_net2="-net 192.168.1.0/24 192.168.1.1"</programlisting>
|
||||
</sect2>
|
||||
|
||||
<sect2 xml:id="network-routing-troubleshooting">
|
||||
<sect2 xml:id="network-routing-troubleshooting">
|
||||
<title>Troubleshooting</title>
|
||||
|
||||
<para>When an address space is assigned to a network, the
|
||||
service provider configures their routing tables so that all
|
||||
traffic for the network will be sent to the link for the
|
||||
site. But how do external sites know to send their packets
|
||||
to the network's <acronym>ISP</acronym>?</para>
|
||||
traffic for the network will be sent to the link for the site.
|
||||
But how do external sites know to send their packets to the
|
||||
network's <acronym>ISP</acronym>?</para>
|
||||
|
||||
<para>There is a system that keeps track of all assigned
|
||||
address spaces and defines their point of connection to the
|
||||
|
|
@ -530,17 +534,18 @@ route_net2="-net 192.168.1.0/24 192.168.1.1"</programlisting>
|
|||
<primary>&man.traceroute.8;</primary>
|
||||
</indexterm>
|
||||
|
||||
<para>Sometimes, there is a problem with route propagation
|
||||
and some sites are unable to connect. Perhaps the most
|
||||
useful command for trying to figure out where routing is
|
||||
breaking down is <command>traceroute</command>. It is useful when
|
||||
<para>Sometimes, there is a problem with route propagation and
|
||||
some sites are unable to connect. Perhaps the most useful
|
||||
command for trying to figure out where routing is breaking
|
||||
down is <command>traceroute</command>. It is useful when
|
||||
<command>ping</command> fails.</para>
|
||||
|
||||
<para>When using <command>traceroute</command>, include the address of the
|
||||
remote host to connect to. The output will show the gateway
|
||||
hosts along the path of the attempt, eventually either
|
||||
reaching the target host, or terminating because of a lack of
|
||||
connection. For more information, refer to &man.traceroute.8;.</para>
|
||||
<para>When using <command>traceroute</command>, include the
|
||||
address of the remote host to connect to. The output will
|
||||
show the gateway hosts along the path of the attempt,
|
||||
eventually either reaching the target host, or terminating
|
||||
because of a lack of connection. For more information, refer
|
||||
to &man.traceroute.8;.</para>
|
||||
</sect2>
|
||||
|
||||
<sect2 xml:id="network-routing-multicast">
|
||||
|
|
@ -556,29 +561,29 @@ route_net2="-net 192.168.1.0/24 192.168.1.1"</programlisting>
|
|||
|
||||
<para>&os; natively supports both multicast applications and
|
||||
multicast routing. Multicast applications do not require any
|
||||
special configuration in order to
|
||||
run on &os;. Support for multicast routing requires that the
|
||||
following option
|
||||
be compiled into a custom kernel:</para>
|
||||
special configuration in order to run on &os;. Support for
|
||||
multicast routing requires that the following option be
|
||||
compiled into a custom kernel:</para>
|
||||
|
||||
<programlisting>options MROUTING</programlisting>
|
||||
|
||||
<para>The multicast routing daemon,
|
||||
<application>mrouted</application> can be installed
|
||||
using the <package>net/mrouted</package> package or port.
|
||||
This daemon implements
|
||||
the <acronym>DVMRP</acronym> multicast routing protocol and is
|
||||
configured by editing <filename>/usr/local/etc/mrouted.conf</filename>
|
||||
in order to set up the tunnels and <acronym>DVMRP</acronym>.
|
||||
The installation of <application>mrouted</application> also installs
|
||||
<application>map-mbone</application> and
|
||||
<application>mrouted</application> can be installed using the
|
||||
<package>net/mrouted</package> package or port. This daemon
|
||||
implements the <acronym>DVMRP</acronym> multicast routing
|
||||
protocol and is configured by editing
|
||||
<filename>/usr/local/etc/mrouted.conf</filename> in order to
|
||||
set up the tunnels and <acronym>DVMRP</acronym>. The
|
||||
installation of <application>mrouted</application> also
|
||||
installs <application>map-mbone</application> and
|
||||
<application>mrinfo</application>, as well as their associated
|
||||
man pages. Refer to these for configuration examples.</para>
|
||||
|
||||
<note>
|
||||
<para><acronym>DVMRP</acronym> has largely been replaced by the
|
||||
<acronym>PIM</acronym> protocol in many
|
||||
multicast installations. Refer to &man.pim.4; for more information.</para>
|
||||
<para><acronym>DVMRP</acronym> has largely been replaced by
|
||||
the <acronym>PIM</acronym> protocol in many multicast
|
||||
installations. Refer to &man.pim.4; for more
|
||||
information.</para>
|
||||
</note>
|
||||
</sect2>
|
||||
</sect1>
|
||||
|
|
|
|||
Loading…
Reference in a new issue