sendmail, 4th Edition

RandFile

Source for random numbers V8.11 and later

STARTTLS requires that it have some source for randomized data. It uses /dev/urandom on systems that support that device. On systems that don’t, you must specify an alternative.

The RandFile option is used to specify an alternative source like this:

O RandFile=where                  ← configuration file (V8.11 and later)
-ORandFile=where                  ← command line (V8.11 and later)
define(`confRAND_FILE',`where')   ← mc configuration (V8.11 and later)

Here, where is of type string, and specifies the source for the randomized data. That source can be either a Unix-domain socket used by the egd(8) daemon (EGD on page 204), or a file you update with randomized data yourself (Roll your own on page 204). You tell sendmail which you are using by prefixing where with either a literal egd: or file: expression:

define(`confRAND_FILE',`egd:/var/run/entropy')   ← socket for the egd daemon
define(`confRAND_FILE',`file:/etc/randfile')     ← a file of random data

See Roll your own on page 204 for a full discussion of how this option and those file types fit into the STARTTLS scheme.

The RandFile option is not safe. If specified from the command line, it can cause sendmail to relinquish its special privileges.