Managing Windows Networks Using Script -- Part 8: Handling Remote

This updated guide examines Managing Windows Networks Using Script -- Part 8: Handling Remote and organizes the essential facts, background, and practical takeaways in clear American English.

Mitch Tulloch

In Part 7, we started troubleshooting the error that occurred when trying to remotely change the IP address on an XP computer using the ChangeIPAddress.vbs script that was previously developed. The error is:

SWbemObjectEx: The remote procedure call failed

In the previous section, we mentioned that we have contacted some reputable experts in handling this error, and the best answer to get it is a hotfix that can corrupt WMI functionality and results. The script is working but with it there is an error. A reader contacted me with the comment below: In my opinion this is not a bug in the hotfix. Notice that you are changing the IP address of XP2. The remote call procedure failed because it lost the connection with XP2 on the original address (172.16.11.43). It then depends on the time (about 1 minute) to search for XP2 new IP address (172.16.11.65) before removing the old address. Imagine you only infiltrated a server like an administrator and changed the server's IP address. Will you lose connection? It will hang for a moment. But changing the default port on the server will not disconnect an existing connection (assuming you do this from the same subnet). If you try to change the default port setting from a remote location, you must be delayed . So how can we check this explanation? Use Network Monitor 3.0 Microsoft recently released a new version of Network Monitor, which is part of Microsoft Systems Management Server. Network Monitor 3.0 has several improvements over the previous version, namely:

• Improved user interface displays frames when they are active in real time.
• Multiple simultaneous capture sessions and simultaneous capture on multiple network adapters.
• The ability to display network 'conversations', ie specific session protocols.
• Support for Vista, Windows XP and Windows Server 2003 (both 32 bit and 64 bit).
• The new filter panel allows you to use specified filters.

We are using NM3 to catch traces from the computer on which the ChangeIPAddress.vbs script is running. Here is the setup section to check: Administrator machine workstation Name: test124.test.com IP address: 172.16.11.124 (static) Destination machine Name: test125.test.com IP address: 172.16.11.125 (static) Domain controller Name: dc181.test.com IP address: 172.16.11.181 However, before running ChangeIPAddress.vbs on test124 to change the IP address of test125, look at NM3 a bit. When you launch NM3, it will have the interface as shown in Figure 1:

Figure 1: Network Monitor 3.0 window when opened

Before proceeding, select the Enable Conversations checkbox so that we can see the type of session protocol that appears during the trace. Now click on the New Capture tab. This allows you to open a new tab called Capture1 that can be used to create network traces.

Figure 2: Open a new capture tab

Please check NM3 in a simple way. Click the Play button to start a capture, then from computer test124 open a command window and enter ping 172.16.11.125 which means we are pinging test125 to test124. The result is shown in Figure 3 below:

Figure 3: Analysis of ping 172.16.11.125

This is what we expect: two ARP packets (an ARP request followed by an ARP response) and a series of ICMP packets (Echo Request messages are given after Echo Reply messages). If you know the basic TCP / IP network connection, this is completely understandable. Look at the 'conversation' situation that happened in Figure 4. Open the My Traffic button to display it:

Figure 4: 'Conversations'

Note that two "conversations" have appeared: ARP and IPv4 (ICMP). Now select the ARP Request package and look inside it (Figure 5):

Figure 5: Examining a package

We have been introduced briefly about NM3, now use it to handle some errors. Trace times We started by restarting both workstations and clearing the cache (ARP, NDS,.), then opening the command prompt on computer test124, typing ChangeIPAddress.vbs 172.16.11.144 to change the IP address. of the test125 computer from 172.16.11.125 to 172.16.11.144. Figure 6 below is the results obtained:

Figure 6: Results obtained when running ChangeIPAddress.vbs 172.16.11.144

Figure 6 is an overview of what happened. Retained the last 90 seconds and had 274 frames kept. The error message appears around frame 241 and the command window returns at frame 274. There is a lot of traffic that we can analyze! Look at Figure 6 above, we can start analyzing it:

• 3-4 frames show the name TEST125 existing under the IP address 172.16.11.125 using DNS.
• Frames 5-6 show the existing 172.16.11.125 IP address within the MAC address using ARP.
• Frames 7-9 show the 'handshake' procedure of TCP (SYN, SYN / ACK, ACK) appearing between test124 and test125 computers.
• 10-11 frames represent existing RPC constraints established between two computers.
• Frames 12-13 represent the existing DCOM used on RCP (WMI uses DCOM to 'shake hands' remote calls).

