MIDCOM-MIB

MIB Reference — IPNetwork Monitor · Updated October 06, 2026

All MIBs › MIDCOM-MIB

Organization: IETF Middlebox Communication Working Group

Last Updated: 2007-08-09

Category: VPN and Security

Description: Defines managed objects for controlling middlebox devices such as firewalls and NATs via SNMP.

IPNetwork Monitor uses several OIDs from this MIB in network discovery and polling the applicable devices. Start monitoring MIDCOM-MIB with a free 30-day trial of IPNetwork Monitor.

What Is MIDCOM-MIB?

MIDCOM-MIB is an IETF standards-track module defining objects for configuring middlebox devices such as firewalls and network address translators (NATs) through the MIDCOM protocol described in RFC 3304 and RFC 3989. It groups objects into transaction, configuration, and status categories, centered on a rule table that represents individual firewall/NAT policy rules. It is used to monitor the operational health of middlebox rule enforcement: rule administrative versus operational status shows whether a policy is actually active, and a dedicated error object surfaces rule failures, while storage-type and idle-timeout objects reveal how long a rule or its associated pinhole persists. It builds directly on the MIDCOM protocol semantics and transaction model rather than on a separate hardware MIB. It is typically deployed in carrier or enterprise networks where an external MIDCOM agent dynamically opens firewall/NAT pinholes for applications like VoIP or multimedia signaling. Engineers implementing or auditing this functionality typically reference the MIDCOM-MIB RFC/standard documentation for the authoritative specification.

IPNetwork Monitor allows you to monitor SNMP objects defined in MIDCOM-MIB. Use the built-in SNMP Monitoring Browser to explore available variables, view their current values and descriptions, and select the objects you want to monitor. You can then create SNMP monitors, configure thresholds, and receive alerts when monitored values change.

Supported Devices

  • Firewall/NAT middlebox
  • vendor-neutral, standards-based MIB, not tied to a specific manufacturer

Monitoring Examples

An operator polls midcomRuleTable (midcomRuleEntry, indexed by midcomRuleIndex) and compares midcomRuleAdminStatus against midcomRuleOperStatus to find rules that were requested but never activated, then checks midcomRuleError to see why. midcomRuleInterface and midcomRuleFlowDirection identify which interface and traffic direction a rule governs, while midcomRuleMaxIdleTime shows how soon an idle pinhole will be torn down; midcomNotifications would alert on state changes to these rules.

What Can Be Monitored

  • rule admin status
  • rule operational status
  • rule errors
  • rule storage type/time
  • rule interface and flow direction
  • rule max idle time
Imported Objects

From IF-MIB

InterfaceIndexOrZero

From INET-ADDRESS-MIB

InetAddress
InetAddressPrefixLength
InetAddressType
InetPortNumber

From NAT-MIB

NatBindIdOrZero

From SNMP-FRAMEWORK-MIB

SnmpAdminString

From SNMPv2-CONF

MODULE-COMPLIANCE
NOTIFICATION-GROUP
OBJECT-GROUP

From SNMPv2-SMI

Counter32
Gauge32
MODULE-IDENTITY
NOTIFICATION-TYPE
OBJECT-TYPE
Unsigned32
mib-2

From SNMPv2-TC

RowStatus
StorageType
TEXTUAL-CONVENTION
TruthValue

How to Use in IPNetwork Monitor

Example using midcomTotalRejectedRuleEntries OID:

Select a device implementing MIDCOM-MIB as the target host to create a monitor — the SNMP service should be up and running on it. Click New Monitor, then check SNMP Custom on the Favorites tab, click Next, and confirm the host. On the next page, click Select... to open the built-in SNMP MIB Browser and type midcomTotalRejectedRuleEntries into the Find box to locate it in the OID tree, then select it and click OK. The total number of failed attempts to create an entry in the midcomRuleTable. On the monitor's Main parameters page you can set the target's SNMP port (default 161), credentials, polling interval, and other settings — see the SNMP Monitor help for details. On the State conditions and Alerting tabs, configure when the monitor should change state and trigger an alert; since this is a Counter32-type OID, Value bounds is the most useful condition here — trigger an alert if the counter increases between polls, since a rising count of errors, failures, or discards often points to a real underlying problem. Click Finish to create the monitor; you can adjust any parameter later.
OIDs

RFC description

Middlebox communication management for firewalls and network address translators using MIDCOM protocol for policy configuration.

Start monitoring Vendor-neutral IETF standard (firewall/NAT middlebox, MIDCOM protocol) with a free 30-day trial of IPNetwork Monitor. Import MIBs, browse SNMP OIDs, create custom SNMP monitors, configure alerts, and monitor any SNMP-enabled network device from a single console.

Download MIDCOM-MIB