SNMPv3 Diffie-hellman Dispatching message canceled

SNMP4J
1

Hello!

I’m trying to create an SNMP listener that will simulate a cable modem and handle the SNMPv3 diffie-hellman exchange. I have a separate software that is sending the snmpv3 request, that I’ve tested against a physical cable modem and that seems to work, however when I send the request to my listener it seems to not enter my processPDU method and instead returns the OIDs the software is requesting with a null value.

This is what I have for my listener + the beginning of my processPdu

public synchronized void listen(TransportIpAddress address, int numberOfDispatcher) throws IOException {

AbstractTransportMapping transport;
if (threadPool != null) {
Log.info(“Threadpool for listener is already active”);
return;
}

if (address instanceof TcpAddress) {
transport = new DefaultTcpTransportMapping((TcpAddress) address);
} else {
transport = new DefaultUdpTransportMapping((UdpAddress) address);
}

OctetString dhKickstart = new OctetString(“dhKickstart”);

threadPool = ThreadPool.create(“DispatcherPool”, numberOfDispatcher);
MessageDispatcher mtDispatcher = new MultiThreadedMessageDispatcher(threadPool, new MessageDispatcherImpl());

// add all security protocols
SecurityProtocols.getInstance().addDefaultProtocols();
SecurityProtocols.getInstance().addPrivacyProtocol(new Priv3DES());
SecurityProtocols.getInstance().addAuthenticationProtocol(new AuthMD5());

// SnmpV3 Configuration
OctetString engineId = new OctetString(MPv3.createLocalEngineID());

USM usm = new USM(SecurityProtocols.getInstance(), engineId, 0);

usm.addLocalizedUser(engineId.getValue(), dhKickstart, SnmpConstants.usmNoAuthProtocol, null, SnmpConstants.usmNoPrivProtocol, null);

OctetString securityName = new OctetString(CONFIG.getSnmpUsername());

UsmUserEntry entry = usm.addLocalizedUser(engineId.getValue(), securityName, AuthMD5.ID, CONFIG.getSnmpAuthKey().getBytes(), PrivDES.ID, CONFIG.getSnmpPrivKey().getBytes());

// add message processing models
mtDispatcher.addMessageProcessingModel(new MPv1());
mtDispatcher.addMessageProcessingModel(new MPv2c());
mtDispatcher.addMessageProcessingModel(new MPv3(usm));

snmp = new Snmp(mtDispatcher, transport);
snmp.addCommandResponder(this);
snmp.listen();

Log.info("Listening on " + address);
}

public synchronized void processPdu(CommandResponderEvent cmdRespEvent) {
Log.debug(“Received PDU…”);
…
}

