I tried with sudo ethtool -G eth0 rx 1020, but im getting this error Cannot get device ring settings: Operation not supported. Is there any other way to change network buffer to simulate NIC card errors and Packet drops. Thanks
Netem can simulate all kinds of packet delay, corruption etc.http://www.linuxfoundation.org/collaborate/workgroups/networking/netem
Related
I'm trying to send UDP packets over the t-mobile NB-IoT network using AT-commands on a SIM7020E chip. I used the product wiki as reference. The starter version of the sim card I have doesn't support TCP, but I'm planning on using that later if I can succesfully communicate using UDP.
I created a UDP-socket on a Raspberry Pi using "nc -u -l 9999". I set an A-record on my hosting provider to refer dev.mydomain.com to the IP address of the Raspberry Pi. I verified the portforward and A-record settings by sending UDP packets from my laptop on another network using "nc -u dev.mydomain.com 9999" and typing some teststrings, so this all works.
On the 4G chip I use the following AT-commands:
// Check network
AT+CSQ
+CSQ: 21,0
AT+CGREG?
+CGREG: 0,5
AT+COPS?
+COPS: 0,2,"20416",9
AT+CGCONTRDP
+CGCONTRDP: 1,5,"iot.t-mobile.nl","x.x.x.x.255.255.255.0" <-- crossed out my ip
// Create UDP socket
AT+CSOC=1,2,1
+CSOC: 0
// Connect socket 0 to the listening port on the Raspberry Pi
AT+CSOCON=0,9999,"dev.mydomain.com"
OK
// Send "test"
AT+CSOSEND=0,0,"test"
At this point I expect to see "test" appear in the command line on the Raspberry Pi, but nothing happens. In the T-mobile portal it shows a PDP-context is successfully activated.
Also, setting the APN manually with AT*MCGDEFCONT="IP","iot.t-mobile.nl","username","password" doesn't work.
Did you work this out Hans? I was plodding along with a SIM7020E following https://www.waveshare.com/wiki/Pico-SIM7020E-NB-IoT code examples. Was successfully sending HTTP GETS to a server (without having to use micropython's wretched urequests lib) via the CHTTPCREATE/CHTTPCON/CHTTPSEND AT cmds, that seem to be be able to send packets over LTE to a server without specifying TCP/UDP etc or using a socket. Maybe give it a try?
Sadly I got the bright idea of trying an 'AT+POWD=1' cmd over the uart (was supposed to power the 7020E down) & now the module now does nothing but echo AT cmds (still auto connects to the LTE network & slow flashes the network led, just won't do anything else.) Real shame, nice little module otherwise.
How is it possible to authenticate using Bluez 5.31 and GattTool?
I want to listen on a notification.
I've connected using gatttool -b <addr> -I and I can run the primary command etc.
I sniffed the device and I know that handle 0x0024 is where I will find a notification.
When I try char-write-req 0x0024 0100 I get Error: Characteristic write Request failed: Attribute requires authentication before read/write
So I try sec-level medium and then sec-level high but I still get the same error.
Any ideas?
I'm developing an embedded device which has access to the internet through LAN.
I'm in the testing phase now, and I would like to test how the device performs when the connection to the internet is poor.
Currently, the device is connected to a router through a hub, which I use to monitor the packets with Wireshark.
What's the best way to throttle down the internet speed of the device to mimic a scenario that may happen?
Can I do it through a PC? Do I need access to the router? If so, is it possible to limit the speed of each IP in the router interface?
Actually, a friend suggested that I will purchase a usb2lan ethernet card, and to bridge the PC lan connection to the embedded device, and then using a software QoS limiter. do you think it will work ?
If you have a Mac handy, Macs have kernel facility called dummynet built in, which you control through ipfw. It allows you to simulate a slow connection, randomly drop packets with certain probabilities, and more.
The same facility exists in Linux and other OSes.
From the dummynet homepage:
As of Feb.2010 we have released the third major version of dummynet,
which now runs on all main platforms: FreeBSD, Mac OS X as part of the
native distributions, and you can find Linux, OpenWRT and Windows
versions here.
