I am struggling to integrate the network stack of Linux Kernel 2.6.35 with the Network Simulation Cradle (http://www.wand.net.nz/~stj2/nsc/).
Has anyone done it before ? If yes please reply.
I am getting an error saying : fatal error: when writing output to : Broken pipe.
Well, I cannot proceed further explaining what I have done till now, as that would make no sense if no one here has worked with this Network Simulation Cradle.
So, if anyone has worked with this, please reply.
Regards
You're probably better asking off on the ns-3 mailing list, or emailing the author of the NSC directly.
Either way, you'll need to include more information in your question!
Related
I am still leaning python and Nornir for network automation as a network engineer.
I am scripting to find any BGP issue from multiple devices with Nornir using "TextFSM".
The python with nornir works correctly without "TextFSM.
I get an error message when TextFSM is used for parsing.
I searched and spent time a lot to find the reason of this issue.
Half of the network devices I am managing has the issue with "TextFSM" at present.
Could you please advise me where I can start to fix this issue?
Thank you.
I get the output with netmiko like below
output = net_connect.send_command('show ip bgp summary')
Here is the output of "print(repr(output))
I am trying to make a Mini-Game Library with some multiplayer games. I would like to do it so everyone can just create a lobby which runs on their PC and other people can connect to it.
I am really unsure on how to approach it because I'm not experienced with Godots High-Level Networking and everything else network related I did was in Node.js with a public server always running and handeling all the connections.
I would just like some tips on how to start setting something like this up.
Thanks in advance ^^
Checkout the example(s) on https://github.com/godotengine/godot-demo-projects of which /networking/multiplayer_bomber fits your needs best I guess
I am trying to do an assignment (from another univ's coursepage) which has a line in the starter code (Python with mininet) as
os.system("rmmod tcp_probe; modprobe tcp_probe full=1")
Popen("cat /proc/net/tcpprobe > %s" % (outfile), shell=True)
which gives an error saying that tcp_probe has been disabled.
I found out by googling that tcp_probe has been deprecated in the linux kernel. However it just asks me to 'do the same using ftrace'. I have tried searching online but could not find out how to use ftrace to achieve the same.
Any help is appreciated.
tldr;
Unfortunately, I could not find any way to get TCP tracepoints to work in Mininet, which is what ftrace would uses. The reason for this is that the mininet's /sys/kern/debug directory is empty, i.e., tracing cannot be enabled.
Options:
1. Using mininet-tracing (not recommended)
There probably is a way to get the kernel to include this, or you could use https://github.com/mininet/mininet-tracing which might get you what you need, but I have seen reports that it is slow, and has been updated 9 years ago...
2. Writing a new kernel module (I have tested this and it works)
What I found as a solution instead, was to force printing for the TCP I had in mind and then take a look at the results that way. In order to enable this, you would essentially need to extend some of TCP's behaviour and (quite possibly) reuse the TCP module you have in mind. And create a new kernel module.
Here I have provided an example that you can use. It logs socket information on each ACK. I also included a Makefile and a script to load/unload the kernel module. After you enable the module and let some traffic flow (assuming you are on a debian-based linux) you should be able to find the logs of your TCP in /var/log/kern.log.
Note:
This is a hacky way around the issue, but was good enough for my needs, and hopefully can help someone else too.
Just because of curiosity, I'd like to get to know better, how the Internet works.
I have already read quite some articles in Wikipedia, but these are very theoretical. I know, which protocols are used where, and what they are good for (IP, TCP, HTTP). But I have no idea how these are actually implemented in Linux or any other OS.
So, for me to understand these things better, I'd like to write a simple implementation of the Echo-Protocol in C, preferrably for Linux, and from ground up. My client-application should be able to send a message to a given port on any other computer, and my server-application should be able to receive this message, and send it back to the client.
Where do I start best? What should I read to get more information on these topics? Has anyone of you already done something like this, and if so, what did you learn?
In addition, it would be great if someone could tell me a bout a program that shows me the raw Internet-traffic that runs trough my PC. I think this would also help me understanding things a bit better.
Thanks in advance for your advice.
http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=berkley+socket+tutorial
http://beej.us/guide/bgnet/
http://www.tenouk.com/cnlinuxsockettutorials.html
http://www.paulgriffiths.net/program/c/sockets.php
In addition, it would be great if someone could tell me a bout a program that shows me the raw Internet-traffic that runs trough my PC.
Ethereal is pretty great for this.
Hey guys, I'm new to UNIX, trying to teach myself and came across this practice question in the book im using. My guess is that the program terminating simply calls the exit function if an invalid input is passed to it. Please let me know if I'm on the correct path! Thanks guys!
That's one way for a program to terminate. If you call exit with a non-zero number, the program will have "exited normally with error status". There are other ways. If someone kills the process, it will die abnormally. If the program segfaults (accesses an address that isn't mapped to it), it'll be killed with SIGSEGV.
That answers the question of "what causes a program to terminate". That doesn't quite answer "what process is undertaken", which probably means "what does the kernel do when a program crashes?" I don't know all the gory details, but I know that when a program does something illegal, it doesn't (unless there's a bug in the kernel or something) corrupt memory of any other part of the system, it just stops the program from running and returns the resources it was using to the system.