I am working on project that can capture the data passed from the user to the network in the same machine and modify its contents.
But I don't know if Winpcap can only capture or can also modify the data???
I hope my question was so obvious for you!
You can capture. You can modify what you capture, but that doesn't affect what goes through the network stack: only what you have in your own sniffing process. You can't filter packets out either.
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I am new to windows filter drivers. From the sample code of (MSDN) what I have seen is that, File system filter driver, has Filter Manager associated with it, and process filter driver doesn't have Filter Manager associated with it. So why is that difference?
So need some suggestions and help.
It seems that you might want to read Windows Internals by Alex Ionescu, this will clear things up for you, starting from the bottom and will help you understand the whole thing.
Basically, in the past, filesystem filter drivers were built in a way that it would sit in a the right position in the exact filesystem DEVICE STACK, for example, NTFS. That way it would get the chance to filter IRPs.
Nowadays, the thing you mentioned, the filter manager (FLTMGR) has its own (legacy) driver at the top and on the bottom of the device stack, and it lets you register a callback function that everytime an IRP gets caughted, you'll get a chance to handle it.
Process (creation/deletion) filtering is a bit different, it is not handled using IRPs, basically in the call flow of NtCreateUserProcess on the kernel side there is a function responsible for calling whatever function registered for this kind of callback.
I hope that it clears things for you.
I'm reading packets with wireshark and most of these packets are repeating multiple times per second (identical). I don't want to see those. They're too many to manually filter (thousands).
So what I'd like is some filter like:
This packet was already captured/displayed, I won't display it again.
Is this possible using wireshark or is any other software (linux) available for this? I definitely need this feature in live capture so doing some magic with a dump file is not an option.
I am trying to automate the process of capturing network packets send by a particular application.I don't have problem in windows as I am using Microsoft Network Monitoring tool and that gives all the traffic send based on the process.Now the problem is that we need to achieve the same result in mac as well.
We used Wire-shark in mac for capturing network traffic after a long research but still wireshark does not capture by process name.We tried some tools that captures based on process name but with very limited information. We need the full packet informations to be captured.
What will be the best way to achieve the result in mac as like we are getting in windows?
what all parameters can be used to filter the wanted data...?
I am in fact trying to get the port number used by the process but is that a right approach ? I am not sure we can zero down based on port number.
Any help would be greatly appreciated...
Thanks in advance...
You can use lsof command, but it's more complex than netstat.
Here is a guide: lsof survival guide
I need to dump some incoming packets and then prevent them from going up the stack, so that applications won't process them.
Now, tcpdump works at layer 2, right? So ideally I should find some tool that I'd use right after tcpdump that drops selected packets. The filter I apply in tcpdump and when I drop packets is going to be the same.
Anything that already does this?
Now, tcpdump works at layer 2, right? So ideally I should find some tool that I'd use right after tcpdump that drops selected packets.
Tcpdump captures from a network at the link layer, yes. However, "captures", in this case, means "passively taps into the network, getting copies of all packets received and sent". It does not tap into the network in a fashion that allows it to prevent those packets from being processed by the network stack. Think of it as being similar to tapping a phone line - whoever's tapping the line can listen to the conversation, but they can't prevent somebody on one side of the conversation from hearing what the person on the other side says.
Anything that already does this?
There might be, but the mechanism that it would use to do so is probably going to be very dependent on the operating system it's running on. What operating system is the machine on which you need to trap the packets running.
I am trying to find a solution to monitor the traffic (in and out) through a specific port. It is not required to capture the packets, or do anyting else. What it does is to be a traffic listener to make sure there are messages sent to or received from this port every 10 minutes. It has to be running at the background all the time (like a daemon), and without significant performance impact. Based on my research, one choice is to use an existing tool to do that. There are a bunch of tools out there to monitor or sniff the traffic, such as wireshark. Well, seems most of them monitor the traffic passing through a interface, instead of a port, or they can't run as a daemon. Another choice to write a program to do this. SharpPcap seems to be a good choice, but I still need to capture and analyze the packets to know whether such traffic exist. Could somebody suggest what I should do?
SharpPcap handles packet capturing in the same manner as Wireshark, so you can set filters to limit the packet being captured to a specific port the same way in SharpPcap as you can in wireshark. Except, SharpPcap will be a much lighter weight option vs wireshark.
Download the SharpPcap source tree and look at the Example05.SetFilter.
To narrow down the results so you capture only the packets you want to see you'll need to employ a few filters.
Pcap uses a common language across all applications that use it do specify the filters to set. Capture programs that use winpcap (windows) or libpcap (*nix) include, sharppcap, wireshark, pcap.net, winpcap, libpcap, tcpdump, etc... For a great resource on how to use pcap filters see this link.
Here are the filters you need:
ether host ehost
port port
Where the ehost is the MAC address of the computer sending/receiving the packets and the port is the port you want to monitor. So the full filter string would be.
SetFilter("ether host ff:ff:ff:ff:ff:ff and port 60");
The MAC and port here are for illustration purposes only, you'd obviously change them with the values that pertain to your specific setup.
This, used in the SetFilter example will simply print out a line of info with the time of when the packet was captured to the command line every time a packet is captured and meets the criteria if your filter.
If you want more detailed info about the packet, such as info from the headers or the packet's payload, you'll need to parse the incoming raw packet. Be sure to ask for help on the sourceforge project's forum if you need some tips on how to do this. The project developers are very active and always willing to help.
The best way that will limit the impact your tool will have on performance is via an ETW (Event Tracing for Windows) Real-time Consumer (i.e. a tool that activates an ETW trace and reads it immediately instead of saving it to a file). This MSDN sample is a great way to see how to do this via C# and it gives you some code to get started.