It can do a lot for you:
limit the total incoming TCP traffic to 2Mbit/s, and UDP to 300Kbit/s
ipfw add pipe 2 in proto tcp
ipfw add pipe 3 in proto udp
ipfw pipe 2 config bw 2Mbit/s
ipfw pipe 3 config bw 300Kbit/s
limit incoming traffic to 300Kbit/s for each host on network 10.1.2.0/24.
ipfw add pipe 4 src-ip 10.1.2.0/24 in
ipfw pipe 4 config bw 300Kbit/s queue 20 mask dst-ip 0x000000ff
simulate an ADSL link to the moon:
ipfw add pipe 3 out
ipfw add pipe 4 in
ipfw pipe 3 config bw 128Kbit/s queue 10 delay 1000ms
ipfw pipe 4 config bw 640Kbit/s queue 30 delay 1000ms
You can try using "Fiddler"
You have options to simulate bad network (like old modems 33k or 56k)
You need to plug in your device to your PC and turn on the proxy (every request will be transfered through Fiddler)
Then you could test your code with a bad network then see what happening ;)
You may use (almost) any linux distribution from liveCd (like ubuntu, mandriva, others) to run it on any hardware you want, and use the kernel-based tool netem, aka "Network Emulation" with the "iproute2" package tools. It lets you control delays, package loss, corruption, duplication and other possible problems of wide area network.
There is list of most used simulations, like:
Rate control using Token Bucket Filter:
tc qdisc add dev eth0 root handle 1:0 netem delay 100ms
tc qdisc add dev eth0 parent 1:1 handle 10: tbf rate 256kbit buffer 1600 limit 3000
Delay all packets by fixed time: tc qdisc add dev eth0 root netem delay 100ms
Package loss: tc qdisc change dev eth0 root netem loss 0.1%
This is another OSX solution, have a look at the Network Link Conditioner.
The following quote is ripped from the following blog (All credit for the below should go to Matt Gemmell):
http://mattgemmell.com/2011/07/25/network-link-conditioner-in-lion/
Get the Hardware IO Tools for Xcode. To do this, go into the Xcode
menu, then choose “Open Developer Tool” and finally “More Developer
Tools…”. You’ll be taken to Apple’s developer downloads site; you
should download the “Hardware IO Tools for Xcode”.
The resulting disk image will contain (amongst other things) a
preference pane for System Preferences, called “Network Link
Conditioner”. Double-click the prefpane file and authenticate to allow
it to be installed. You’ll then see the pane in System Preferences.
You can choose from various different types of network conditions
using the Profile popup menu.
You can also add profiles of your own by clicking Manage Profiles,
either from scratch or via duplicating an existing profile.
Extremely handy for simulating less than optimal network conditions
while testing an app. Just don’t forget to switch it off afterwards!
I have an application that does a lot of binary data loading. I've encountered scenarios where an unstable 3G connection may intermittently cut out during the loading of some of this binary data, causing issues.
Is there any way, using the simulator or otherwise, to test for low-bandwidth/unstable connection scenarios?
I seem to recall Adobe Flash having bandwidth simulators in their test suite.
You can accomplish this by creating a wireless network on your Mac using Internet Sharing, degrading that interface using firewall rules, and connecting your iPhone to that network. This will actually work to debug any device that connects to a wireless network.
Using this technique, you can simulate extremely meager, lossy, or latent networks.
I use this technique instead of Apple's official Network Link Conditioner for a couple reasons:
Throttling can be applied only to specific connected devices, rather than affecting your development machine's network connection.
It can be scripted to simulate rapidly changing or "bursty" networks.
Unlike the Network Link Conditioner built into iOS, you can change the settings while your application remains in the foreground.
This uses ipfw's dummeynet feature. ipfw is technically deprecated in modern versions of OS X, but it still works fine. Unfortunately, pf (the replacement) doesn't yet support arbitrary packet delays. I'll update this answer if something changes.
