icmp-redirects, hung connection, tcpdump
ja at ssi.bg
Mon Jan 15 09:20:20 GMT 2001
On Sun, 14 Jan 2001, Joseph Mack wrote:
> On Sun, 14 Jan 2001, Julian Anastasov wrote:
> > > Is this the problem being addressed here? i.e.
> > > so that people can have their real-servers and client on the same network.
> hmm, I tested this way back in the stone age of LVS and found that turning
> off redirects didn't work (I put it in the HOWTO even). Of course I didn't
> record exactly what I did. Maybe I only turned off redirects for each
> device, rather than running the separate instructions for all, default and
> What's the difference between all, default and eth0?
When the kernel needs to check for one feature (send_redirects for
example) it uses such calls: if (IN_DEV_TX_REDIRECTS(in_dev)) ...
These macros are defined in /usr/src/linux/include/linux/inetdevice.h
The macro returns a value using expression from all/<var> and <dev>/<var>
So, these macros check for example for:
all/send_redirects || eth0/send_redirects
all/hidden && eth0/hidden
when you create eth0 for first time using ifconfig eth0 ... up
default/send_redirects is copied to eth0/send_redirects from the
kernel, internally. I.e. default/ contains the initial values
the device inherits when it is created. This is the safest way a
device to appear with correct conf/<dev>/ values.
When we put value in all/<var> you can assume that we set the <var>
for all devices in this way:
all/<var> the macro returns:
for && 0 0
for && 1 the value from <dev>/<var>
for || 0 the value from <dev>/<var>
for || 1 1
This scheme allows the different devices to have different values
for their vars. For example, if we set 0 to all/send_redirects, the 3th
line applies to the values, i.e. the result from the macro is the real
value in <dev>/send_redirects. If we set 1 to all/send_redirects
according to the 4th line, the macro always returns 1 regardless
of the <dev>/send_redirects
> Joseph Mack mack at ncifcrf.gov
Julian Anastasov <ja at ssi.bg>
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