Messages in this thread | | | Date | Sat, 23 Oct 1999 17:31:13 -0600 (MDT) | From | Todd <> | Subject | RFC: fragmentation code experiment |
| |
hi,
i am working on a project related to the linux networking code and wanted comments both on the project, in general, and on methodology.
here is the general set of premises:
1) the code related to fragmentation and (especially) reassembly and (especially) out-of-order reassembly is some of the more complicated and difficult-to-get-right code in the IP portion of the networking code. this code has, over the course of the past year or two, also been responsible for security (denial of service) and other problems.
2) modern networks almost never produce out-of-order fragments for packets that are eventually accepted (this is a premise--needs to be tested).
3) workstations and server that do no fragment reassembly or at least no out-of-order fragment reassembly would have simpler (and better-performing) network code.
4) if fragment reassembly (out-of-order or not) needs to be done, it should be done by border routers (where people are increasingly willing to do computationally intensive stuff like filter and reassemble fragments).
so the general plan is to test some of these premises in the following ways.
add a sysctl (i haven't yet figured out how to do that) to log the entry into the sections of code that i am interested in: fragments being reassembled, fragments out-of-order being reassembled, packets being dropped.
create a log-processing script that correlates and counts the above kinds of events. in particular, count how many packets are received as out-of-order fragments but are eventually accepted (which i am assuming will almost never happen, but need to test).
i would be interested in suggestions about how to best implement this (including any guidance for adding a sysctl; i have read the documentation and some of the code, but i don't understand it yet; also interesting questions: does anyone agree with my premises about the state of the fragment code or have other perspectives). i'd also be interested in other general thoughts about the project.
thanks, in advance for comments on this,
todd underwood todd@unm.edu
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |