Zenmap intense scan crashes network

Dogs · 05-13-2010, 04:24 PM

I just started messing with the networking tools in Linux, and I've discovered that when I run an intense scan in zenmap on 192.168.1.1-254, the network crashes.

By network crash I mean - All clients on the network lose connectivity.

I was hoping someone could explain the intricacies behind this phenomenon.

zenmap v5.00
Linksys 54G wireless router.

kbp · 05-13-2010, 08:40 PM

Sounds like a bug in your router, see if you can locate some newer firmware for it

cheers

brucehinrichs · 05-13-2010, 10:44 PM

If you do decide to flash it, consider dd-wrt. I've flashed 3 linksys WRT54Gxx routers with their firmware. IMHO, much better firmware than linksys.

EDIT: Check the full model number against their handy router database.

Dogs · 05-13-2010, 11:08 PM

Whoa. I didn't realize it would be such a quick thing to do flash the firmware. Thank you for that info.

I haven't ever upgraded the firmware since I got it in the early 2000s, so I have a pretty good feeling about that solution.

How can I search for the bug, though?

kbp · 05-14-2010, 12:37 AM

Don't bother.. sometimes these sorts of things are fixed quietly. If there's newer firmware, upgrade...

cheers

brucehinrichs · 05-14-2010, 12:49 AM

Dogs, if you do flash it with the dd-wrt firmware, post back and let me know what you think.

Dogs · 05-14-2010, 05:42 PM

Quote:

Originally Posted by brucehinrichs

Dogs, if you do flash it with the dd-wrt firmware, post back and let me know what you think.

Will do. Net needs to stay on until Sunday, though, so it will be a couple of days. I'm also looking at OpenWRT.

LVsFINEST · 05-14-2010, 08:10 PM

Running Nmap opens ALOT of connections. Each connection has to be "tracked" so to speak. Most consumer grade routers track connections looong after they're not needed (thus taking up unnecessary "space" in the connection table), plus most of them only have 16MB of ram which isn't a whole lot at all. In other words, your router's connection table is probably exceeding it's limit, then dies. And most router manufacturers don't allow you to tweak these settings, although I do believe dd-wrt does. Theoretically, you could run into the same issue even after upgrading the firmware.

brucehinrichs · 05-14-2010, 08:55 PM

Dd-wrt offers a wide array of tweaks and fine-tunings. I was amazed at what my $50 router could do after flashing it. I'm curious to hear Dogs' (and any others) opinions without overstating my own beforehand.

brucehinrichs · 05-15-2010, 11:05 PM

Here's a modded WRT54G.

Dogs · 05-15-2010, 11:40 PM

Quote:

Originally Posted by brucehinrichs

Here's a modded WRT54G.

I think I found a cool project for the summer.

Quote:

Chances are though, if you’re confident in performing these upgrades, you couldn’t give a darn about warranties. You’ve already voided more of them than you care to keep track of. AmIright?

I have, yes.

Quote:

The $50 WRT54G with DD-WRT firmware in a parabolic dish setup helped to set the 2nd place world record for unamplified Wi-Fi distance in Venezuela @ 173miles!!!!

That seems a bit unbelievable, but in the event it is true I must have it, because ---

Quote:

With this one I’ll be using it for an ad-supported neighborhood Wi-Fi which provides both an internet source for people who cannot afford it, but also a way to reduce costs for the person who pays for the source connection- usually high speed cable service that a single household will never fully utilize

that's what I want to do, too =)

Joe of Loath · 05-16-2010, 11:19 AM

Quote:

Originally Posted by Dogs

That seems a bit unbelievable, but in the event it is true I must have it, because ---

I can't believe it could manage to go round the curvature of the earth... I've had almost 7 miles without any special antennae though, simply through having line of sight.

Dogs · 05-23-2010, 01:56 AM

Replacing my ancient firmware with DD-WRT fixed the problem.