What I’m getting from the debug logs

2020-01-22 15:23:28 [INFO] Current working directory: /home/mhinton/git/firmwaretest
2020-01-22 15:23:29.381 main DEBUG Initialized Salt to fc7c4f16487aaced.
2020-01-22 15:23:29.432 main DEBUG Adding user dhKickstart = UsmUser[secName=dhKickstart,authProtocol=1.3.6.1.6.3.10.1.1.1,authPassphrase=null,privProtocol=1.3.6.1.6.3.10.1.2.1,privPassphrase=null,localizationEngineID=80:00:13:70:01:7f:00:01:01:cc:8a:b2:67]
2020-01-22 15:23:29.439 main DEBUG Adding user docsisManager = UsmUser[secName=docsisManager,authProtocol=1.3.6.1.6.3.10.1.1.2,authPassphrase=00B47671A32B43A7487EC540B5C3DFAF1F,privProtocol=1.3.6.1.6.3.10.1.2.2,privPassphrase=00B47671A32B43A7487EC540B5C3DFAF1F,localizationEngineID=80:00:13:70:01:7f:00:01:01:cc:8a:b2:67]
2020-01-22 15:23:29 [INFO] UsmUserEntry[userName=docsisManager,usmUser=UsmUser[secName=docsisManager,authProtocol=1.3.6.1.6.3.10.1.1.2,authPassphrase=00B47671A32B43A7487EC540B5C3DFAF1F,privProtocol=1.3.6.1.6.3.10.1.2.2,privPassphrase=00B47671A32B43A7487EC540B5C3DFAF1F,localizationEngineID=80:00:13:70:01:7f:00:01:01:cc:8a:b2:67],storageType=nonVolatile]
2020-01-22 15:23:29 [INFO] Listening on 0.0.0.0/161
2020-01-22 15:23:29 [INFO] Count
2020-01-22 15:23:29.460 DefaultUDPTransportMapping_0.0.0.0/161 DEBUG UDP receive buffer size for socket 0.0.0.0/161 is set to: 106496
2020-01-22 15:23:29.461 DefaultUDPTransportMapping_0.0.0.0/161 INFO Listening on socket 0.0.0.0/161
2020-01-22 15:23:31.648 DefaultUDPTransportMapping_0.0.0.0/161 DEBUG Received message from /172.20.4.45/40332 with length 63: 30:3d:02:01:03:30:10:02:04:14:1a:82:6f:02:02:05:c0:04:01:04:02:01:03:04:10:30:0e:04:00:02:01:00:02:01:00:04:00:04:00:04:00:30:14:04:00:04:00:a0:0e:02:04:67:bd:a6:0b:02:01:00:02:01:00:30:00
2020-01-22 15:23:31.670 DispatcherPool.0 DEBUG SNMPv3 header decoded: msgId=337281647, msgMaxSize=1472, msgFlags=04, secModel=3
2020-01-22 15:23:31.672 DispatcherPool.0 DEBUG RFC3414 §3.2.3 Unknown engine ID:
2020-01-22 15:23:31.686 DispatcherPool.0 DEBUG Adding cache entry: StateReference[msgID=337281647,pduHandle=PduHandle[1417038593],securityEngineID=,securityModel=org.snmp4j.security.USM@4e9fd3d5,securityName=,securityLevel=1,contextEngineID=,contextName=,retryMsgIDs=null]
2020-01-22 15:23:31.687 DispatcherPool.0 DEBUG Removed cache entry: StateReference[msgID=337281647,pduHandle=null,securityEngineID=,securityModel=org.snmp4j.security.USM@4e9fd3d5,securityName=,securityLevel=1,contextEngineID=,contextName=,retryMsgIDs=null]
2020-01-22 15:23:31.687 DispatcherPool.0 DEBUG RFC3414 §3.1.4.b Outgoing message is not encrypted
2020-01-22 15:23:31.692 DispatcherPool.0 DEBUG Sending message to 172.20.4.45/40332 from 0.0.0.0/161 with length 104: 30:66:02:01:03:30:11:02:04:14:1a:82:6f:02:03:00:ff:ff:04:01:00:02:01:03:04:1d:30:1b:04:0d:80:00:13:70:01:7f:00:01:01:cc:8a:b2:67:02:01:00:02:01:00:04:00:04:00:04:00:30:2f:04:0d:80:00:13:70:01:7f:00:01:01:cc:8a:b2:67:04:00:a8:1c:02:01:00:02:01:00:02:01:00:30:11:30:0f:06:0a:2b:06:01:06:03:0f:01:01:04:00:41:01:00
2020-01-22 15:23:31.693 DispatcherPool.0 DEBUG Sending packet to 172.20.4.45/40332
2020-01-22 15:23:31.694 DefaultUDPTransportMapping_0.0.0.0/161 DEBUG Received message from /172.20.4.45/40332 with length 152: 30:81:95:02:01:03:30:10:02:04:14:1a:82:6e:02:02:05:c0:04:01:04:02:01:03:04:28:30:26:04:0d:80:00:13:70:01:7f:00:01:01:cc:8a:b2:67:02:01:00:02:01:00:04:0b:64:68:4b:69:63:6b:73:74:61:72:74:04:00:04:00:30:54:04:0d:80:00:13:70:01:7f:00:01:01:cc:8a:b2:67:04:00:a0:41:02:04:67:bd:a6:0a:02:01:00:02:01:00:30:33:30:0f:06:0b:2b:06:01:03:65:01:02:01:01:02:01:05:00:30:0f:06:0b:2b:06:01:03:65:01:02:01:01:03:01:05:00:30:0f:06:0b:2b:06:01:03:65:01:02:01:01:04:01:05:00
