Cable Modems sold in retail market are compliant to DOCSIS 3.0 (3.1/3.0 with newer modems) standards. This means all the modems have an in-built SNMP agent which can be queried through a WAN or LAN side. While a user cannot just query through WAN side as it will be done by ISP from the network side. But DOCSIS 3.0 OSSI Specs require the modem to support SNMP Agent via LAN (or the spec calls CMCI interface) as well.

Almost all the Cable modems/Modem Routers, support SNMP Agent listening at 192.168.100.1. This only works if your modem is offline and not connected to ISPs network (this is done for security purposes).

You can download CLI SNMPget or SNMPwalk from the snmpsoft’s website and run the queries on your modem.

Link to download SNMPwalk is here:

Command Syntax is as below:

SnmpWalk.exe [-q] -r:host [-p:port] [-t:timeout] [-v:version] [-c:community]
        [-ei:engine_id] [-sn:sec_name] [-ap:auth_proto] [-aw:auth_passwd]
        [-pp:priv_proto] [-pw:priv_passwd] [-ce:cont_engine] [-cn:cont_name]
        [-os:start_oid] [-op:stop_oid] [-csv]

   -q               Quiet mode (suppress header; print variable values only).
   -r:host          Name or network address (IPv4/IPv6) of remote host.
   -p:port          SNMP port number on remote host. Default: 161
   -t:timeout       SNMP timeout in seconds (1-600). Default: 5
   -v:version       SNMP version. Supported version: 1, 2c or 3. Default: 1
   -c:community     SNMP community string for SNMP v1/v2c. Default: public
   -ei:engine_id    Engine ID. Format: hexadecimal string. (SNMPv3).
   -sn:sec_name     SNMP security name for SNMPv3.
   -ap:auth_proto   Authentication protocol. Supported: MD5, SHA (SNMPv3).
   -aw:auth_passwd  Authentication password (SNMPv3).
   -pp:priv_proto   Privacy protocol. Supported: DES, IDEA, AES128, AES192,
                    AES256, 3DES (SNMPv3).
   -pw:priv_passwd  Privacy password (SNMPv3).
   -cn:cont_name    Context name. (SNMPv3)
   -ce:cont_engine  Context engine. Format: hexadecimal string. (SNMPv3)
   -os:start_oid    Object ID (OID) of first SNMP variable to walk. Default:.1
   -op:stop_oid     Object ID (OID) of last SNMP variable to walk.
                    Default: walk to the very last variable.
   -csv             Output in CSV (Comma Separated Values) format.

An example command to find Cable Modem's System Descriptor values and more is:

SnmpWalk.exe -r:192.168.100.1 -t:10 -os:.1.3.6.1.2.1.1