394 lines
5.7 KiB
HTML
394 lines
5.7 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Setup</TITLE
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
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TITLE="Bridging mini-HOWTO"
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HREF="index.html"><LINK
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TITLE="Bridging mini-HOWTO"
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HREF="index.html"><LINK
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TITLE="Common Problems"
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HREF="x72.html"></HEAD
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>Bridging mini-HOWTO</TH
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>Prev</A
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="AEN23">1. Setup</H1
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><P
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> <P
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></P
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><UL
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><LI
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><P
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>Get Bridge Config:
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<A
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HREF="ftp://ftp.tux.org/people/alan-cox/BRCFG.tgz"
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TARGET="_top"
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> BRCFG.tgz</A
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>
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</P
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></LI
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><LI
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><P
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>BRCFG may also be found at:
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<A
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HREF="http://coledd.com/networking/bridge/"
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TARGET="_top"
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> http://coledd.com/networking/bridge</A
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>
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</P
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></LI
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><LI
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><P
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>Enable multiple ethernet devices on your machine by
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adding this line to your <TT
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CLASS="FILENAME"
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>/etc/lilo.conf</TT
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>,
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and re-run <SPAN
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CLASS="APPLICATION"
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>lilo</SPAN
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>:
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<TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>append = "ether=0,0,eth1"</PRE
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></FONT
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></TD
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></TR
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></TABLE
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>
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</P
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><P
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>If you have three interfaces on your bridge, use this line instead:
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<TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>append = "ether=0,0,eth1 ether=0,0,eth2"</PRE
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></FONT
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></TD
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></TR
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></TABLE
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>
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</P
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><P
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>More interfaces can be found by adding more ether statements.
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By default a stock Linux kernel probes for a single ethercard,
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and once one is found the probe ceases. The above append statement
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tells the kernel to keep probing for more ethernet devices after the
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first one is found.
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Alternatively, the boot parameter can be used instead:
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<TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>linux ether=0,0,eth1</PRE
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></FONT
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></TD
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></TR
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></TABLE
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>
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</P
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><P
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>Or, with 3 interfaces, use:
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<TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>linux ether=0,0,eth1 ether=0,0,eth2</PRE
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></FONT
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></TD
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></TR
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></TABLE
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>
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</P
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></LI
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><LI
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><P
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>Recompile the kernel with <TT
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CLASS="ENVAR"
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>BRIDGING</TT
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> enabled.
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</P
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></LI
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><LI
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><P
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>A bridge should not have an IP address.
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It CAN, but a plain bridge doesn't need one.
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To remove the IP address from your bridge, go to
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<TT
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CLASS="FILENAME"
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>/etc/sysconfig/network-scripts/</TT
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> (for a RedHat system)
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and copy <TT
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CLASS="FILENAME"
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>ifcfg-lo0</TT
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> to <TT
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CLASS="FILENAME"
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>ifcfg-eth0</TT
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> &
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<TT
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CLASS="FILENAME"
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>ifcfg-eth1</TT
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>.
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In these two new files, change the line containing
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<TT
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CLASS="USERINPUT"
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><B
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>DEVICE=lo</B
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></TT
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> to <TT
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CLASS="USERINPUT"
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><B
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>DEVICE=eth0</B
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></TT
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>
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and <TT
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CLASS="USERINPUT"
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><B
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>DEVICE=eth1</B
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></TT
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>.
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Since other distributions may deviate from this, you may need to refer to additional
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documentation.
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If there are more than 2 interfaces to this bridge,
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be sure to make the corresponding configurations to those, as well.
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</P
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></LI
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><LI
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><P
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>Reboot so you are running the new kernel with <TT
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CLASS="ENVAR"
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>BRIDGING</TT
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> in it,
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and also to make sure that an IP addresses are not bound to the
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network interfaces.
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</P
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></LI
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><LI
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><P
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>Once the system is backed up, put the ethernet cards into promiscuous mode,
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so they will look at every packet that passes by its interface:
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<TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>ifconfig eth0 promisc ; ifconfig eth1 promisc</PRE
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></FONT
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></TD
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></TR
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></TABLE
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>
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All interfaces which are connected to network segments to be bridged
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are to be put into promiscuous mode.
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</P
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></LI
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><LI
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><P
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>Turn bridging ON using the <SPAN
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CLASS="APPLICATION"
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>brcfg</SPAN
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> program:
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<TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>brcfg -ena</PRE
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></FONT
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></TD
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></TR
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></TABLE
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>
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</P
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></LI
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><LI
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><P
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>Verify that there is different traffic on each interface:
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<TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="90%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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>tcpdump -i eth0 (in one window)
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tcpdump -i eth1 (in another window)
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</PRE
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></FONT
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></TD
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></TR
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></TABLE
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>
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</P
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></LI
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><LI
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><P
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>Run a sniffer or <SPAN
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CLASS="APPLICATION"
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>tcpdump</SPAN
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> on another machine
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to verify the bridge is separating the segment correctly.
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</P
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></LI
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></UL
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></P
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="100%"
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CELLSPACING="0"
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="index.html"
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>Prev</A
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ALIGN="center"
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VALIGN="top"
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HREF="index.html"
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>Home</A
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HREF="x72.html"
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>Next</A
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VALIGN="top"
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>Bridging mini-HOWTO</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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> </TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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>Common Problems</TD
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