2020-01-22 15:23:31.694 DispatcherPool.1 DEBUG SNMPv3 header decoded: msgId=337281646, msgMaxSize=1472, msgFlags=04, secModel=3
2020-01-22 15:23:31.705 DispatcherPool.1 DEBUG getUser(engineID=80:00:13:70:01:7f:00:01:01:cc:8a:b2:67, securityName=dhKickstart)
2020-01-22 15:23:31.707 DispatcherPool.1 DEBUG RFC3412 §7.2.10 - Received PDU is NOT a response or internal class message → unchanged PduHandle = PduHandle[1740482058]
2020-01-22 15:23:31.707 DispatcherPool.1 DEBUG Adding cache entry: StateReference[msgID=337281646,pduHandle=PduHandle[1740482058],securityEngineID=80:00:13:70:01:7f:00:01:01:cc:8a:b2:67,securityModel=org.snmp4j.security.USM@4e9fd3d5,securityName=dhKickstart,securityLevel=1,contextEngineID=80:00:13:70:01:7f:00:01:01:cc:8a:b2:67,contextName=,retryMsgIDs=null]
2020-01-22 15:23:31.737 DispatcherPool.0 INFO Dispatching message canceled due to security issue: statusInfo=1.3.6.1.6.3.15.1.1.4.0 = 0, status=1410,tmStateReference=TransportStateReference[transport=org.snmp4j.transport.DefaultUdpTransportMapping@f713686, address=0.0.0.0/161, securityName=null, requestedSecurityLevel=undefined, transportSecurityLevel=undefined, sameSecurity=false, sessionID=java.net.DatagramSocket@7a830a79, certifiedIdentity=null]
2020-01-22 15:23:31.739 DispatcherPool.1 DEBUG Fire process PDU event: CommandResponderEvent[securityModel=3, securityLevel=1, maxSizeResponsePDU=1365, pduHandle=PduHandle[1740482058], stateReference=StateReference[msgID=337281646,pduHandle=null,securityEngineID=80:00:13:70:01:7f:00:01:01:cc:8a:b2:67,securityModel=org.snmp4j.security.USM@4e9fd3d5,securityName=dhKickstart,securityLevel=1,contextEngineID=80:00:13:70:01:7f:00:01:01:cc:8a:b2:67,contextName=,retryMsgIDs=null], pdu=GET[{contextEngineID=80:00:13:70:01:7f:00:01:01:cc:8a:b2:67, contextName=}, requestID=1740482058, errorStatus=0, errorIndex=0, VBS[1.3.6.1.3.101.1.2.1.1.2.1 = Null; 1.3.6.1.3.101.1.2.1.1.3.1 = Null; 1.3.6.1.3.101.1.2.1.1.4.1 = Null]], messageProcessingModel=3, securityName=dhKickstart, processed=false, peerAddress=172.20.4.45/40332, transportMapping=org.snmp4j.transport.DefaultUdpTransportMapping@f713686, tmStateReference=TransportStateReference[transport=org.snmp4j.transport.DefaultUdpTransportMapping@f713686, address=0.0.0.0/161, securityName=null, requestedSecurityLevel=undefined, transportSecurityLevel=undefined, sameSecurity=false, sessionID=java.net.DatagramSocket@7a830a79, certifiedIdentity=null]]
2020-01-22 15:23:31.740 DispatcherPool.1 DEBUG Removed cache entry: StateReference[msgID=337281646,pduHandle=null,securityEngineID=80:00:13:70:01:7f:00:01:01:cc:8a:b2:67,securityModel=org.snmp4j.security.USM@4e9fd3d5,securityName=dhKickstart,securityLevel=1,contextEngineID=80:00:13:70:01:7f:00:01:01:cc:8a:b2:67,contextName=,retryMsgIDs=null]
2020-01-22 15:23:31.740 DispatcherPool.1 DEBUG RFC3414 §3.1.4.b Outgoing message is not encrypted
2020-01-22 15:23:31.740 DispatcherPool.1 DEBUG Sending message to 172.20.4.45/40332 from 0.0.0.0/161 with length 153: 30:81:96:02:01:03:30:11:02:04:14:1a:82:6e:02:03:00:ff:ff:04:01:00:02:01:03:04:28:30:26:04:0d:80:00:13:70:01:7f:00:01:01:cc:8a:b2:67:02:01:00:02:01:00:04:0b:64:68:4b:69:63:6b:73:74:61:72:74:04:00:04:00:30:54:04:0d:80:00:13:70:01:7f:00:01:01:cc:8a:b2:67:04:00:a2:41:02:04:67:bd:a6:0a:02:01:00:02:01:00:30:33:30:0f:06:0b:2b:06:01:03:65:01:02:01:01:02:01:05:00:30:0f:06:0b:2b:06:01:03:65:01:02:01:01:03:01:05:00:30:0f:06:0b:2b:06:01:03:65:01:02:01:01:04:01:05:00
2020-01-22 15:23:31.740 DispatcherPool.1 DEBUG Sending packet to 172.20.4.45/40332

