The rewrite plugin

The rewrite plugin can change SNMP response values into something different by applying a regular expression.

Plugin options

One or more options could be passed to the plugin via the plugin-options server and/or client configuration option.

The values to the plugin-options setting must be one or more key-value pairs separated via the equal sign (=). The following plugin options are recognized.

config

Path to plugin configuration file.

This option can reference config-dir macro.

Configuration syntax

The rewrite plugin configuration file consists of zero or more lines. Each line has four fields:

  1. Regular expression pattern matching OIDs in response PDU
  2. Regular expression pattern matching string representation of a value associated with the matched the OID
  3. Substitution expression as in re.sub
  4. Maximum substitutions count (zero disables the limit)

String fields must be quoted (“).

For each matching OID in SNMP response PDU, the value is run through substitution function. If substitution yields empty string, type-specific <empty> value is returned. That can be zero for integers, empty string for texts and 0.0 for OIDs.

Example configuration

The following example appends arbitrary string to whatever value is returned for SNMPv2-MIB::sysDescr.0:

"^1\.3\.6\.1\.2\.1\.1\.1\.0$" "(.*)" "\\1 (SNMP Proxy is watching you)" 0

This snippet resets values for all SNMPv2-MIB::system OIDs:

"^1\.3\.6\.1\.2\.1\.1.*$" ".*" "" 0

For more information please refer to the full configuration example.