Creating an awful Wi-Fi network
Plug into Ethernet if you aren't already.
Enable Internet Sharing in the Sharing pane of System Preferences. Choose to "Share your connection from: Ethernet" and check "Wi-Fi".
Get your phone connected to the network you just created and make sure you can browse the web.
Tell Mac OS's built-in firewall (ipfw) to ensure packets that have latency applied (pass through the "dummynet" in ipfw parlance) are still routed through the normal rules. This allows Internet Sharing to continue working:
phil#Nebula ~$ sudo sysctl -w net.inet.ip.fw.one_pass=0
net.inet.ip.fw.one_pass: 0 -> 0
Configure the low-quality pipe through which your iPhone's traffic will pass (14Kb/s throughput with 1% packet loss):
phil#Nebula ~$ sudo ipfw pipe 1 config bw 14KB/s
phil#Nebula ~$ sudo ipfw pipe 1 config plr 0.01
The next step varies depending on whether you're on Mountain Lion or below, or Mavericks.
For Mountain Lion (10.8) or below:
Route packets into the pipe, but only for traffic over your AirPort interface:
phil#Nebula ~$ sudo ipfw add 10 pipe 1 ip from any to any via en1
00010 pipe 1 ip from any to any via en1
Important: If you're using an Air or new MacBook Pro without a physical ethernet port, your AirPort interface will likely be called en0. Replace en1 with en0 above if that's the case.
For Mavericks (10.9):
Check the output of ifconfig and look for the bridge interface created by Internet Sharing:
bridge0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=63<RXCSUM,TXCSUM,TSO4,TSO6>
ether xx:xx:xx:xx:xx:xx
Configuration:
id 0:0:0:0:0:0 priority 0 hellotime 0 fwddelay 0
maxage 0 holdcnt 0 proto stp maxaddr 100 timeout 1200
root id 0:0:0:0:0:0 priority 0 ifcost 0 port 0
ipfilter disabled flags 0x2
member: en4 flags=3<LEARNING,DISCOVER>
ifmaxaddr 0 port 6 priority 0 path cost 0
nd6 options=1<PERFORMNUD>
media: <unknown type>
status: inactive
bridge100: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=3<RXCSUM,TXCSUM>
ether xx:xx:xx:xx:xx:xx
inet 192.168.2.1 netmask 0xffffff00 broadcast 192.168.2.255
Configuration:
id 0:0:0:0:0:0 priority 0 hellotime 0 fwddelay 0
maxage 0 holdcnt 0 proto stp maxaddr 100 timeout 1200
root id 0:0:0:0:0:0 priority 0 ifcost 0 port 0
ipfilter disabled flags 0x2
member: en1 flags=3<LEARNING,DISCOVER>
ifmaxaddr 0 port 5 priority 0 path cost 0
media: autoselect
status: active
You want the bridge interface that has an IP address; in most cases, it will be bridge100.
Route packets into the pipe, but only for traffic over the bridge interface:
phil#Nebula ~$ sudo ipfw add 10 pipe 1 ip from any to any via bridge100
00010 pipe 1 ip from any to any via bridge100
Change bridge100 if it has a different name on your system.
Simulating a changing network
You can change the values 14KB/s and 0.01 in step 5 above to simulate different types of networks. You can also specify config delay 1000 to introduce a 1000ms delay. See the manpage for more options.
You can continue to reconfigure the pipe after adding the rule for it. For instance, to simulate nearing the edge of cellular coverage, issue this command while your app is running and connected (95% packet loss):
phil#Nebula ~$ sudo ipfw pipe 1 config plr 0.95
There is no need to run sudo ipfw add 10 … again after reconfiguring the pipe. You can script these changes to simulate an extremely dynamic network environment.
Cleaning up
You can issue sudo ipfw delete 10 to put everything back to normal, or just reboot.
Here is a great script I've used on OS X to throttle connection speed, or just turn it off, for any domain you want. I wish I could remember where I got it from to give credit.
