ms/acl_info is a SAP Parameter attribute which is used to control File with access control list for message server information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
File with access authorizations for the message server If this file
exists, it must include all host names, domains, IP addresses and/or
subnetwork masks from which application servers are allowed to log on to
the message server.
The names can be either put in a list or written in separate lines.
Information
This file has no affect on external clients that only want to get
information from the message server. That works the same as before.
The entries must have the following syntax:
HOST = <(><<)>list of names>
Examples
HOST = sapapp1, sappapp2 (only logons from hosts sapapp1 and sapapp2 are
permitted)
HOST = *.sap.com (all hosts from domain sap.com are allowed)
HOST = 157.23.45.56, 157.23.45.57 (Only hosts with these IP addresses
are allowed)
HOST = 157.23.45.* (All hosts from this subnetwork are allowed.)
See SAP Parameter Documentation for full SAP documentation for this profile parameter.