Information
The DB2RSHCMD registry varible specifies the remote shell command to use when starting remote database partitions and with the db2_all script to run utilities and commands on all database partitions. It is recommended that a value be used which encrypts the data sent between partitions, such as ssh.
Rationale:
The traditional rsh command sends all its data, including passwords, in plaintext between partitions. An attacker who can read network traffic may have access to these passwords and other data. Specifying a remote shell command, such as ssh encrypts the data sent over the network.
Impact:
Enabling this value without configuring public and private keys may result in an inability to start or stop Db2 across all partitions without manually issuing db2start/db2stop individually on each partition.
Solution
Follow the guidance on this page to create public and private keys for ssh:
https://www.ibm.com/docs/en/db2/11.5?topic=installation-enabling-execution-remote-commands
Run the following command to set the DB2_RSHCMD registry variable to ssh:
db2set DB2RSHCMD=ssh
Default Value:
In Db2 V11.5 Mod Pack 5 or earlier, the default value is rsh.
In Db2 V11.5 Mod Pack 6 or later, the default value is ssh.