We cannot see all 274 frames in the drawing, so we copied the information about all frames into a text file. You can click here to see the information about all frames when running ChangeIPAddress.vbs. When troubleshooting common sense you have to start with what you know rather than what you don't understand. With that in mind, we understand that the other script (ChangeGateway.vbs) we developed in the previous article worked without generating any error messages. So before considering carefully in the file ChangeIPAddress.txt, restart your workstations and perform another capture, which will show the results of running ChangeGateway.vbs command 172.16.11.2 1 on test124 to replace Change the default port of test125 from 172.16.11.1 to 172.16.11.2 (specify the parameter measured by 1). This is what the second capture shows (Figure 7):

Figure 7: Results running ChangeGateway.vbs 172.16.11.2 1

Now there are only 217 frames to analyze (!) And you can go here to see the summary of all the frames. Analysis of capture for ChangeGateway.vbs Now let's try and analyze this second capture (working without generating errors) by dividing the summary of the frames into sections, which is one of them:

1 0.000000 NetmonFilter NetmonFilter: Updated Capture Filter: None 2 0.000000 NetworkInfo NetworkInfo: Network info for TEST124, Network Adapter Count = 1

Only NM3 header - ignored

3 0.000000 {DNS: 3, UDP: 2, IPv4: 1} 172.16.11.124 dc181.test.local DNS DNS: QueryId = 0x4275, QUERY (Standard query), Query for 124.11.16.172.in-addr.arpa of type SOA on class Internet 4 1.281250 {ARP: 4} 172.16.11.181 172.16.11.1 ARP ARP: Request, 172.16.11.181 asks for 172.16.11.1 5 1.890625 {DNS: 6, UDP: 5, IPv4: 1} 172.16.11.124 dc181.test.local DNS DNS: QueryId = 0xEB6E, QUERY (Standard query), Query for test125.test.local of type Host Addr on Internet class 6 1.890625 {DNS: 6, UDP: 5, IPv4: 1} dc181.test.local 172.16.11.124 DNS DNS: QueryId = 0xEB6E, QUERY (Standard query), Response - Success 7 1.906250 {ARP: 7} 172.16.11.124 172.16.11.125 ARP ARP: Request, 172.16.11.124 asks for 172.16.11.125 8 1.906250 {ARP: 7} 172.16.11.125 172.16.11.124 ARP ARP: Response, 172.16.11.125 at 00-11-D8-E3-EC-84

Name and address (DNS and ARP)

9 1.906250 {TCP: 9, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. S., SrcPort = 1069, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 1441244938, Ack = 0, Win = 65535 (scale factor 0) = 65535 10.906250 {TCP: 9, IPv4: 8} test125.test.local 172.16.11.124 TCP TCP: Flags =. S. A., SrcPort = DCE endpoint resolution (135), DstPort = 1069, Len = 0, Seq = 871910569, Ack = 1441244939, Win = 65535 (scale factor 0) = 65535 11 1.906250 {TCP: 9, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. A., SrcPort = 1069, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 1441244939, Ack = 871910570, Win = 65535 (scale factor 0) = 65535

Test124 established a TVP connection with test125.

12 1.906250 {MSRPC: 10, TCP: 9, IPv4: 8} 172.16.11.124 test125.test.local MSRPC MSRPC: c / o Bind: UUID {99FCFEC4-5260-101B-BBCB-00AA0021347A} DCOM-IObjectExporter Call = 0x1 Assoc Grp = 0x0 Xmit = 0x16D0 Recv = 0x16D0 13 1.906250 {MSRPC: 10, TCP: 9, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC: c / o Ack: Call = 0x1 Assoc Grp = 0x32E9 Xmit = 0x16D0 Recv = 0x16D0 14 1.906250 {MSRPC: 10, TCP: 9, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 15 1.906250 {MSRPC: 10, TCP: 9, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM

Test124 establishes an RCP binding with test125 and calls DCOM.

