This assumes you have already used the define channel or alter channel commands to give a user access to a channel. For example, let's say user JohnDoe has been granted access to CHANNEL01. These examples are based on Linux. Switch to the mqm user.
su - mqm
Start the MQSC utility for the queue manager that you want to alter the server connection channel. In this example, MANAGER01 is the name of the queue manager. If you are not sure the name of the queue manager, use the dspmq command to display the queue managers. This assumes that the "mqm" users .bash_profile has been updated to have PATH=$PATH:<root installation directory>/bin.
The display chlauth command can be used to display the access to a channel.
echo "display chlauth (CHANNEL01)" | runmqsc MANAGER01
Take for example the following output. In this example, since ADDRESS is a wildcard, access from all IP addresses is allowed.
CHLAUTH(CHANNEL01) ADDRESS(*) DESCR( ) CUSTOM( ) USERSRC(CHANNEL) CHCKCLNT(ASQMGR) ALTDATE(2018-12-07) ALTTIME(15.12.34)