Is /dev/random really my problem?

Sebastian Hagedorn Hagedorn at
Mon Apr 7 03:54:15 EDT 2003


every now and then it becomes impossible to log in to our cyrus-imapd 
2.1.12 server using IMAP under RedHat AS 2.1. POP sessions appear to be 
unaffected. The symptom is that a connection to port 143 is accepted but 
that it then takes several minutes until the server shows its banner and 
prompt. This condition can last for several minutes, but eventually the 
server becomes unstuck.

My current working hypothesis is that this behavior is caused by a lack of 
entropy from /dev/random for the SASL library. I know that I could change 
config.h to use /dev/urandom. However, I'm sceptical for the following 

- there are only about 10 users altogether; does entropy really run out so 
- from what I've read I thought that "cat /dev/random" would block in these 
instances. It does not.
- POP seems to be unaffected.

Given this data, is it at all conceivable that /dev/random is really the 
issue here? If it isn't, what would be the best way to debug this? I tried 
using strace, but wasn't really sure *what* to strace.

Thanks, Sebastian Hagedorn
Sebastian Hagedorn M.A. - RZKR-R1 (Gebäude 52), Zimmer 18
Zentrum für angewandte Informatik - Universitätsweiter Service RRZK
Universität zu Köln / Cologne University - Tel. +49-221-478-5587
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