[SNMP4J] Cannot change the snmp password remotely

[Vilagut Abad, Roger]

Hello,

In order to remotely change the authentication password of a user I do the following steps:


1.       Get the usmUsrSpinLock.0 and save in sValue

2.       I obtain the old key of the user whose password I want to change as follows:
byte[] oldKey = snmp.getUSM().getUser(engineId, new OctetString(user)).getUsmUser().getAuthenticationPassphrase();

3.       Then I generate the new key as follows:

byte[] newKey = SecurityProtocols.getInstance().passwordToKey(AuthMD5.ID, new OctetString(newPassword), engineId.toByteArray());

4.       Then I generate the key change value as follows:

byte[] keyChange = new AuthMD5().changeDelta(oldKey, newKey, random.getBytes());

5.       And finally I do a SET to the usmUserTable:

SET(usmUserSpinLock.0=sValue, usmUserAuthKeyChange=keyChange, usmUserPublic=random)

When I read the usmUserTable MIB table after the SET I can see the random value in the usmUserPublic column, however when I do a request using the new password the agent responds that the password is not correct.

Am I missing something in the password change procedure? I have tried to follow the procedure described in RFC 3414 (KeyChange).

Best regards,
Roger Vilagut Abad

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