16 1.921875 {TCP: 11, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. S., SrcPort = 1070, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 3003512395, Ack = 0, Win = 65535 (scale factor 0) = 65535 17 1.921875 {TCP: 11, IPv4: 8} test125.test.local 172.16.11.124 TCP TCP: Flags =. S. A., SrcPort = DCE endpoint resolution (135), DstPort = 1070, Len = 0, Seq = 4088700167, Ack = 3003512396, Win = 65535 (scale factor 0) = 65535 18 1.921875 {TCP: 11, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. A., SrcPort = 1070, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 3003512396, Ack = 4088700168, Win = 65535 (scale factor 0) = 65535

3-way TCP handshake between two computers.

19 1.921875 {UDP: 12, IPv4: 1} 172.16.11.124 dc181.test.local KerberosV5 KerberosV5: TGS Request Realm: TEST. LOCAL Sname: RPCSS / test125.test.local 20 1.921875 {UDP: 12, IPv4: 1} dc181.test.local 172.16.11.124 KerberosV5 KerberosV5: TGS Response Cname: Administrator

Kerberos authentication

21 1.921875 {MSRPC: 13, TCP: 11, IPv4: 8} 172.16.11.124 test125.test.local MSRPC MSRPC: c / o Bind: UUID {000001A0-0000-0000-C000-000000000046} DCOM-IRemoteSCMActivator Call = 0x2 Assoc Grp = 0x32E9 Xmit = 0x16D0 Recv = 0x16D0 22 1.921875 {ARP: 14} 172.16.11.181 172.16.11.125 ARP ARP: Request, 172.16.11.181 asks for 172.16.11.125 23 1.921875 {MSRPC: 13, TCP: 11, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC: c / o Ack: Call = 0x2 Assoc Grp = 0x32E9 Xmit = 0x16D0 Recv = 0x16D0 24 1.921875 {MSRPC: 13, TCP: 11, IPv4: 8} 172.16.11.124 test125.test.local MSRPC MSRPC: Alter Cont: UUID {000001A0-0000-0000-C000-000000000046} DCOM-IRemoteSCMActivator Call = 0x2 25 1.921875 {MSRPC: 13, TCP: 11, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC: Alter Cont Resp: Call = 0x2 Assoc Grp = 0x32E9 Xmit = 0x16D0 Recv = 0x16D0 26 1.921875 {MSRPC: 13, TCP: 11, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 27 1.937500 {MSRPC: 13, TCP: 11, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM

Many RPC and DCOM. We think that 'Alter Cont' indicates that interstitial content is being used, but in fact it is not guaranteed. It should have been OK when the script worked without generating any errors.

28 1.937500 {TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. S., SrcPort = 1072, DstPort = 1117, Len = 0, Seq = 3011418470, Ack = 0, Win = 65535 (scale factor 0) = 65535 29 1.937500 {TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 TCP TCP: Flags =. S. A., SrcPort = 1117, DstPort = 1072, Len = 0, Seq = 554832695, Ack = 3011418471, Win = 65535 (scale factor 0) = 65535 30 1.937500 {TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. A., SrcPort = 1072, DstPort = 1117, Len = 0, Seq = 3011418471, Ack = 554832696, Win = 65535 (scale factor 0) = 65535

Another TCP handshake

31 1.937500 {UDP: 16, IPv4: 1} 172.16.11.124 dc181.test.local KerberosV5 KerberosV5: TGS Request Realm: TEST. LOCAL Sname: TEST125 $ 32 1.937500 {UDP: 16, IPv4: 1} dc181.test.local 172.16.11.124 KerberosV5 KerberosV5: TGS Response Cname: Administrator

