Alpha Technologies AlphaNet DSM Series DOCSIS - Manual (Page 21)

21 745-814-B0-001, Rev. A
3.0 Network Configuration, continued
3.5 Security in Dual IP Mode
In Dual IP Mode additional SNMP security is required because data is exposed on the CPE
network, which is more vulnerable to packet sniffing and community string deciphering than
on the secure cable modem network. For an explanation of Dual IP Mode, see Section 2.2 .
For an explanation of the Alpha MIB, see Section 6.2 .
There are two methods of providing SNMP Security in Dual-IP Mode: the Secure Access List,
and the Key-Match.
Method 1: Security Using the Secure Access Table
The Secure Access List method limits remote SNMP access to four IP addresses. Only those
IP addresses listed in the SNMP Access Table are able to read or write to the Alpha MIB
parameters from the public (CPE) network. Set the IP addresses through the following Alpha
MIB parameter:
The entries in the SNMP Access Table can be set through the local port (see Section 4.0 ), the
DSM Setup File (see Section 3.4 ), or remotely using SNMP.
SNMP Parameter Local Port Parameter Description Type Value
atiMgmtSnmpAccessTable
1.3.6.1.4.1.926.1.3.1.2
[Text] SNMP ACCESS LIST Restricted DSM
SNMP Access”
IP address 0.0.0.0 (Default)
NOTE:
The XP-DSM transponder variables will still be accessible through the private modem
management network using the community strings without requiring additional security.
If the entries in the SNMP Access Table are set remotely using SNMP through the cable modem’s IP address,
then the SNMP community strings will have to be used. However, if they are set remotely through the public
(CPE) IP address the data access key, explained below, must be used to gain access.
Method 2: Security Using the Data Access Key
SNMP Parameter Local Port Parameter Description Type Value
atiMgmtSnmpAlphaSetAccess
1.3.6.1.4.1.926.1.3.1.3.3.0
[Discretes] ALPHA SNMP SETS Set to Access Key Read/Write
Octet String
Set to match the value of
atiMgmtSnmpAlphaSetKey
atiMgmtSnmpAlphaSetKey
1.3.6.1.4.1.926.1.3.1.3.4.0
[Text] ALPHA SNMP SETS Data Access Key Read/Write
Octet String
CIBSET (default)
ALPHA SNMP SETS
1.3.6.1.4.1.926.1.2.1.1.1.5
[Discretes] ALPHA SNMP SETS OID of Dicrete Table
Value
Read/Write
Integer
0 = Disabled
1 = Enabled
If in Dual IP Mode and not using the Secure Access List Method (above),
atiMgmtSnmpAlphaSetAccess is the only SNMP parameter with SNMP-Write access on
the CPE network by default. When this parameter is set to the value of the parameter
atiMgmtSnmpAlphaSetKey, the data access key, SNMP write access is granted to all
parameters in the Alpha MIB tree. When this access is granted, the value of ALPHA SNMP
SETS in the discretes table automatically switches to ‘1’, enabled. After the operator is
finished setting SNMP variables, SNMP-write access can be disabled by either manually
setting this value to ‘0’ or by setting atiMgmtSnmpAlphaSetAccess to any value other than the
data access key.
The data access key can be set by changing the value of atiMgmtSnmpAlphaSetKey through
the local port, through SNMP using the modem’s IP address, or through the CPE IP address
once access has been granted and the value of ALPHA SNMP SETS in the discretes table is
‘1’, enabled.