Route cache performance under stress

Please CC me on any replies:

The suggested code here is problematic.

   RND1 = random_generated_at_start_time() ;
   RND2 = random_generated_at_start_time() ;
   /* RND2 may be 0 or equal to RND1, all cases seem OK */
   x = (RND1 - saddr) ^ (RND1 - daddr) ^ (RND2 + saddr + daddr);
   reduce(x)

For instance, if the table is assumed to have size N, bucket collisions can be generated by:

saddr=daddr= k*N for all k.

Or, a different attack, if I assume that reduce(x) determines the bucket by masking off, say, the lowest 12 bits, then:

saddr=0xXXXXXAAA
daddr=0xYYYYYBBB

Where, XXX, YYY are anything, AAA, BBB are arbitrarily chosen.

Now, lets look at the various terms:
(RND1 - saddr) = 0xUUUUUCCC
(RND1 - daddr) = 0xUUUUUDDD
(RND2 + saddr + daddr) = 0xUUUUUEEE

The U's are all unknown, but the CCC, DDD, and EEE---the only thing that we care about---are constant. Thus, the lowest 12 bits of x will be constant. If those are the only bits that are used, then the attacker has complete freedom to forge the highest 20 bits of saddr and daddr.

With that function, you'd probably be better off masking off the high order bits. At least there's a chance of a carry from the UUUU's propagating into the bits you mask off.

I'm rusty with statistical analysis of cryptographic algorithms, but I suspect demons may be lurking from that avenue too.

What might work better is to have a good universal hash function, h, then do:

h_k(saddr) - h_k(daddr)

Perhaps the simplest is:

h_k(x) = x * k (mod P)

where P is a prime, and $ 0<= k < P$ is a random variable determined at bootup.

Scott

Hi everybody,

I am a newbie to Linux. I have a problem. I had Win 2K Pro installed on my PC. When I got Red Hat Linux 8.0 installed on it, the it showed "Unsupported VGA card", but the rest of the installation went fine. Now, I can log in to Linux, and only the command line is seen. When I enter the "startx" command, it gives some big error.

I have an ASUS P4SDR-VM motherboard with onboard VGA. Probably it is not supported by Red Hat. What do I do to get KDE/GNOME desktops working ? What exactly should I look for - is it the display drivers or RPMs ? Can I get anything from www.kernel.org ? Somebody told me that nVidia's nForce or gForce drivers should work for ASUS motherboard. Is that true ? In ASUS's website, I can see display drivers for download, for Red Hat Linux 7.3. Will those also work for 8.0 ? Are the display drivers specific to the motherboard make, or the Linux distro and version ?

I am quite confused and would really appreciate a detailed reply.

Thanking you all in anticipation.

With kind regards,
Pratyush Joshi

This question is more appropriate for a RedHat mailing list.

John.

You might try here:

http://www.winischhofer.net/sis/

But note that I do not use Redhat, so if questions, direct it to their mailing lists ...

Sahara Workshop <[email protected]>



-  PLEASE NOTE -

This email and any files transmitted with it are confidential and
intended solely for the use of the individual or entity to whom they
are addressed. If you have received this email in error please notify
the system manager. Please note that any views or opinions presented
in this email are solely those of the author and do not necessarily
represent those of Sahara Distribution (Pty) Ltd. Finally, while Sahara
Distribution attempts to ensure that all email is virus-free, Sahara
Distribution accepts no liability for any damage caused by any virus
transmitted by this email.

Sahara Distribution (PTY) Ltd
Unit G5-G12, Centurion Business Park, Milnerton, Cape Town, South Africa
Private Bag X180, Halfway House, 1685, South Africa

Scanned and protected by Sistech Viruswall 2.3