Requirements
I have two Ubuntu machines and I want to ECN mark all packets coming out of the first one and detect it in another machine.
Attempt
I modified en-queue of sch_tbf.c (qdisc) and added INET_ECN_set_ce(skb);
I can see inside machine 1 (generator) that ECN is set, but when packets reach the other machine, this mark is disappeared (tos=0).
I was wondering if anyone could help me in implementing this.I enabled forwarding and I see packets reach the second one.I also enabled ECN using proc.
Related
Is it possible at all to read the value (presumably a variable, since it changes every few seconds and is shown on screen) from a process in Windows? This is some custom, fairly old (10y) Windows GUI application that shows values (part counter) from manufacturing machine connected to it via some proprietary protocol (even using a dedicated PCI commmunications card).
I got the idea when reading about people modifying settings in a game (change high-score, change difficulty level, etc).
On Windows, there is an official API ReadProcessMemory for reading data from a process's memory:
ReadProcessMemory copies the data in the specified address range from the address space of the specified process into the specified buffer of the current process. Any process that has a handle with PROCESS_VM_READ access can call the function.
While I am hopeful that it works once the address/offset of the value in question is known, I am not so sure if this application will allocate memory differently when started the next time.
This is how I would approach it:
continuously, e.g. every second
take a screen shot of the application,
take a process dump (procdump from sysinternals) of the application
analyse the process dump and try to find the location/offset of the value in question
compare process dumps from different startups of the application to see if the value is at the same offset
Is this feasible, or is it completely obvious that memory allocation is very dynamic (between restarts and even during runtime) and using an offset-based approach will be doomed?
I would just like to know if the value of "RecievedBroadcasts" for each of the node in Veins also consists of the packets lost or does it just give the number of successful packet receptions. That is if I want to calculate the packet loss ratio, then would it be TotalLostPackets/RecievedBroadcasts or TotalLostPackets/(RecievedBroadcasts + TotalLostPackets).
Thanks for your help
Your best bet to find out exactly how statistics are logged is to look into the source code of Mac1609_4.
You will find that the ReceivedBroadcasts scalar logs the value of variable statsReceivedBroadcasts which is increased via a method called from handleLowerMsg, so only when the Mac layer successfully decoded data.
I have a set of 16 data stored in BRAM ipcore. Now I have to fetch first 4 at a time and give it to the next IPcore (say FFT) for further processing. Once done with this, I have to feed the next set of 4 data. Is the situation handled by state machine? OR how can i assign values from one ipcore to the next ipcore ? Please help!!
BRAM is dual-ported. Simplest is to make a FIFO out of it with one IP core writing and the other IP core reading.
This will not work for an FFT as that requires a special addressing scheme: the data write order is different from the read order. There you need each IP core to make an address and connect it to the two ports of the BPRAM.
In all cases you need handshaking to guarantee reading only starts after the data has been written of course.
Has anybody mentioned data errors, trigger error or upload errors in ChipScope?
I'm using ChipScope (from ISE 14.7) with the IP core flow. So I created 15 different ICON IP cores as ngc files and wrapped them all in a VHDL module. This module chooses by generic with ngc file should be instantiated. So I can easily choose the number of active VIO/ILA cores.
Currently my project has 2 VIO cores and 5 ILA cores, utilizing circa 190 BlockRAMs on a Kintex-7 325T (>400 BlockRAMs in total). When a trigger event occurs, I get sometimes the warning Did not find trigger mark in buffer. Data buffer may be corrupted. or Data upload error.
This error is independent of the trigger mode (normal trigger event, immediate trigger, startup trigger). It seams to happen mostly on Unit 4 (91 bit data * 32k depth + 3 trigger ports each of 4 units). The upload progress bar can stops at any percentage from 1 to 95% as far as I noticed.
Additionally I get hundreds of these warnings:
Xst - Edge .../TransLayer_ILA2_ControlBus<14> has no source ports and will not be translated to ABC.