The error I’m getting on my software doesn’t seem to get the docsisManager from the dhKickstart.
[ERR] (/device/snmp/get) Could not find user docsisManager while dhKickstarting the device 10.144.0.26

Any insight into what I might be missing would be appreciated. Or I could provide a tcpdump of the exchange too. Thanks!

2

To support the Diffie-Hellmann kick start process you need to implement the corresponding MIB (and other MIBs). I doubt, that you will get this running in less than six months if you do not use SNMP4J-Agent for this.

The AgentConfigManager class implements all necessary MIBs and agent functions needed for that.

Implementing an agent with Diffie-Hellmann key exchange support from scratch is a task that could take years until it runs securely and without major errors (and all the SNMPv3 security functions and MIBs needed for that).

3

Fair enough. We had this SNMP listener to handle SNMPv1 and SNMPv2 traffic already so I thought it would be possible to extend it to SNMPv3. I’ll start looking into the SNMP4J-Agent. Thanks!

4

Hi Frank,

I looked into the SampleAgent, and the AgentConfigManager. I’m able to get an snmp listener up and running, but I have a couple of questions on how I can modify it to handle what I need to do.

I’ve provided the AgentConfigManager the diffieHellmanKickstartParameters, but when attempting to access the usmDHKickstartTable, the response I get back is noSuchInstance for those OIDs. Do I need to create the MIB table for the kickstart table manually?

data: get-response (2)
            get-response
                request-id: 1740482203
                error-status: noError (0)
                error-index: 0
                variable-bindings: 3 items
                    1.3.6.1.3.101.1.2.1.1.2.1: noSuchInstance
                        Object Name: 1.3.6.1.3.101.1.2.1.1.2.1 (iso.3.6.1.3.101.1.2.1.1.2.1)
                        noSuchInstance
                            [Expert Info (Note/Response): noSuchInstance]
                    1.3.6.1.3.101.1.2.1.1.3.1: noSuchInstance
                        Object Name: 1.3.6.1.3.101.1.2.1.1.3.1 (iso.3.6.1.3.101.1.2.1.1.3.1)
                        noSuchInstance
                            [Expert Info (Note/Response): noSuchInstance]
                    1.3.6.1.3.101.1.2.1.1.4.1: noSuchInstance
                        Object Name: 1.3.6.1.3.101.1.2.1.1.4.1 (iso.3.6.1.3.101.1.2.1.1.4.1)
                        noSuchInstance
                            [Expert Info (Note/Response): noSuchInstance]

I saw in the sample agent the method for registering MIBs and I’ve tried the provided code to add a scalar

void registerMIBs() {
if (modules == null) {
modules = new Modules(getFactory());
modules.getSnmp4jDemoMib().getSnmp4jDemoEntry().addMOTableRowListener(new DemoTableRowListener());
((TimeStamp) modules.getSnmp4jDemoMib().getSnmp4jDemoEntry()
.getColumn(Snmp4jDemoMib.idxSnmp4jDemoEntryCol4)).setSysUpTime(agent.getSysUpTime());
}
try {
modules.registerMOs(server, null);
MOScalar myScalar = new MOScalar(new OID(“1.2.3.5.6.0”), MOAccessImpl.ACCESS_READ_CREATE,
new OctetString(“myText”));
server.register(myScalar, null);
…

And the results come back as noSuchObject when trying to grab that OID, vs one that seems already provided.

Frame 2: 84 bytes on wire (672 bits), 84 bytes captured (672 bits)
Linux cooked capture
Internet Protocol Version 4, Src: 10.144.0.26, Dst: 172.20.4.45
User Datagram Protocol, Src Port: 161, Dst Port: 40537
Simple Network Management Protocol
version: v2c (1)
community: public
data: get-response (2)
get-response
request-id: 1740482228
error-status: noError (0)
error-index: 0
variable-bindings: 1 item
1.2.3.5.6.0: noSuchObject
Object Name: 1.2.3.5.6.0 (iso.2.3.5.6.0)
noSuchObject
[Expert Info (Note/Response): noSuchObject]

Working one

Frame 2: 94 bytes on wire (752 bits), 94 bytes captured (752 bits)
Linux cooked capture
Internet Protocol Version 4, Src: 10.144.0.26, Dst: 172.20.4.45
User Datagram Protocol, Src Port: 161, Dst Port: 42807
Simple Network Management Protocol
version: v2c (1)
community: public
data: get-response (2)
get-response
request-id: 1740482229
error-status: noError (0)
error-index: 0
variable-bindings: 1 item
1.3.6.1.2.1.198.2.2.1.3.1.5.2: 3
Object Name: 1.3.6.1.2.1.198.2.2.1.3.1.5.2 (iso.3.6.1.2.1.198.2.2.1.3.1.5.2)
Value (Integer32): 3

Am I missing something to registering your own OIDs? Thanks!

Regards,
Matt

5

Hi Matt,

Those objects of the usmDHKickstartTable are not used/published by AgentConfigManager by default. For DH kickstart those values are not required. The current implementation uses out-of-band property file exchange instead.

Nevertheless, future versions of SNMP4J-Agent will add support for that table.

Best regards
Frank