Continue with Kerberos

33 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local MSRPC MSRPC: c / o Bind: UUID {00000143-0000-0000-C000-000000000046} DCOM-IRemUnknown2 Call = 0x1 Assoc Grp = 0x0 Xmit = 0x16D0 Recv = 0x16D0 34 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC: c / o Bind Ack: Call = 0x1 Assoc Grp = 0x333D Xmit = 0x16D0 Recv = 0x16D0 35 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local MSRPC MSRPC: c / o Alter Cont: UUID {00000143-0000-0000-C000-000000000046} DCOM-IRemUnknown2 Call = 0x1 36 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC Alter Cont Resp: Call = 0x1 Assoc Grp = 0x333D Xmit = 0x16D0 Recv = 0x16D0 37 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 38 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 39 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local MSRPC MSRPC: Alter Cont: UUID {D4781CD6-E5D3-44DF-AD94-930EFE48A887} WMI-IWbemLoginClientID Call = 0x2 40 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC: Alter Cont Resp: Call = 0x2 Assoc Grp = 0x333D Xmit = 0x16D0 Recv = 0x16D0 41 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 42 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 43 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local MSRPC MSRPC: Alter Cont: UUID {F309AD18-D86A-11D0-A075-00C04FB68820} WMI-IWbemLevel1Login Call = 0x3 44 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC: Alter Cont Resp: Call = 0x3 Assoc Grp = 0x333D Xmit = 0x16D0 Recv = 0x16D0 45 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 46 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 47 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 48 1.937500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 49 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local MSRPC MSRPC: Alter Cont: UUID {9556DC99-828C-11CF-A37E-00AA003240C7} WMI-IWbemServices Call = 0x5 50 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC: Alter Cont Resp: Call = 0x5 Assoc Grp = 0x333D Xmit = 0x16D0 Recv = 0x16D0 51 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 52 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 53 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 54 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 55 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local MSRPC MSRPC: Alter Cont: UUID {1C1C45EE-4395-11D2-B60B-00104B703EFD} WMI-IWbemFetchSmartEnum Call = 0x7 56 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC: Alter Cont Resp: Call = 0x7 Assoc Grp = 0x333D Xmit = 0x16D0 Recv = 0x16D0 57 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 58 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 59 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local MSRPC MSRPC: Alter Cont: UUID {423EC01E-2E35-11D2-B604-00104B703EFD} WMI-IWbemWCOSmartEnum Call = 0x8 60 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC Alter Cont Resp: Call = 0x8 Assoc Grp = 0x333D Xmit = 0x16D0 Recv = 0x16D0 61 1.953125 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 62 2.015625 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM

There are many RPC / DCOM here. It may seem mysterious but if you look closely you will see some of the existing WMI such as WMI-IWbemLoginClientID, WMI-IWbemLevel1Login, WMI-IWbemServices, WMI-IWbemFetchSmartEnum,. Searching on MSDN shows us more information about what happens. For example, this page tells us that 'IwbemServices interface is used for clients and providers to be able to access WMI services' so it is like existing WMI interfaces. call on the remote computer (using DCOM) by the host computer running the script from it. Some interfaces are not really confusing for readers. The most confusing thing for the first reader is that the TCP clusters with RPC 'Continued Response' packets seem to indicate that connections made earlier are being used for many other purposes. We will skip some frames in this next section.

63 2.015625 {TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 TCP TCP: [Continuation to # 62] Flags =. A., SrcPort = 1117, DstPort = 1072, Len = 1460, Seq = 554835972 - 554837432, Ack = 3011421991, Win = 65061 (scale factor 0) = 65061 64 2.015625 {TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. A., SrcPort = 1072, DstPort = 1117, Len = 0, Seq = 3011421991, Ack = 554837432, Win = 65535 (scale factor 0) = 65535 65 2.015625 {TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 TCP TCP: [Continuation to # 62] Flags =. A., SrcPort = 1117, DstPort = 1072, Len = 1460, Seq = 554837432 - 554838892, Ack = 3011421991, Win = 65061 (scale factor 0) = 65061 66 2.015625 {TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. A., SrcPort = 1072, DstPort = 1117, Len = 0, Seq = 3011421991, Ack = 554838892, Win = 65535 (scale factor 0) = 65535 67 2.015625 {TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 TCP TCP: [Continuation to # 62] Flags =. PA., SrcPort = 1117, DstPort = 1072, Len = 1449, Seq = 554838892 - 554840341, Ack = 3011421991, Win = 65061 (scale factor 0) = 65061 68 2.015625 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC: c / o Continued Response: WMI-IWbemWCOSmartEnum Call = 0x8 Context = 0x5 Hint = 0x198C Cancels = 0x0 . . . 155 2.031250 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 MSRPC MSRPC: c / o Continued Response: WMI-IWbemServices Call = 0x9 Context = 0x3 Hint = 0x904 Cancels = 0x0 156 2.031250 {TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 TCP TCP: [Continuation to # 155] Flags =. PA., SrcPort = 1117, DstPort = 1072, Len = 929, Seq = 554924260 - 554925189, Ack = 3011422236, Win = 64816 (scale factor 0) = 64816 157 2.031250 {TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. A., SrcPort = 1072, DstPort = 1117, Len = 0, Seq = 3011422236, Ack = 554925189, Win = 65535 (scale factor 0) = 65535 158 2.031250 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 159 2.031250 {TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: [Continuation # 158] Flags =. PA., SrcPort = 1072, DstPort = 1117, Len = 1, Seq = 3011423696 - 3011423697, Ack = 554925189, Win = 65535 (scale factor 0) = 65535 160 2.031250 {TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 TCP TCP: Flags =. A., SrcPort = 1117, DstPort = 1072, Len = 0, Seq = 554925189, Ack = 3011423697, Win = 65535 (scale factor 0) = 65535

