Is there a way to decrease the entropy pool?

Is there a way to decrease the entropy pool?

Secondly, AFAIK (I haven’t tested these commands) you can decrease the entropy pool by setting the appropriate variable in /proc. To set it to 32 bits: cat /dev/random will continuously use up entropy as it becomes available, keeping it at or near zero. It’s not perfect, but it’s simple.

What does the entropy _ avail field in ASLR mean?

The entropy_avail field reads the input_pool.entropy_count, the “output” pool refers to the pool used for urandom (non-blocking pool) and random (blocking pool). As mentioned in this answer, spawning new processes consumes entropy for things like ASLR.

How to check the entropy of a system?

First of all, you should make sure that it’s really the depletion of the random pool that produces the bug in your software. You can run cat /proc/sys/kernel/random/entropy_avail to test the available entropy on your system and check if it hits zero.

Why do I keep losing bits of entropy?

For monitoring the entropy pool without draining it you can try the entropy-watcher program (see linked answer). Watching the entropy-watcher numbers closely it seems that you lose about 64 bits of entropy at intervals. Based on the analysis in the other answer, this seems to be the result of moving entropy to an “output pool” to avoid wasting it.

How does the entropy pool in Linux work?

In this context, your entropy pool is just a bunch of random bytes, where one cannot be derived from the previous, or any of the others. Which means you have high entropy.

How to create a random entropy pool in web server?

On a web-server you can combine server data (HW, SW, performance), client data (user-agent, request-time, cookie, URL variables, whatever you can gather), some external data (like random.org), mix everything with let say sha1 (mixed_data + time + some_secret_key) and you get fairly unpredictable bits of random data.