[I had to repost this from the ask.wireshark.org as my questions do not come up there, still not sure why].
Hi All,
I'll try my luck here.
I'm trying to solve a similar problem to the one described in "how to work around unicast messages" question, albeit in my case I'm not seeing an ARP reply (unicast) in Wireshark.
I need to say that I have read everything that was suggested in that thread (wireshark help and a set of other documents on Ethernet Capturing/Hubs vs Switches vs Taps, etc.) and still puzzled, so basically would love to hear any ideas thrown at me by experts.
So:
it is Ethernet;
3 devices:
1. a custom device (running embedded linux)
2. a PC (WinXP) where wireshark is running (promiscuous mode, capture all)
3. a PC where a server application is running to which the custom device communicates.
all 3 connected to [what is believed to be] a simple hub "CentreCom MR415T repeater" 10BASE-T only (not dual speed).
I'm seeing all the traffic I expect to see in Wireshark but NO ARP replies (unless they are sent to the Wireshark PC).
For the problem I'm trying to nail it is crucial to tell whether there are NO replies to ARP requests sent by custom device (1) or it (the device) is unable to correctly handle these replies (which is quite possible).
All other symptoms point to the latter but I need to actually SEE and be able to SHOW this as a proof.
Thanks in advance to anyone who replies,
Alexei
UPD. 2016/06/09: In advanced settings of Panda Firewall found a tick box "SmartARP" - unticked and this solved the issue.
The ultimate reason of not seeing ARP replies in Wireshark turned out to be: Panda End Point Protection Plus Firewall. Not the most flexible piece of software as far as I can see, creating a User rule for Wireshark to allow both incoming/outcoming does not help in the slightest, but disabling the firewall - does.
Related
I need to slow down (simulate bad) internet connection, I found some documentation where it was achieved by "ipfw pipe" command , the thing is that in latest MAC OS versions , ipfw was deprecated (and removed)...
I was wondering if there are any alternative to the ipfw API ?
Does anyone know how latest Network Link Conditioner achieves it?
The original previous way which enabled to slow down an internet connection :
sudo ipfw pipe 1 config bw 56Kbit/s delay 200 plr 0.2
and to clear the pipe :
sudo ipfw delete 1
Thanks.
I don't know much about Mac OS (I use Linux myself), but I'll give this a shot.
A bunch of digging established that ipfw seems unavailable, as you say.
I was also unable to find a way to use the Network Link Conditioner from the command line. Everything should be usable from the command line, so that's stupid.
One work around would be to try to access the NLC from within AppleScript. The following will get you started on toggling the NLC:
property thePane : "com.apple.Network-Link-Conditioner"
tell application "System Preferences"
activate
set the current pane to pane id thePane
--delay 2
end tell
---
tell application "System Events"
tell application process "System Preferences"
try
click ((checkboxes of window "Network Link Conditioner") whose description is "enable switch")
on error
click ((checkboxes of window "Network Link Conditioner") whose description is "enable switch")
end try
end tell
end tell
I think that you can run a script from the terminal with osascript <SCRIPT>.
As an alternative, Charles Proxy is a pay-to-use program that can be used to perform throttling, provided you can convince the software you are testing to connect to the proxy's port rather than directly to the internet. Maybe there are free proxy solutions out there somewhere?
Perhaps Squid would work in that regard. SquidMan seems to be an easy-ish way to install it for Mac. It looks as though DelayPools and or Client Bandwidth Limits might be useful for simulating a low speed connection, though I can't find evidence of people having used them for such.
I found several solutions that might work. They come from some old threads, but they might help:
How to simulate slow internet connections on the mac
Apple has made a very handy official tool to slow down the network connections on you Mac for testing purposes.
The Network Link Conditioner preference is a free download from within Xcode (for Lion and later OS). Additionally, iOS has similar function accessible from within Xcode and iOS 6 or later.
How do I simulate a bad Wi-Fi connection on my iPad?