We have a DCOM cluster followed by TCP connection endings with FIN / ACK, so it is predicted that the script might have done its job and is cleaning up.

161 2.062500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 162 2.062500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 163 2.062500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 164 2.062500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 165 2.062500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 166 2.062500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 167 2.062500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 168 2.062500 {MSRPC: 17, TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local DCOM DCOM 169 2.062500 {MSRPC: 17, TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 DCOM DCOM 170 2.078125 {TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags = F. A., SrcPort = 1072, DstPort = 1117, Len = 0, Seq = 3011424421, Ack = 554926046, Win = 64678 (scale factor 0) = 64678 171 2.078125 {TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 TCP TCP: Flags =. A., SrcPort = 1117, DstPort = 1072, Len = 0, Seq = 554926046, Ack = 3011424422, Win = 64811 (scale factor 0) = 64811 172 2.078125 {TCP: 15, IPv4: 8} test125.test.local 172.16.11.124 TCP TCP: Flags = F. A., SrcPort = 1117, DstPort = 1072, Len = 0, Seq = 554926046, Ack = 3011424422, Win = 64811 (scale factor 0) = 64811 173 2.078125 {TCP: 15, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. A., SrcPort = 1072, DstPort = 1117, Len = 0, Seq = 3011424422, Ack = 554926047, Win = 64678 (scale factor 0) = 64678 174 2.093750 {TCP: 9, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. A., SrcPort = 1069, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 1441245035, Ack = 871910766, Win = 65339 (scale factor 0) = 65339 175 2.093750 {TCP: 11, IPv4: 8} 172.16.11.124 test125.test.local TCP TCP: Flags =. A., SrcPort = 1070, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 3003514721, Ack = 4088701653, Win = 65535 (scale factor 0) = 65535 176 2.546875 {TCP: 18, IPv4: 1} 172.16.11.124 dc181.test.local TCP TCP: Flags =. S., SrcPort = 1074, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 4283854964, Ack = 0, Win = 65535 (scale factor 0) = 65535 177 2.546875 {TCP: 18, IPv4: 1} dc181.test.local 172.16.11.124 TCP TCP: Flags =. S. A., SrcPort = DCE endpoint resolution (135), DstPort = 1074, Len = 0, Seq = 2447011944, Ack = 4283854965, Win = 16384 (scale factor 0) = 16384 178 2.546875 {TCP: 18, IPv4: 1} 172.16.11.124 dc181.test.local TCP TCP: Flags =. A., SrcPort = 1074, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 4283854965, Ack = 2447011945, Win = 65535 (scale factor 0) = 65535

Here are some DNS and LDAP that appear between test124 and domain controller. It is not clear why it happened, but we will ignore some of them when they appear too much:

