Difference between revisions of "Ip forward"

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You might have noticed that /proc/sys/net/ipv4/ip_forward keeps getting reset to 0.  If you go into
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You might have noticed that /proc/sys/net/ipv4/ip_forward keeps getting reset to 0.   
/etc/network/options and change the line  
+
 
 +
There are three places I've found that cause this to happen.  First is /etc/network/options. Go
 +
in there and change the line  
 
<pre>ip_forward=no
 
<pre>ip_forward=no
 
</pre> to  
 
</pre> to  
 
<pre>
 
<pre>
 
ip_forward=yes
 
ip_forward=yes
</pre> the problem seems to go away.
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</pre>  
 +
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Next is /etc/pmnetconfig/if-down.  Comment out the lines
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 +
<pre>
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  ${LOG} "${ECHO} 0 >/proc/sys/net/ipv4/ip_forward"
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  ${ECHO} 0 >/proc/sys/net/ipv4/ip_forward
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</pre>
 +
 
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Last and not least, is the binary /usr/bin/PmNetConfigManager.  First, make a fake place for it to write to
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 +
<pre>
 +
mount -o remount,rw /
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mkdir /media/cryptofs/fake/sys/net/ipv4/ip_forward
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ln -s /media/cryptofs/fake /fake
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mount -o remount,ro /
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</pre>
 +
 
 +
Next, patch /usr/bin/PmNetConfigManager so it writes to /fake/sys/net/ipv4/ip_forward instead of /proc/sys/net/ipv4/ip_forward.  Just open it up in a hex editor, find that path, and change "proc" to "fake".  Make sure you only change those four bytes.

Revision as of 23:58, 1 March 2010

You might have noticed that /proc/sys/net/ipv4/ip_forward keeps getting reset to 0.

There are three places I've found that cause this to happen. First is /etc/network/options. Go in there and change the line

ip_forward=no

to

ip_forward=yes

Next is /etc/pmnetconfig/if-down. Comment out the lines

   ${LOG} "${ECHO} 0 >/proc/sys/net/ipv4/ip_forward"
   ${ECHO} 0 >/proc/sys/net/ipv4/ip_forward

Last and not least, is the binary /usr/bin/PmNetConfigManager. First, make a fake place for it to write to

mount -o remount,rw / 
mkdir /media/cryptofs/fake/sys/net/ipv4/ip_forward
ln -s /media/cryptofs/fake /fake
mount -o remount,ro /

Next, patch /usr/bin/PmNetConfigManager so it writes to /fake/sys/net/ipv4/ip_forward instead of /proc/sys/net/ipv4/ip_forward. Just open it up in a hex editor, find that path, and change "proc" to "fake". Make sure you only change those four bytes.