OID value: 1.3.6.1.2.1.6.4
OID description:
tcpMaxConn OBJECT-TYPE SYNTAX INTEGER ACCESS read-only STATUS mandatory DESCRIPTION "The limit on the total number of TCP connections the entity can support. In entities where the maximum number of connections is dynamic, this object should contain the value -1." ::= { tcp 4 }
See also the OID Repository website reference for 1.3.6.1.2.1.6.4