179 2.546875 {MSRPC: 19, TCP: 18, IPv4: 1} 172.16.11.124 dc181.test.local MSRPC MSRPC: c / o Bind: UUID {E1AF8308-5D1F-11C9-91A4-08002B14A0FA} Endpoint Mapper Call = 0x1 Assoc Grp = 0x0 Xmit = 0x16D0 Recv = 0x16D0 180 2.546875 {MSRPC: 19, TCP: 18, IPv4: 1} dc181.test.local 172.16.11.124 MSRPC MSRPC: c / o Bind Ack: Call = 0x1 Assoc Grp = 0x7DAD Xmit = 0x16D0 Recv = 0x16D0 181 2.546875 {MSRPC: 19, TCP: 18, IPv4: 1} 172.16.11.124 dc181.test.local EPM EPM: Request: ept_map: NDR, Tracking Server Service v1.0, RPC v5, 0.0.0.0:135 (0x87) [DCE endpoint resolution (135)] 182 2.546875 {MSRPC: 19, TCP: 18, IPv4: 1} dc181.test.local 172.16.11.124 EPM EPM: Response: ept_map: 0x16C9A0D6 - EP_S_NOT_REGISTERED 183 2,546875 {DNS: 21, UDP: 20, IPv4: 1} 172.16.11.124 dc181.test.local DNS DNS: QueryId = 0x896A, QUERY (Standard query), Query for _ldap._tcp. Default-First-Site._sites. dc._msdcs.test.local of type SRV on class Internet 184 2,546875 {DNS: 21, UDP: 20, IPv4: 1} dc181.test.local 172.16.11.124 DNS DNS: QueryId = 0x896A, QUERY (Standard query), Response - Success 185 2.546875 {LDAP: 23, UDP: 22, IPv4: 1} 172.16.11.124 dc181.test.local LDAP LDAP: Search Request, MessageID: 4, BaseObject: NULL, SearchScope: base Object, SearchAlias: neverDerefAliases 186 2,546875 {LDAP: 23, UDP: 22, IPv4: 1} dc181.test.local 172.16.11.124 LDAP LDAP: Search Result Entry, MessageID: 4, Status: Success . . . 212 6.546875 {DNS: 32, UDP: 5, IPv4: 1} 172.16.11.124 dc181.test.local DNS DNS: QueryId = 0x266D, QUERY (Standard query), Query for download.windowsupdate.com of the Host Addr on class Internet type 213 6.546875 {ARP: 4} 172.16.11.181 172.16.11.1 ARP ARP: Request, 172.16.11.181 asks for 172.16.11.1 214 7.546875 {DNS: 32, UDP: 5, IPv4: 1} 172.16.11.124 dc181.test.local DNS DNS: QueryId = 0x266D, QUERY (Standard query), Query for download.windowsupdate.com of the Host Addr on class Internet type 215 8.546875 {DNS: 32, UDP: 5, IPv4: 1} 172.16.11.124 dc181.test.local DNS DNS: QueryId = 0x266D, QUERY (Standard query), Query for download.windowsupdate.com of the Host Addr on class Internet type 216 9.281250 {ARP: 4} 172.16.11.181 172.16.11.1 ARP ARP: Request, 172.16.11.181 asks for 172.16.11.1

At this point, the script is ready to finish so we have finished capturing. Analysis of Capture for ChangeIPAddress.vbs Now we have a little idea of what a capture of the successful remote control script looks like:

• Some DNS and ARP
• Setting up of TCP sessions with 3-way handshake.
• RPC and DCOM constraints
• Many TCP handshakes
• Kerberos (computers in a domain)
• Multiple RPC / DCOM
• Many TCP handshakes, many Kerberos, RPC / DCOM are associated with TCP communications.
• Many DCOM are followed by previously established TCP sessions.

All of that takes about 2 seconds. Now let's look at the capture for ChangeIPAddress.vbs (the script generated an RPC error when running it remotely) and see how it differs from the above scenarios.

1 0.000000 NetmonFilter NetmonFilter: Updated Capture Filter: None 2 0.000000 NetworkInfo NetworkInfo: Network info for TEST124, Network Adapter Count = 1

It is Netmon

3 0.000000 {DNS: 3, UDP: 2, IPv4: 1} test124.test.local dc181.test.local DNS DNS: QueryId = 0x7869, QUERY (Standard query), Query for test125.test.local of type Host Addr on Internet class 4 0.000000 {DNS: 3, UDP: 2, IPv4: 1} dc181.test.local test124.test.local DNS DNS: QueryId = 0x7869, QUERY (Standard query), Response - Success 5 0.015625 {ARP: 4} 172.16.11.124 172.16.11.125 ARP ARP: Request, 172.16.11.124 asks for 172.16.11.125 6 0.015625 {ARP: 4} 172.16.11.125 172.16.11.124 ARP ARP: Response, 172.16.11.125 at 00-11-D8-E3-EC-84 7 0.015625 {TCP: 6, IPv4: 5} test124.test.local test125.test.local TCP TCP: Flags =. S., SrcPort = 1063, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 539163285, Ack = 0, Win = 65535 (scale factor 0) = 65535 8 0.015625 {TCP: 6, IPv4: 5} test125.test.local test124.test.local TCP TCP: Flags =. S. A., SrcPort = DCE endpoint resolution (135), DstPort = 1063, Len = 0, Seq = 981335265, Ack = 539163286, Win = 65535 (scale factor 0) = 65535 9 0.015625 {TCP: 6, IPv4: 5} test124.test.local test125.test.local TCP TCP: Flags =. A., SrcPort = 1063, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 539163286, Ack = 981335266, Win = 65535 (scale factor 0) = 65535