There are a few ways you can do this, depending on your situation:
Move further away from your router. While this may seem a bit obvious, I realize that it isn't always possible while testing/debugging (for example, if you are working on a desktop computer).
Put aluminum foil around the router and/or antenna. This will (partially) block some or all of the radio signals by creating a makeshift Faraday cage. The results you get will depend on the strength of your router signal, distance from the router, and other environmental factors.
Set your router's wireless signal power to a lower setting. The method for doing this is different for each router, so you will have to look at the user guide for instructions on how to do this.
Slow down internet for iOS simulator
You can set the network to slow characteristic by testing on devices. Go to Settings -> Developer Settings -> Network Link Conditioner -> Enable. This is for iPhone/iPad running iOS 6
I don't know if the last one you can still do.
I've used many methods in the past for slowing down network connections, among them:
performing a parallel download of some massive Linux ISO file;
physically pulling out the Ethernet cable (at one point, I actually toyed with the idea of building a push-button device that would sit between two cat5 cables and do this without having to physically disconnect the whole cable).
using ifconfig eth0 down ; sleep 1 ; ifconfig eth0 up.
Hopefully one or more of those methods will help.
If you're looking to slow down your network connection because you're doing testing/profiling work, one option is to get a specific device that can create network latency/noise.
For example Apposite Tech's mini2 WAN emulator allows you to change values for bandwidth and packet loss. You can roll your own device too using something like: http://wanem.sourceforge.net/ . It just depends on your needs, time and budget.
I am trying to connect ICP CON i-7565 (USB<->CAN interface) to a custom made device (supporting CAN2.0B, proved to work with PCL-841 card) Although I think I have configured BAUD and acceptance code/mask correctly I can see CAN no messages coming from the device (ICP provides a tool that should allow me to send and receive CAN messages).
I am new to CAN bus so I appreciate any help regarding how to identify the problem.
I-7565 might be wrong interface for me, I might have misconfigured it, or it is simply broken. Or I am just doing something wrong out of my ignorance. I don't think anyone can help me with my specific problem, so I am rather asking for general information on how are problems with CAN bus identified and analyzed. In TCP/IP for example, you would call ping, you'd recheck your ip and gateway settings etc. What do you do for CAN communication?
Additional info:
OS: Win7 64bit
connector: DB-9 with standard wiring (2,3,7)
Finally I tried to work with different USB<->CAN interface from different manufacturer and it worked like a charm. My old interface was either broken or incompatible for reasons unknown. While working on this problem I learned couple of things about CAN bus and so now I share what I think was the right answer to my original question: How to troubleshoot CAN bus communication?
read manual to your USB-CAN interface
install driver of your interface device and make sure it is working (check device manager, depending on the type of your device you will see new COM port added or new USB controller )
your device should be shipped with it's own test/analysis software (they might call it utility or similar), run it and check if it can connect to your device
CAN communication uses three wires that are referred to as High, Low and Ground and is usually connected with DB-9 connectors where High is linked to pin n. 7, Low to pin n. 2 and Ground to pin n. 3 or 5 - make sure this is connected correctly on both your USB interface and CAN device you want to communicate with
set properties of your connection, these are most of all: CAN type (2.0A or 2.0B) BAUD rate, Acceptance Code and Acceptance Mask
if you've done all of this and still you can see no CAN messages arriving in your utility program, check with a different USB-CAN interface or find some other way to test if your device is actually emitting CAN messages and your USB interface is in fact able to receive them. (this was actually my case)
I'm trying to get a very old, but working great C2001A/J4100A (HP LaserJet 4) to work with the HP Linux Imaging and Printing library, but I'm having an awful time of it.
1) There's no entry in /usr/share/hplip/data/models/models.dat for [hp_laserjet_4]. This is the first problem so far when I used Bonjour discovery through an avahi.service file I put on my OpenWRT router. I don't currently have an iPhone I want it to discover with AirPrint, but this is how I started off and helps CUPS finds printers anyways.
