---
name: "gensnmptree"
section: "1"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/gensnmptree"
---

# gensnmptree(1)

generate C and header files from a MIB description file

## NAME

**gensnmptree** – generate C and header files from a MIB description file

## SYNOPSIS

**gensnmptree** \[**-dEeFfhlt**\] \[**-I** *directory*\] \[**-i** *infile*\] \[**-p** *prefix*\] \[*name* *...*\]

## DESCRIPTION

The **gensnmptree** utility is used to either generate C language tables and header files from a MIB description or to numeric OIDs from MIB descriptions. The first form is used only for maintaining the [bsnmpd(1)](/bsnmpd/1.md) daemon or for module writers. The second form may be used by SNMP client program writers.

If none of the options **-e**, **-E** or **-t** are used **gensnmptree** reads a MIB description from its standard input and creates two files: a C-file *prefix*tree.c containing a table used by [bsnmpd(1)](/bsnmpd/1.md) during PDU processing and a header file *prefix*tree.h containing appropriate declarations of the callback functions used in this table, the table itself and definitions for all enums.

The following options are available:

- **-d**

  Switch on debugging.

- **-E**

  Extract enumerations and bit constructs. In this mode the tool emits a header file that contains for each type given on the command line a C-enum definition and a preprocessor define that may be used to map values to strings.

- **-e**

  **gensnmptree** expects MIB variable names (only the last component) on its command line. It reads a MIB specification from standard input and for each MIB variable name emits three C preprocessor defines on its standard output:

  - *OIDX\_**name*

    This define can be used to initialize a *struct* *asn\_oid* in the following way:

    ```
    const struct asn_oid oid_sysDescr = OIDX_sysDescr;
    ```

  - *OIDLEN\_**name*

    is the length of the OID.

  - *OID\_**name*

    is the last component of the OID.

- **-F**

  emit definitions for C-functions includeable in a C-file that do some basic stuff on enums like value checking and conversion between value and strings.

- **-f**

  emit definitions for inline C-functions that do some basic stuff on enums like value checking and conversion between value and strings.

- **-h**

  Print a short help page.

- **-I** *directory*

  Add the named directory to the include path just before the standard include directories.

- **-i** *infile*

  Read from the named file instead of standard input.

- **-l**

  Generate local preprocessor includes. This is used for bootstrapping [bsnmpd(1)](/bsnmpd/1.md).

- **-t**

  Instead of normal output print the resulting tree.

- **-p** *prefix*

  Prefix the file names and the table name with *prefix*.

## MIBS

The syntax of the MIB description file can formally be specified as follows:

```
 file := top | top file
 top := tree | typedef | include
 tree := head elements ')'
 entry := head ':' index STRING elements ')'
 leaf := head type STRING ACCESS ')'
 column := head type ACCESS ')'
 type := BASETYPE | BASETYPE '|' subtype | enum | bits
 subtype := STRING
 enum := ENUM '(' value ')'
 bits := BITS '(' value ')'
 value := INT STRING | INT STRING value
 head := '(' INT STRING
 elements := EMPTY | elements element
 element := tree | leaf | column
 index := type | index type
 typedef := 'typedef' STRING type
 include := 'include' filespec
 filespec := '"' STRING '"' | '<' STRING '>'
```

*BASETYPE* specifies a SNMP data type and may be one of

- NULL

- INTEGER

- INTEGER32 (same as INTEGER)

- UNSIGNED32 (same as GAUGE)

- OCTETSTRING

- IPADDRESS

- OID

- TIMETICKS

- COUNTER

- GAUGE

- COUNTER64

*ACCESS* specifies the accessibility of the MIB variable (which operation can be performed) and is one of

- GET

- SET

*INT* is a decimal integer and *STRING* is any string starting with a letter or underscore and consisting of letters, digits, underscores and minuses, that is not one of the keywords.

The *typedef* directive associates a type with a single name.

The *include* directive is replaced by the contents of the named file.

## EXAMPLES

The following MIB description describes the system group:

```
include "tc.def"
typedef AdminStatus ENUM (
	1 up
	2 down
)
(1 internet
  (2 mgmt
    (1 mib-2
      (1 system
        (1 sysDescr OCTETSTRING op_system_group GET)
        (2 sysObjectId OID op_system_group GET)
        (3 sysUpTime TIMETICKS op_system_group GET)
        (4 sysContact OCTETSTRING op_system_group GET SET)
        (5 sysName OCTETSTRING op_system_group GET SET)
        (6 sysLocation OCTETSTRING op_system_group GET SET)
        (7 sysServices INTEGER op_system_group GET)
        (8 sysORLastChange TIMETICKS op_system_group GET)
        (9 sysORTable
          (1 sysOREntry : INTEGER op_or_table
            (1 sysORIndex INTEGER)
            (2 sysORID OID GET)
            (3 sysORDescr OCTETSTRING GET)
            (4 sysORUpTime TIMETICKS GET)
        ))
      )
    )
  )
)
```

## SEE ALSO

[bsnmpd(1)](/bsnmpd/1.md)

## AUTHORS

Hartmut Brandt ⟨harti@FreeBSD.org⟩