What is the proper syntax, or address/mask combo for the SNMP Transport Address fields? I'm trying to secure modems on my network by altering the SNMP community strings. I see that in the DOCSIS3 modems there are fields to control the transport address. One Fields is asking for "address" indicated the response should be "address/port", the other "address mask" is requesting similar response.
should the "Transport Address" field look something like this:
172.16.100.10/161 (where 161 is UDP/TCP 161)
or
172.16.100.10/32 (where 32 is netmask)
IF so... what does the "Transport Address Mask" look like?
255.255.254.0/161 (actual host subnet mask and TCP/UDP port)?
or something different?
I've tried a few combo's but there is a 20 min delay, beyond the difficulty of editing, and staging the cable.cm file.
Thanks
-Rich
not 100% sure but I think the relevant RFC is RFC 3419 https://tools.ietf.org/html/rfc3419
TransportAddressIPv4 ::= TEXTUAL-CONVENTION
DISPLAY-HINT "1d.1d.1d.1d:2d"
STATUS current
DESCRIPTION
"Represents a transport address consisting of an IPv4
address and a port number (as used for example by UDP,
TCP and SCTP):
octets contents encoding
1-4 IPv4 address network-byte order
5-6 port number network-byte order
This textual convention SHOULD NOT be used directly in object
definitions since it restricts addresses to a specific format.
However, if it is used, it MAY be used either on its own or
in conjunction with TransportAddressType or TransportDomain
as a pair."
SYNTAX OCTET STRING (SIZE (6))
note the encoding is octet string
int the examples they list the following relevant examples
5. Examples
This section shows some examples how transport addresses are encoded
and rendered using some of the transport address definitions.
Description: Unspecified IPv4 address on port 80.
Encoding (hex): 000000000050
Display: 0.0.0.0:80
Description: Global IPv4 address on port 80.
Encoding (hex): 86A922010050
Display: 134.169.34.1:80
so per your example it should be
Description: Global IPv4 address on port 161.
Encoding (hex): AC10640A00A1
Display: 172.16.100.10:161
used calc app to convert to hex
172=AC
16=10
100=64
10=0A
161=00A1