Re: Wireshark Download For Windows 10
Phyllis Sterlin
Recently, I have had problems getting Windows Update and Windows Activation to work. This is a network level problem, not specific to any one machine and affects both servers (WS2012r2) and desktops (Win 10 Pro), both physical & virtual machines. Sometimes, the problem resolves itself if I let the PC sit for a few days, but usually not - and never for activations.
I've been through all of the "fix Windows Update/Activation" steps, multiple times with multiple machines without success, so I did a clean install on a test machine with Wireshark installed. I'm not going to post Windows error codes here because I just want to find out what Wireshark can tell me about these failures.
You are looking at countless attempts of the machine to set up a TLS-encrypted connection with the Microsoft update server. As the encryption uses Diffie-Hellman key exchange, there is no way to decipher the payload and even the result of the handshake unless you would use a MITM-attack on it. But it seems that there is actually no payload at all, as after the end of cipher suite negotiation, the client actively closes the TCP session without transferring any TLS payload at all.
So if we leave aside a bug of the Microsoft upgrade client, the only idea I could have would be that some security element between the machine attempting the upgrade and the Microsoft server (reverse DNS shows that 157.56.96.58 does belong to Microsoft range) tampers with the Diffie-Hellman exchange and the client recognizes it somehow (or the server does and says the negotiation has failed).
If you can isolate one of the machines from the rest of the network and let it bypass your current security elements (firewalls) when talking to the internet, and if it upgrades successfully this way, you'll know there is something wrong about your firewally.
Another thing which surprises me is that your machine sends a DNS request, asking for an IP of ctldl.windowsupdate.com, but doesn't wait for a response for a reasonable amount of time, as when the answer arrives in less than two milliseconds, it is already rejected with icmp "destination port unreachable". Normally, DNS responses coming within seconds are still awaited and accepted.
That's more-or-less what I thought was going on. Why it's happening is still a mystery, because I have the local (Windows) firewall turned off, and Defender disabled (as much as it can be) with no effect. I've also temporarily set our WAN firewall to not restrict outbound traffic and enabled WAN ping response as a test - again without effect, and there are currently no intermediary firewalls in place.
This may or may not help. Some of the security boxes behave funny and interfere with the traffic even if configured not to do so, so when I said "bypass", I really had in mind "bypass", i.e. connect the machine under test in such a way that its communication to the Internet does not go through that security box at all.
If you only have physical machines, connect one of them somewhere else where network security is provided by another type of security box, or just switch on the security software provided Windows itself and use a mobile connection (Public network setting of Windows networking).
I finally tracked the problem to our Meraki firewall incorrectly identifying certain CDN IPs as belonging to malware domains, and silently blocking them. There were no logs showing the blocking, as Meraki apparently doesn't think admins would need that information.
I have run into the TCP Window Full message and want to be clear about which side the issue is on. I am running a capture on a server and it is capturing traffic being sent from a remote site over a site to site VPN. When I see the message the packet its in is showing source as the server and destination as the remote site firewall... Does this mean the server is running dry and processing power and reporting its buffer is full. I note I see a TCP update window a few packets later from the firewall sending it to the server which then confuses me, maybe its unrelated to the buffer being full on the server. Also is this the same as a zero windows condition? Thanks I'd like to get as much info as possible around this : ) thanks
"Window Full" from Wireshark means that Wireshark has calculated that the current packet will fill the receiver's buffer. In order to calculate this correctly, Wireshark has to have captured the TCP three-way handshake so that it knows if window scaling is in use, and if so, what the scale factor is. Window Full is normally, but not always, followed by zero window from the receiver.
The receiver's window is filling up because the application is not reading the data out of the receive buffer as fast as it is coming in from the network. The application is not keeping up. Sometimes Window Full might not be followed by zero window because right at that point the application swoops in and starts reading data out of the receive buffer while the packet with the Window Full message is in transit, so the receive buffer doesn't actually fill up, although it comes close.
