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Questions[overflow](server)

Martin Hope
Justin Sybrandt
Asked: 2012-02-16 15:48:21 +0800 CST
  • 2

I work for a Conference Center and we are rebuilding the network for our guests to use. I am functionally a high school intern with relatively little networking experience but I have so far put in a new router to replace our old one and put new AP's around the building. All the equipment is /24 or Class C (not by choice) and my new concern is that we will have far more than 256 guest devices on this router.

So I have been looking into VLAN thinking that maybe I can branch off half the devices into a different subnet so that I could have 512 devices between 192.168.1.* and 192.168.2.* I am using a Cisco 4 port Gigabit RVS4000 and so far it seems I can't do that (hopefully I'm wrong).

So then I thought maybe I could reconnect the old, still perfectly functional router as a redundant system on 192.168.2.1 and set that DHCP to grap the X.X.2.* range, but I'm concerned that would either mess up our seamless roaming or not connect properly to the AP's that are still on X.X.1.(2-6) (although I would like to be paid to come in and change their IP's every time we needed to use the overflow system I don't think my boss would appreciate the extra work).

I also think there should be a better way than two whole routers.

So is there anything I'm missing or should I just keep plugging about with parallel routers?

EDIT: Router only supports 255.255.255.* which is horrid http://i.imgur.com/icXBd.png

networking vlan cisco overflow
Martin Hope
Darren
Asked: 2010-11-30 19:43:49 +0800 CST
  • 1

We have had PCI compliance for about 4 months straight then all of a sudden this comes up:

Fail
Serious
Port: 21 
Protocol: tcp
Summary : attempts some buffer overflows
CVSS Base Score : 10.0 (CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C) 
CVSS Temporal Score : 8.3 (CVSS2#E:F/RL:OF/RC:C) 
Public Exploit Available : true
CVE : CVE-1999-0219, CVE-2000-0870, CVE-2000-0943, CVE-2000-1035, CVE-2000-1194, 
CVE-2002-0126, CVE-2003-0271, CVE-2005-0634, CVE-2005-1415 
BID : 269, 1227, 1675, 1690, 1858, 3884, 7251, 7278, 7307, 12704, 13454

The server has cPHulk Brute Force Protection on and FTP users are required to use SFTP. I do not understand how I can secure this anymore than I have... I do not want to change my Brute Force Protection settings because it currently just drops the user and doesn't give them any message, and I am afraid that is what is happening. The audit company is Trust Guard; does anyone have any suggestions or has anyone had a similar experience?

security pci-dss overflow
Martin Hope
Martin
Asked: 2010-01-21 03:19:09 +0800 CST
  • 0

I have got the following question from a course:

"Assume a TCP connection over the internet with a useable bandwith of 300Mbps. Assume that some packets are transported with a very high delay. At which delay time serious problems may occure? Is this a realistic problem?"

I calculated that at a delay time of ~2 minutes, there will be an overflow within the sequence counter (if you assumed that it started with 0). According to RFC the sequence counter will overflow to zero. I found no "what to to if this happens" within the RFC, but maybe i overlooked it.

My question is: What will happen? Is this simply a limitation of TCP? Are there workarounds (except of using a larger sequence counter)?

tcp overflow