My google research: ignore them :)
There is also a bug in XST: This warning has no ID and can't be filtered :(
As of now, I tried to fix this problem:
Reduced / Increased JTAG speed -> no effect (program device is not effected)
recompiled ip core / new ngc file
reduced ILA windows size
So what can it be?
P.S. All timings are met.
I found the problem and a solution.
The problem: I changed one ILA coregenerator file's name and it's contents (modified internal name with an editor). But I missed one parameter so CoreGen generated some sources under the old name. This was still in usage by another ILA core, so one of them got overwritten.
Solution:
I opened every ILA xco file and every cgp file and check all names.
This question already has answers here:
How do I calculate network utilization for both transmit and receive
(2 answers)
Closed 2 years ago.
I have a slightly weird problem and I really hope someone can help with this:
I go to university and the wireless network here issues every login a certain quota/week (mine is 2GB). This means that every week, I am only allowed to access 2GB of the Internet - my uploads and downloads together must total at most 2GB (I am allowed access to a webpage that tells me my remaining quota). I'm usually allowed a few grace KB but let's not consider that for this problem.
My laptop runs Ubuntu and has the conky system monitor installed, which I've configured to display (among other things, ) my remaining wireless quota. Originally, I had conky hit the webpage and grep for my remaining quota. However, since my conky refreshes every 5 seconds and I'm on the wireless connection for upwards of 12 hours, the checking of the webpage itself kills my wireless quota.
To solve this problem, I figured I could do one of two things:
Hit the webpage much less frequently so that doing so doesn't kill my quota.
Monitor the wireless traffic at my wireless card and keep subtracting it from 2GB
(1) is what I've done so far: I setup a cron job to hit the webpage every minute and store the result in file on my local filesystem. Conky then reads this file - no need for it to hit the webpage; no loss of wireless quota thanks to conky.
This solution is a win by a factor of 12, which is still not enough. However, I'm a fan of realtime data and will not reduce the cron frequency further.
So, the only other solution that I have is (2). This is when I found out about wireshark and it's commandline version tshark. Now, here's what I think I should do:
daemonize tshark
set tshark to monitor the amount (in KB or B or MB - I can convert this later) of traffic flowing through my wireless card
keep appending this traffic information to file1
sum up the traffic information in the file1 and subtract it from 2GB. Store the result in file2
set conky to read file2 - that is my remaining quota
setup a cron job to delete/erase_the_contents_of file1 every Monday at 6.30AM (that's when the weekly quota resets)
At long last, my questions:
Do you see a better way to do this?
If not, how do I setup tshark to make it do what I want? What other scripts might I need?
If it helps, the website tells me my remaining quota is KB
I've already looked at the tshark man page, which unfortunately makes little sense to me, being the network-n00b that I am.
Thank you in advance.
Interesting question. I've no experience using tshark, so personally I would approach this using iptables.
Looking at:
[root#home ~]# iptables -nvxL | grep -E "Chain (INPUT|OUTPUT)"
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
Chain OUTPUT (policy ACCEPT 9763462 packets, 1610901292 bytes)
we see that iptables keeps a tally of the the bytes that passes through the each chain. So one can presumably go about monitoring your bandwidth usage by:
When your system starts up, retrieve your remaining quota from the web
Zero the byte tally in iptables (Use the -z option)
Every X seconds, get usage from iptables and deduct from quota
Here are some examples of using iptables for IP accounting.
Caveats
There are some drawbacks to this approach. First of all you need root access to run iptables, which means you need conky running as root, or run a cron daemon which writes the current values to a file which conky has access to.
Also, not all INPUT/OUTPUT packets may count towards your bandwidth allocation, e.g. intranet access, DNS, etc. One can filter out only relevant connections by matching them and placing them in a separate iptables chain (examples in the link given above). An easier approach (if the disparity is not too large) would be to occasionally grab your real time quota from the web, reset your values and start again.
It also gets a little tricky when you have existing iptables rules which are either complicated or uses custom chains. You'll then need some knowledge of iptables to retrieve the right values.