Jan Henning Thorsen


DOCSIS::ConfigFile - Decodes and encodes DOCSIS config files




DOCSIS::ConfigFile is a class which provides functionality to decode and encode DOCSIS (Data over Cable Service Interface Specifications) config files.

This module is used as a layer between any human readable data and the binary structure.

The files are usually served using a TFTP server, after a cable modem or MTA (Multimedia Terminal Adapter) has recevied an IP address from a DHCP server. These files are binary encode using a variety of functions, but all the data in the file are constructed by TLVs (type-length-value) blocks. These can be nested and concatenated.

See "CONFIGURATION TREE" in DOCSIS::ConfigFile::Syminfo for full set of possible parameters. Create an issue if a parameter is missing or invalid.


  use DOCSIS::ConfigFile qw(encode_docsis decode_docsis);

  $data = decode_docsis $bytes;

  $bytes = encode_docsis(
               GlobalPrivacyEnable => 1,
               MaxCPE              => 2,
               NetworkAccess       => 1,
               BaselinePrivacy => {
                 AuthTimeout       => 10,
                 ReAuthTimeout     => 10,
                 AuthGraceTime     => 600,
                 OperTimeout       => 1,
                 ReKeyTimeout      => 1,
                 TEKGraceTime      => 600,
                 AuthRejectTimeout => 60,
                 SAMapWaitTimeout  => 1,
                 SAMapMaxRetries   => 4
               SnmpMibObject => [
                 {oid => "",    INTEGER => 1},
                 {oid => "", STRING  => "bootfile.bin"}
               VendorSpecific => {
                 id => "0x0011ee",
                 options => [30 => "0xff", 31 => "0x00", 32 => "0x28"]

See also "CONFIGURATION TREE" in DOCSIS::ConfigFile::Syminfo.


You can install the SNMP.pm module to translate between SNMP OID formats. With the module installed, you can define the SnmpMibObject like the example below, instead of using numeric OIDs:

      SnmpMibObject => [
        {oid => "docsDevNmAccessIp.1",     IPADDRESS => ""},
        {oid => "docsDevNmAccessIpMask.1", IPADDRESS => ""},



  $data = decode_docsis($byte_string);
  $data = decode_docsis(\$path_to_file);

Used to decode a DOCSIS config file into a data structure. The output $data can be used as input to "encode_docsis". Note: $data will only contain array-refs if the DOCSIS parameter occur more than once.


  $byte_string = encode_docsis(\%data, \%args);

Used to encode a data structure into a DOCSIS config file. Each of the keys in $data can either hold a hash- or array-ref. An array-ref is used if the same DOCSIS parameter occur multiple times. These two formats will result in the same $byte_string:

  # Only one SnmpMibObject
    SnmpMibObject => {
      oid => "", STRING => "bootfile.bin"

  # Allow one or more SnmpMibObjects
    SnmpMibObject => [
      {oid => "", STRING => "bootfile.bin"}

Possible %args:

  • mta_algorithm

    This argument is required when encoding MTA config files. Can be set to either empty string, "sha1" or "md5".

  • shared_secret

    This argument is optional, but will be used as the shared secret used to increase security between the cable modem and CMTS.


Copyright (C) 2014, Jan Henning Thorsen

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.


Jan Henning Thorsen - jhthorsen@cpan.org