78 lines
2.8 KiB
HTML
78 lines
2.8 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
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<TITLE>Wireless Howto: Appendix A - Netmask 255.255.255.255, proxy arp and bridging </TITLE>
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<HR>
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<H2><A NAME="s10">10. Appendix A - Netmask 255.255.255.255, proxy arp and bridging </A></H2>
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<P>Here we view some Linux advantages in Wireless Internetworking.
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<P>Linux let you specify a netmask like 255.255.255.255 for an interface which
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can help you assign IP addresses in to any interface you want, for example
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one in eth0, another in eth1 and so on...
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<P>This has not particularly side-effects.
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<P>In addition you have proxy arp setting under /proc/sys/net/ipv4/conf/ethx/proxy_arp
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where ethx if your interface.
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<P>If you "echo 1 > proxy_arp" you enable proxy_arp for that
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interface while with "echo 0 > proxy_arp" you disable it.
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<P>What's proxy_arp? Quickly proxy arp help you when you want a router answer
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to an ARP request if the destination address is in another interface of the
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linux router.
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<P>Example:
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<P>
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<PRE>
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192.168.1.1 ---- 192.168.1.2 Linux router 192.168.2.2 ----192.168.2.1
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</PRE>
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<P>To get this example working you should:
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<P>
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<PRE>
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Without proxy-arp
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</PRE>
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<P>
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<OL>
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<LI>In 192.168.1.1 host to set 192.168.1.2 as gateway </LI>
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<LI>In 192.168.2.1 host to set 192.168.2.2 as gateway </LI>
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<LI>pinging with success from any edge. </LI>
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</OL>
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<P>
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<PRE>
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With proxy-arp
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</PRE>
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<P>
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<OL>
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<LI>In 192.168.1.1 host to set 192.168.1.2 as gateway </LI>
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<LI>do not set gateway for 192.168.2.1 host but enable proxy_arp for right
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interface of the router. </LI>
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<LI>pinging with success from any edge </LI>
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</OL>
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<P>Proxy-arp in 2. case let the linux router answer when you ping from 192.168.2.1
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host, saying that it has the 192.168.1.1 host so it can answer for it. After,
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when the source start sending ICMP packet, Linux router knows that it have
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to redirect it to the real host 192.168.1.1
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<P>In Wireless network proxy arp can help you if you have many Linux boxes
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that acts as IP Forwarders and you wouldn't set to all hosts a number of static
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route.
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<P>You also can experiment Linux bridging in Wireless network:
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<P>
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<OL>
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<LI>install a recent stable kernel </LI>
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<LI>download good bridge utils at
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<A HREF="http://openrock.net/bridge">http link</A> or
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<A HREF="ftp://openrock.net/bridge">ftp link</A> </LI>
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</OL>
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<P>Bridging should be more simple to manage.
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<HR>
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