Save the code to a file on your machine and name it "throttling". Then to run, just enter the below in terminal, and select from one of these speeds: [full|fast|medium|slow|wwdc|off].
"./throttling medium"
If you have the script set up to throttle localhost:3000 and stackoverflow.com, then loading up a page from either of those domains in your browser (or iphone simulator or whatever) will respond slower and load files slower. It's been really great for testing iphone connectivity bugs.
http://gist.github.com/499177
You could test a number of things if you turn 3G off and connect to wifi.
Log into your router and rate limit the mac address of your iphone. (to test slow connections)
Kill the power to the wifi when in the middle of downloading data
Reboot the wifi router when downloading so the phone has connection, loses it, and gets it again. ( to test different scenarios )
Happy Coding!
I read of someone testing with their iPhone connected by USB cable and the phone wrapped in aluminum foil to get the cellular signal reduced. You can turn off WiFi and 3G and just have Edge and then attenuate it with foil. Sounds crude but...
You could also use an iPhone 4 and hold in your hand to short the two antennas together ;-)
Chrome 38 includes network emulation in the device emulation settings. You can select from Offline, GPRS, EDGE, 3G, DSL and WiFi. Also emulates increased latency.
It's not as accurate as testing on a real device but it's much quicker to set up.
Well, low bandwidth is simple: turn off Wifi, turn off 3G. Cutting connection is also simple: turn on wifi, get connected, power off your wifi access point.
I guess you could connect to a Mac (if you had one) setup as a WiFi base station (ad-hoc network). Then on the Mac set up a "dummynet" bandwidth limit and/or high packet loss filter.
That's what I do to simulate the slower higher-latency DSL lines I am making software to setup for Macs.
On the iPhone you can't. One way would be to share your computer WIFI connection to your iPhone but to slow it down using a special application.
This blog post describes some approaches for that:
http://blog.aptivate.org/2010/01/23/make-sure-your-apps-work-in-the-field/
We have a .NET 2.0 desktop application which sends and receives network
packets over UDP.
Several users have reported an occasional socket error 10052 which happens
when the code calls socket.BeginReceiveFrom on a the UDP socket.
What does this mean?
The official MS documentation for socket error 10052 says - quote:
"WSAENETRESET (10052) Network dropped connection on reset . The connection
has been broken due to keep-alive activity detecting a failure while the
operation was in progress. It can also be returned by setsockopt if an
attempt is made to set SO_KEEPALIVE on a connection that has already
failed."
This just doesn't make much sense for a UDP socket since UDP is a
connectionless protocol.
I know that another close error code 10054 in connection with UDP sockets
means that an ICMP message "Port Unreachable" was received, and I am
wondering if 10052 might map to another ICMP message?
I have googled this for months, read network books, etc. but can't find
anything.
Please help - what does socket error 10052 on a UDP socket mean?
Thanks in advance
See http://msdn.microsoft.com/en-us/library/ms740120%28v=vs.85%29.aspx, which describes the recvfrom function. It says of WSAENETRESET (which is winsock error 10052):
For a datagram socket, this error indicates that the time to live has expired.
Be sure that TTL value is high enough, when sending UDP datagrams.
If you are using UdpClient class.
Then use the following before sending the datagram:
myUdpClient.Ttl = 255;
Note: 255 is the maximum value for TTL.
There is some network problem if that value is not enough.
WSAE NET RESET suggests that it happens due to a reset of the network interface itself. Your program is sitting there bound to a UDP port, so in a sense it is connected, but to the network interface rather than to a remote peer.
Try starting your program, getting it to the point where this BeginReceiveFrom call is about to be made, then disable your NIC in the Device Manager and re-enable it. Or, with Wi-Fi, drop and reestablish the connection to the WAP. It might even happen by just unplugging the Ethernet cable to your machine, as recent versions of Windows default to killing all sockets connected through that NIC when this happens.
It would explain the rare problem reports from the field. This probably only happens when there is some local networking fault at the hardware level.