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4:38 AM

Why is it I never seem to accurately predict which questions will get a lot of attention?

Q: Server admin sent me their private key. Why?

I'm kind of new to ssh so forgive me if this is a stupid question. I'm supposed to be accessing a server in order to link a company's staging and live servers into our deployment loop. An admin over on their side set up the two instances and then created a user on the server for us to ssh in as....

I was sure that was a throwaway answer that might get one, maybe two votes at most.

10 hours later…

Jeff Schaller

2:28 PM

@Wildcard HNQ feels a little surreal - it's a wild ride when a Q gets picked up! Nice answer!

5 hours later…

Aaron Hall

7:55 PM

discussion of /dev/random vs /dev/urandom - "Myths about urandom"

Gilles

137

Q: Is a rand from /dev/urandom secure for a login key?

Lets say I want to create a cookie for a user. Would simply generating a 1024 bit string by using /dev/urandom, and checking if it already exists (looping until I get a unique one) suffice? Should I be generating the key based on something else? Is this prone to an exploit somehow?

cryptography web-application authentication linux random

the two say pretty much the same things and AFAIK were written independently

both have been cited a lot on SE, by me and others

terdon

@Gilles That was a really great answer. I don't know the first thing about cryptography but still found it very informative.

derobert

8:46 PM

@terdon it's amazing how many portability problems you can find with a simple df :-/

terdon

@derobert Not really. it's amazing how many portability problems you can find with a simple df :-/

derobert

hah

I'm sure StéphaneChazelas could find at least a dozen more. And provide us a thorough historical discussion of each.

And somehow make all of that interesting.

terdon

Wouldn't be susprised :)

Aaron Hall

9:24 PM

Looks like vim's getting native package management? shapeshed.com/vim-packages

terdon

will not start an editor flame war. will not start an editor flame war. will not start an editor flame war. will not start an editor flame war.

Aaron Hall

That's a good mantra.

Just remember there's lots of other posts in the sea.

terdon

Aaron Hall

I want to spit out 10 random bytes, separated by spaces. Here's what I have so far:

cat /dev/urandom | hexdump -v -e '/1 "%u "' | cut -d " " -f 1-10

but it no works.

is borken

terdon

@AaronHall It hangs. It probably will work if you wait long enough, but just pass it through head:

cat /dev/urandom | hexdump -v -e '/1 "%u "' | head -c 50  | cut -d " " -f 1-10

Aaron Hall

9:33 PM

that will do it. :)

I didn't realize head had the -c argument

cat /dev/urandom | head -c 10 | hexdump -v -e '/1 "%u "'

terdon

Yeah, comes in handy for this sort of thing.

@AaronHall Even better.

Aaron Hall

head -c 10 /dev/urandom | hexdump -v -e '/1 "%u "'

removed redundant use of cat

Aaron Hall

10:01 PM

Useless use of cat award

2 hours later…

Jamjar91

11:52 PM

Hi guys, I'm learning how to use bash to write my first script for college, but I'm having trouble with nested statements/loops/functions. I'm trying to write an if statement where if a variable value is true, it breaks/returns out of that if statement, then also breaks out of a containing while loop, that is also part of a function, that I want to end (when the if statement's variable is true).

I've tried return N, break N, and exit (I know know this just ends the script.)

Can anyone shed any knowledge on how this should work please?

Gilles

A: Capturing key input from events device and mapping it (toggle TouchPad key is unmapped)

As it turns out the kernel did pick it up, but kept complaining that it's not recognised. For anyone else having this issue, or wants to map a key that's not read by the OS, read on. Open a terminal and run dmesg | grep -A 1 -i setkeycodes. This will give you multiple entries like this: [ 9...

^^^^ upvote plz

my answer is somewhat useful so I won't delete it, but the asker's self-accepted answer is the right answer to this question and should be sorted first

@Jamjar91 ask on the site. Post your actual, complete script.

Jamjar91

@Giles will do, thank you. :)

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