nanog mailing list archives

Re: Cisco says attacks are due to operational practices


From: Bora Akyol <akyol () pluris com>
Date: Fri, 11 Feb 2000 10:58:08 -0800


Unfortunately, ssh on linux regularly assigns ports when ssh'ing out from a box
below 1024, I think this is a bug, but make writing firewall commands annoying.

Bora


"John M. Brown" wrote:

Umm, lets see, hosts are supposed to assign ports for sessions above 1024.
Ports below 1024 are "priv / root" ports and are assigned for specific
services.

We filter <1023  >1023 we don't care about so much, except for a couple of
well known ones.

On Thu, Feb 10, 2000 at 07:02:25PM -0800, Chris Cappuccio wrote:

Did anyone even read the post I was responding to ??

On Thu, 10 Feb 2000, John M. Brown wrote:
| We have always built martian filters on our edge routers.  In addition we
| built specific filters for ports that are not used, or are bad on the net.

"Ports that are not used" What about when the tcp stack on a particular
machine dynamically allocates a particular port for some tcp connection and
you are filtering that port ? etc....



On Thu, 10 Feb 2000, Paul Ferguson wrote:

 | I did't see anyone talking about port-level filtering. What
 | I did see, on the other hand, was someone talking about about
 | filtering Martian network traffic -- stuff which should not
 | be there in the first place.
 |
 | - paul
 |
 |
 |

---
Gates' Law: Every 18 months, the speed of software halves.






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