ARP, then NDS, TCP handshake - as before.

10 0.015625 {MSRPC: 7, TCP: 6, IPv4: 5} test124.test.local test125.test.local MSRPC MSRPC: c / o Bind: UUID {99FCFEC4-5260-101B-BBCB-00AA0021347A} DCOM-IObjectExporter Call = 0x1 Assoc Grp = 0x0 Xmit = 0x16D0 Recv = 0x16D0 11 0.015625 {MSRPC: 7, TCP: 6, IPv4: 5} test125.test.local test124.test.local MSRPC MSRPC: c / o Bind Ack: Call = 0x1 Assoc Grp = 0x32EA Xmit = 0x16D0 Recv = 0x16D0 12 0.031250 {MSRPC: 7, TCP: 6, IPv4: 5} test124.test.local test125.test.local DCOM DCOM 13 0.031250 {MSRPC: 7, TCP: 6, IPv4: 5} test125.test.local test124.test.local DCOM DCOM 14 0.078125 {TCP: 8, IPv4: 5} test124.test.local test125.test.local TCP TCP: Flags =. S., SrcPort = 1064, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 1367843928, Ack = 0, Win = 65535 (scale factor 0) = 65535 15 0.078125 {TCP: 8, IPv4: 5} test125.test.local test124.test.local TCP TCP: Flags =. S. A., SrcPort = DCE endpoint resolution (135), DstPort = 1064, Len = 0, Seq = 3625279350, Ack = 1367843929, Win = 65535 (scale factor 0) = 65535 16 0.078125 {TCP: 8, IPv4: 5} test124.test.local test125.test.local TCP TCP: Flags =. A., SrcPort = 1064, DstPort = DCE endpoint resolution (135), Len = 0, Seq = 1367843929, Ack = 3625279351, Win = 65535 (scale factor 0) = 65535 17 0.078125 {UDP: 9, IPv4: 1} test124.test.local dc181.test.local KerberosV5 KerberosV5: TGS Request Realm: TEST. LOCAL Sname: RPCSS / test125.test.local 18 0.078125 {UDP: 9, IPv4: 1} dc181.test.local test124.test.local KerberosV5 KerberosV5: TGS Response Cname: Administrator

RPC, then DCOM, another TCP handshake, Kerberos. It looks the same as before.

19 0.078125 {MSRPC: 10, TCP: 8, IPv4: 5} test124.test.local test125.test.local MSRPC MSRPC: c / o Bind: UUID {000001A0-0000-0000-C000-000000000046} DCOM-IRemoteSCMActivator Call = 0x2 Assoc Grp = 0x32EA Xmit = 0x16D0 Recv = 0x16D0 20 0.093750 {ARP: 11} 172.16.11.125 172.16.11.181 ARP ARP: Request, 172.16.11.125 asks for 172.16.11.181 21 0.093750 {MSRPC: 10, TCP: 8, IPv4: 5} test125.test.local test124.test.local MSRPC MSRPC: c / o Ack: Call = 0x2 Assoc Grp = 0x32EA Xmit = 0x16D0 Recv = 0x16D0 22 0.093750 {MSRPC: 10, TCP: 8, IPv4: 5} test124.test.local

FAQ

What is Managing Windows Networks Using Script -- Part 8: Handling Remote about?

It provides a structured overview of tcp, explains the main context, and highlights practical takeaways for readers.

Why does this topic matter?

Understanding the main concepts helps readers evaluate the issue, avoid common mistakes, and make better-informed decisions.

How should readers use this information?

Use the guidance as a practical starting point, confirm details that may have changed, and follow current product, safety, or security recommendations.