SSH-RAND-HELPER(8) System Manager's Manual SSH-RAND-HELPER(8)

ssh-rand-helper —
Random number gatherer for OpenSSH

ssh-rand-hlper [-vxXh] [-b bytes]

ssh-rand-helper is a small helper program used by ssh(1), ssh-add(1), ssh-agent(1), ssh-keygen(1), ssh-keyscan(1) and sshd(8) to gather random numbers of cryptographic quality if the openssl(4) library has not been configured to provide them itself.

Normally ssh-rand-helper will generate a strong random seed and provide it to the calling program via standard output. If standard output is a tty, ssh-rand-helper will instead print the seed in hexidecimal format unless told otherwise.

ssh-rand-helper will by default gather random numbers from the system commands listed in /etc/ssh/ssh_prng_cmds. The output of each of the commands listed will be hashed and used to generate a random seed for the calling program. ssh-rand-helper will also store seed files in ~/.ssh/prng_seed between executions.

Alternately, ssh-rand-helper may be configured at build time to collect random numbers from a EGD/PRNGd server via a unix domain or localhost tcp socket.

This program is not intended to be run by the end-user, so the few commandline options are for debugging purposes only.

bytes
Specify the number of random bytes to include in the output.
Output a hexidecimal instead of a binary seed.
Force output of a binary seed, even if standard output is a tty
Turn on debugging message. Multiple -v options will increase the debugging level. -h Display a summary of options.

Damien Miller <djm@mindrot.org>

ssh(1), ssh-add(1), ssh-keygen(1), sshd(8)
April 14, 2002 BSD