I would like to know why e.g. linux uses 20 second timeout for socket connect. I can't find any information myself so I'm curious if anyone knows better sources or happens to know the rational off-hand. Are questions about historical purpose of a given unix/linux facet generally too broad? Or is there a way I can improve my question?
Your questions were put On Hold as too broad
too broad - if your question could be answered by an entire book, or has many valid answers (but no way to determine which - if any - are correct), then it is probably too broad for our format
Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question.
I think that having one specific question would be a good start.
I'd rephrase it as follows:
Linux uses 20 seconds as default network timeout
- What is the reason for this specific timeout value?
Note that: java and bsd use different values for the network timeout (30 for java and ~75 for bsd)
If you have any references for the timeout values you mentioned, I'd add those references as a note.