However, most of the time, Window Full will be followed by zero window. If you see a lot of Window Full messages, and they are not followed by zero window, and you didn't capture the three-way handshake, then that is a clue that window scaling is in use and the Window Full message is wrong, because Wireshark is not able to calculate the true window size.
Wow wireshark sure is tricky. I'm only learning but it seems to be difficult to be confident when identifying an issue. There are so many other factors that come into play (lots of red herrings!). I'm using the chappellU videos but is there any where else worth looking at to upskill. I've met quite a few people that have a knowledge of wireshark functionality but none that were confident to pinpoint problems and provide wireshark data to back it up : )
Each time I start WS I get this popup about admin-mode being allowed to make changes. I select yes or no and it continues to popup making WS unusable. Has anyone come across this? I believe it's related to npcap being used in admin mode only or something like that. I have the 64 bit latest version downloaded directly from wireshark.org.ej
I got it to work this time by uninstalling, rebooting and reinstalling, for the 3rd time, and the only option I selected was to allow npcap to be winpcap compatible. I left the run only as admin function for npcap and the rest unchecked. It appears to be working.
It's the npcap option to require admin privileges to capture that causes this behaviour. This is not checked by default (the npcap installer may remember options from a previous install though) and should not be checked unless you need, or are required by some local policy, to do so.
I have run Wireshark on both the guest and the host. Curiously, if I send the packet to another computer, the packets are captured without problem in the second machine. I don't understand how I cannot capture the packets in the machine that is sending them.
When guest OS is set up, a network interface is assigned to it.
Is wireshark listening on that interface?
In linux, there is an option to use "any" interface, which listens on all possible network interfaces, but I don't know if such option exists on the windows.
In my experience Wireshark only sees the host's really external network interfaces. For example, if you use a web browser to look at a web page served by a web-server on the same PC ( ), you can't use Wireshark to look at this traffic.
Similarly, the delivery of data by the VM to the host is local and not directed through a physical NIC. Presumably this provides no structure in the host operating system that looks like a "network interface" to Wireshark.
As of March 18, 2022, Wireshark can capture traffic on the Loopback interface. There is a dashboard when the application opens with a list of network interfaces. Double click on "Adapter for Loopback Traffic Capture".Wireshark needs to use the npcap packet capture library for loopback traffic to be detected.
I'm assuming you're on Windows (based on the path C:\Program Files\Wireshark). This isn't really a Wireshark question, it's a Windows command line question. The following works for me on Windows Vista:
This syntax is dependent on your locale and exactly how the date is displayed on your system, so you might have to tinker with it a bit. If this doesn't work for you, Google on "windows date filename" and you'll get dozens of results showing various commands for including the date in a file name from the command prompt. On my computer, the output of the 'date' command is displayed as "Wed 09/12/2012".
A ring buffer normally writes multiple files, but by setting the autostop (-a) option duration to the same value as the ring buffer (-b) option duration, tshark will only write one file, which is what your command above does. (However, an hour can be a long time to capture on a busy network, so you might want to consider using a ring buffer option that writes multiple files over the one-hour period.)
I have my PC connected to a CISCO switch port with the port in SPAN - However I see some traffic initiated by the PC. these appear to be broadcasts of Netbios name resolutions I tried changing the binding on the port and removed all protocols - that shuts the port down and I can not use it for capture. I happen to have Airmagnet software installed on this PC and binding it just to that does appear to work.
Is there a way on windows to keep the port up but not have it used for anything so I can see only traffic initiated from elsewhere? For example a "Wireshark capture protocol" that can be selected for the port? TIA Ross
I operate in this manner all the time with my WindowsXP, Windows7, and Windows8.1 OSs. I deselect all the bindings and then can only receive traffic, which it does. I recommend this to my colleagues when they have a dedicated wired sniffing adapter. This works with Linux as well if I zero out the IP address.
d3342ee215