Hi All
I don't know whether i am asking on a correct list or not i have a query that how to know that what system call are called when packet enters the system or when we send a packet from a system?
Thanks
Robert Clove wrote:
Hi All
I don't know whether i am asking on a correct list or not i have a query that how to know that what system call are called when packet enters the system or when we send a packet from a system?
Hi, there. Sounds like you want to do a tcpdump, or some such, on eth0 (or whatever).
mark
Tcpdump won"t tell the system calls
On Saturday, December 7, 2013, wrote:
Robert Clove wrote:
Hi All
I don't know whether i am asking on a correct list or not i have a query that how to know that what system call are called when packet enters the system or when we send a packet from a system?
Hi, there. Sounds like you want to do a tcpdump, or some such, on eth0 (or whatever).
mark
CentOS mailing list CentOS@centos.org javascript:; http://lists.centos.org/mailman/listinfo/centos
Robert Clove wrote:
On Saturday, December 7, 2013, wrote:
Robert Clove wrote:
I don't know whether i am asking on a correct list or not i have a query that how to know that what system call are called when packet
enters
the system or when we send a packet from a system?
Hi, there. Sounds like you want to do a tcpdump, or some such, on eth0 (or whatever).
Tcpdump won"t tell the system calls
If you know the process, you could use strace.
mark (in the US, where it's still 6 Dec)
On 12/6/2013 11:34 AM, m.roth@5-cent.us wrote:
If you know the process, you could use strace.
that will only show user mode calls, which are basically select() and read(). as I said, the packet transversal is all done in the network related kernel modules, under the covers where strace can't see it. you'd need to use a kernel debugger to follow it, and good luck.
On 12/6/2013 11:28 AM, m.roth@5-cent.us wrote:
I don't know whether i am asking on a correct list or not i have a query
that how to know that what system call are called when packet enters the system or when we send a packet from a system?
Hi, there. Sounds like you want to do a tcpdump, or some such, on eth0 (or whatever).
um, no, that wouldn't answer his question.
when a packet is recieved by a NIC, it generates a hardware interrupt, which triggers a kernel driver interrupt handler, this will use various kernel level APIs which aren't visible to user space, and bubbles through the various layers of the network stack, before its finally presented to the user mode application which is waiting for it via a read or select call.
the specifics of the kernel mode stuff is outside the scope of this list. actually, this whole question is outside the scope of this list as its really not centos specific at all, its a general Linux kernel question. I don't know what the appropriate forum for such might be, however.
John R Pierce wrote:
On 12/6/2013 11:28 AM, m.roth@5-cent.us wrote:
I don't know whether i am asking on a correct list or not i have a query that how to know that what system call are called when packet
enters
the system or when we send a packet from a system?
Hi, there. Sounds like you want to do a tcpdump, or some such, on eth0 (or hatever).
um, no, that wouldn't answer his question.
when a packet is recieved by a NIC, it generates a hardware interrupt,
<snip> Right, we mostly all know that. But from his original query, I wasn't sure what he wanted... for that matter, I'm still not sure.
mark
Tcpdump won"t tell the system calls
On Saturday, December 7, 2013, wrote:
Robert Clove wrote:
Hi All
I don't know whether i am asking on a correct list or not i have a query that how to know that what system call are called when packet enters the system or when we send a packet from a system?
Hi, there. Sounds like you want to do a tcpdump, or some such, on eth0 (or whatever).
mark
CentOS mailing list CentOS@centos.org javascript:; http://lists.centos.org/mailman/listinfo/centos
On Fri, Dec 6, 2013 at 12:25 PM, Robert Clove cloverobert@gmail.com wrote:
Hi All
I don't know whether i am asking on a correct list or not i have a query that how to know that what system call are called when packet enters the system or when we send a packet from a system?
Thanks
This link might help:
http://sercanbilgic.com/2013/08/16/20-linux-system-monitoring-tools-every-sy...
Some of the tools there have been mentioned.
-wes
On 6 December 2013 19:25, Robert Clove cloverobert@gmail.com wrote:
Hi All
I don't know whether i am asking on a correct list or not i have a query that how to know that what system call are called when packet enters the system or when we send a packet from a system?
These slides might help you with your googling:
http://www.cs.odu.edu/~csi/tcpipstack.ppt
And this might go some way to explaining things...
http://lwip.wikia.com/wiki/Writing_a_device_driver
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