Vacm
From Net-SNMP Wiki
Restricting access to a particular index (row) in a Table
Using the view directive in snmpd.conf, one can limit users to a single row in a table. To do this , the optional mask parameter is specified. Here is an excerpt from the man page:
view NAME TYPE SUBTREE [MASK]
The defines the named view. TYPE is either included
or excluded. MASK is a list of hex octets, sepa-
rated by '.' or ':'. The MASK defaults to "ff" if
not specified.
The reason for the mask is, that it allows you to
control access to one row in a table, in a rela-
tively simple way. As an example, as an ISP you
might consider giving each customer access to his
or her own interface:
view cust1 included interfaces.ifTable.ifEntry.ifIndex.1 ff.a0
view cust2 included interfaces.ifTable.ifEntry.ifIndex.2 ff.a0
(interfaces.ifTable.ifEntry.ifIndex.1 == .1.3.6.1.2.1.2.2.1.1.1,
ff.a0 == 11111111.10100000. which nicely covers up and including
the row index, but lets the user vary the field of the row)