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Degrade Your Own Network
cryptonix writes: "This device seems pretty cool. it attaches to your network and allows you to degrade network preformance (for testing purposes only of course). runs on windows and supports gigabit ethernet or 10/100 networks. There's more info at emprix's site about the PacketSphere." Alright, that's funny as hell, and frankly a really good idea.
I don't know how to put this, but you're an idiot. Seriously.
Network tools have existed for *decades* that introduce error in networks. What are they used for?
Well, let's say you're developing software that handles _anything_ on a network. Sure would be nice to know how it behaves when packets are dropped, delayed etc. Or let's say you're closer to the wire and want to know how the router chip you're programming behaves under simulated load.
But, if you're just a CONSUMER of technology, and don't actually use it for anything useful beyond your own entertainment, then perhaps you have a point; such a device is not useful and should be left to the professionals .
:)
hawk
It sounds like this device does exactly what the Dummynet feature in FreeBSD (and others, possibly?) does. I've been throttling back NNTP grabs by Leafnode, big downloads, and so on for a while now, to keep my WAN connection from being flooded.
Of course, it doesn't exactly run on Windows...
--- Chris
Just download Sniffit and "Touch of Death" from HERE
Will autokill any connection you see ;-)2 C3AF4F2snlbxq'|dc
--
echo '[q]sa[ln0=aln80~Psnlbx]16isb15CB32EF3AF9C0E5D727
echo '[q]sa[ln0=aln80~Psnlbx]16isb572CCB9AE9DB03273snlbxq' |dc
Well, not as complete and not as a transparent etherenet level device. We don't do reordering
:-)
or packet multiplication and the linux box functions as a router.
The relevant piece you want to use is the `packet scheduler'. There are a variety of scheduling algorithms in there. You might use a command like...
tc qdisc add dev eth0 root tbf rate 1500Kbit buffer 15Kb/8 limit 100Kb
tc qdisc add dev eth1 root tbf rate 1500Kbit buffer 15Kb/8 limit 100Kb
... to throttle your network to T1 speeds. Note that you have to do both interfaces as the scheduler works on outgoing packets only.
I used to have a custom scheduler module that was a packet loser. It turns out to be a bad idea for tcp analysis. (Consider, most of the overloaded routers we meet are running some sort of fair queueing. They are deliberately causing loss to achieve a rate limitation. When you observe packet loss, it is not the loss that causes the limitation, it is the limitation causing the loss.)
For the industrious, as of linux 2.4 I believe a packet loser is much better to implement as a firewall module. Its on my `someday when I have time' list. I also plan a latency module. Nothing like latency to expose chatty network protocols. (cough sqlnet cough, "it worked fine in the development building, I don't know why your global users are complaining"
Agreed, you are dumb! Read the damn article, the device doesn't degrade network by flooding, instead, it does so by perhaps making you lose every nth packet, causing duplicate packets, adding time delays, etc. Did you even freaking read the article? This is a must have for anyone who is running a real network. Try this in a real network with firewall and IDS deployed, they will not notice, no logs or alarms setting off, real life simulation. Sheesh, some people are dumb, people like you.
------ Curiosity killed the cat. {satisfaction brought it back | it didn't die ignorant | lack of it is killing mankind
No comment. ... What's a stack?
------
I'm an assembly guru
Nemesis allows for all types of injection meaning you create the packet(s) you want to send. So if you start with sequence 1927364 .. 19*365 then 19*400 it still accomplishes the same thing for one.
Secondly many firewalls would filter most of the garbage that program would send whereas using Nemesis along with Fragrouter would allow you to cimrcumvent both IDS, and Firewall as well
Again its still free so STFU clown
Want Root?
Having worked on some big LAN/WAN implementations in the past I can say I'd have liked to have this device. The features allow you to emulate "what'd happen if..." - always nice when you're setting up a few hundred workstations on a WAN and some Induhvidual says that a 1Mb dedicated line is sufficient : )
- A picture should be mandatory, especially after that intro text ("tech editors were already exchanging a flurry of e-mail messages about how cool the device looks")
- Price. Sorry, can't seem to find one. Urgh.
Oh, and I must say I don't understand the tech editors at Network Computing much, since I found the box' appearance rather uninspiring. I would very much like to have one at work, though. Debugging flow-control code on localhost is too easy.main(O){10<putchar(4^--O?77-(15&5128 >>4*O):10)&&main(2+O);}
Wouldn't an AOL subscription be alot cheaper?
Someone you trust is one of us.
So for applications that send large amounts of data, without much cpu overhead and harddrive io overhead, this gizmo is great -- but not for those situations where network load is also accompanied by high cpu load as well as many harddrive accesses. In fact, I'd go so far as to say that this thing is completely useless for almost all but the most bandwidth hungry network applications.
for starters, you can test how your business applications will run in a stressed environment. It may be hard to imagine, but a lot of software (custom code especially) works a bit differently under stressful conditions. Think about applications that have dependencies on data from other applications...how do they react when such data takes a bit longer to arrive? btw, this is only one example out of many ;]
"My mother never saw the irony in calling me a son-of-a-bitch." - Jack Nicholson
seeing how things, eg. network filesystems, react to heavy traffic, errors and whatever weirdness real networks might face.
this is the kind of tool (stress tester) more developers and beta testers need to use, in order to find bugs BEFORE it gets loose in the real world where these kinds of things normally happen.
runs on windows
IS Windows...
I'm looking for such a tool because I'd like to be able to assess the speeds of doing certain things over a modem link (such as browsing a web site I've designed, or running a particular X application) usinga LAN, as opposed to the bother of actually using a modem. I've considered hacking rinetd around to do it, but no sense reinventing the wheel...
Fragmentation, packet replay, spoof attacks, firewall/vpn interoperability to name a few.
era-era-boom shakalaka.
Mixmaster Mike on the network! Raise the Latency!
On a more serious note, what happens if you connect several in sequence? Is it like dueling banjos? What about 4? A barbershop quartet?
Maybe it's just laggy.
<p>Isn't network automatically downgrade when a Windows box is plugged to it? No?</P>
<P>My office has three NT servers spewing useless netbios packats day and night, while the Linux server is so busy to ignore them...</P>
a http proxy server like squid has "delay pools" that will limit bandwidth. So for your testing you could login as modem/slow or something and get a speed of a modem user.
I can work for years by hiding that gizmo somewhere at work, fixing the problem then repeating somewhere else in the building.
Woohoo!
The slashdot effect will teach them what network degradation really means. ;-)
kryps
If you were a true BOFH, what better way to upgrade your servers than by showing your beancounters the small "deficiencies" of your current network?
Linux *is* user friendly. It's not idiot-friendly or fool-friendly!
Looks like all of the BOFH's across the world will be running out to buy this baby! :)