I hope this is no intrusion to this list or that it is off-topic, however, I
will try to keep it as much to the core ipv4 area as possible. If you do
respond, please CC replies directly to me since I am not on the list.
First off, I'm working on a larger document which contains a reference to all
ipv4 sysctl calls available in linux. The reference part of the document is
heavily based upon linux/Documentation/networking/ip-sysctl.txt document
written by various writers, as it looks now. The main problem is that I have
quite a problem understanding the behaviours of some variables/sysctl calls,
and what they do.
I will (try to :-)) briefly sum up all questions I have at this moment below:
ip_nonlocal_bind - how does this affect the ip stack? How and why will it break
certain applications (according to ip-sysctl.txt)? A possible scenario when it
may be used?
INET peer storage - one of the subtopics from the ip-sysctl.txt. What does this
refer to? ARP tables and storage I assume, but I am not 100% sure? Would anyone
care to give a very very brief explanation to this "section" and why a specific
subsection on this in the document, but not
tcp_max_syn_backlog - I haven't looked in the source code for this one myself,
but the default values listed in the ip-sysctl.txt document are faulty in
comparison to the default values I get on my own systems. Are these calculated
at boot time, or is the document simply old?
tcp_fack - Does this variable turn on Fast Acknowledgement, and if so, in which
RFC is this documented? RFC 2018, 2883 or some other?
tcp_reordering - What does it mean? How does it work? Is there any RFC
documenting this and what the default behaviour should be?
tcp_adv_win_scale - I can say nothing but "hmmm" about the explanation in the
ip-sysctl.txt document, and I understand pretty much nothing from what I've
read in the source, though I haven't even tried very much so far. What do the
different equations do as specified in ip-sysctl.txt? What do the variables
used in them mean? Perhaps I'm just dumb or something :-).
icmp_ratemask - Both these are interconnected afaik, but they are not listed in
the ip-sysctl.txt (seems they override the old variables that where available).
From what I understand, ratemask tells which ICMP types (and codes?) are
specified, and if to ratelimit these. How is this mask calculated? How is the
ratelimit set, and in what measurement?
Those are the questions I have for now.. Sorry for the massive amount of
questions, but I have collected them for a week or so :-). I really really hope
this is not offtopic for this list and that noone will get too annoyed over the
questions and that someone is able to reply to them.
Have nice day,
PS. I will be gone over the weekend so there is no rush with any replies
really, just thought I'd get them away before the list of questions grows too