The option of
MaxStartups 10:30:300
in
/etc/ssh/sshd.conf
means that sshd could refuse the 30% of unauthenticated connections according to the
sshd_conf
man page as below.
MaxStartups
Specifies the maximum number of concurrent unauthenticated connections to the SSH daemon. Additional connections will be dropped until authentication succeeds or the LoginGraceTime expires for a connection.
The default is 10:30:100.
Alternatively, random early drop can be enabled by specifying the three colon separated values start:rate:full (e.g. "10:30:60"). sshd(8) will refuse connection attempts with a probability of rate/100 (30%) if there are currently start (10) unauthenticated connections. The probability increases linearly and all connection attempts are refused if the number of unauthenticated connections reaches full (60).
In a Greenplum environment the coordinator host can start a large number of ssh connections to a segment host. If the segment host is not able to authenticate and complete the connections quickly enough, a number of the connections may be denied due to the above explaination of MaxStartups setting.