2) SLP discovery is a complete bomb. I've traced it down to the UDP packet the JetDirect sends off in response to the broadcast discovery request. The part that is 'x-hp-p1=0' should be something like 'x-hp-p1=MFG:HP;MDL:LaserJet4;etc..' and it causes hp-probe to fail to see what printer the JetDirect is plugged into.
I can't seem to force HPLIP to bypass the bad discovery methods and it's too smart and wants to verify.
I've posted to the HPLIP help area, but they seem to run a week slow.
Instead of doing JetDirect, try LPR directly to the IP address. And any of the older PCL drivers should work against that printer.
What would be the best way of sending a signal from an iPad to an Arduino?
I am trying to use XBee, with iPad and Arduino to send a wireless signal.
I want to make a big red virtual button on an iPad that, when pressed, turns on an LED on the Arduino.
I am a total newbie when it comes to iOS, but OK with Arduino and XBee.
So I'm not sure if I understood correctly, but in my meaning there is only one simple way to solve the problem:
Connect an XBee to a Computer and another to the Arduino. On the computer you launch a webserver, which will be accesible from the iPad over Safari. This server handles the clickes and writes to the XBee Com Port, for communication.
Here are some examples, people already made:
http://www.projectallusion.com/1/post/2009/11/iphone-controlled-solar-powered-arduino-tank.html
http://www.sparkfun.com/tutorials/152 (not with xbee, but you can implement that by yourself)
I know it's been a while but I just came across to this question and yesterday I was doing the exact same thing so I'll share the method I used and the source of it.
In order to set a LED on or off in an Arduino board from the iPad you really don't need anything more than a browser. This is of course if you have a way to connect that Arduino to the local network.
Today you have at least two options. The WiFi and the Ethernet shields. Once you have your Arduino board inside the network you can send the instructions (HIGH or LOW) to the board form the browser.
These are my two boards connected waiting to be plugged to the local network:
Of course, you'll have to code the board to process those instructions. There are many examples on how to configure network settings and state instructions:
If you have a bit of time and want to do something more elaborated you could create a simple app to graphically control the state of those LED(s).
Inside you'll basically do the same thing, create the URL command and send it to the Arduino IP but it'd look much nicer. If you integrate later more controls the sky in the limit.
My experiment is a combination of what I learned from this nice tutorial and some tips I've read here and there.
I hope it becomes also useful to someone else.
Cheers,
Since you need to use a network connection from the iPad, a possibly simpler way to do this would be to use a WiFi module on the Arduino to poll a web script, and have the iPad write a state (button press) to that web script.
There's a handy WiFi module called the RN-XV that's designed like an XBee. I wrote up two tutorials on it:
http://log.liminastudio.com/programming/getting-started-with-the-rn-xv-wifi-module-node-js
http://log.liminastudio.com/itp/physical-computing/using-the-rn-xv-wifi-module-as-a-remote-switch
I've just installed pfSense (a FreeBSD distro) and I'm having problems with my Ethernet adapters - I seem to be able to get it into a state where I cannot ping any machine despite the ARP tables etc... all being correct (On the machine I'm pinging I can see the packets arrive and the response sent in Wireshark, but the remote machine gets nothing)
Having an interest and limited knowedge in OS development I kind of want to have a go at debugging this, but in many ways I'm not really sure where to start:
How do I go about getting the source code for the drivers I'm using? Will they be part of the FreeBSD source code, or is there going to be some external project? (or are the drivers I'm using likely to be the proprietry ones released by Realtek, and therefor not have source code)
For that matter, how do I identify what drivers I'm currently using?
Finally, are there any good resources on how to debug Kernel-level / device drivers?
(I appologise if I'm asking silly questions or if I seem overly optimistic about what I'm hoping to achieve by debugging this, but although I lack experience in this area I consider myself to be a smart guy and I've gotta start somewhere!)
I really doubt your problem is in the device drivers or other kernel code. Check the PF rules - you most probably just dropping all ICMP packets out right.