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Yes, you are right; there are problems with using the ndisapi.dll binary included within the WinplFilter package. The problem was caused by moving the NDISAPI project from one building environment to another so the routines exported through the DEF file were not exported anymore (this binary also is not possible to use with Delphi). We appreciate you report, WinpkFilter packages with fixed ndisapi.dll binary will be available for download in the next few days.
Fixed binary also available for download from the following link http://www.ntkernel.com/downloads/ndisapi.zip
Since WinpkFilter 3.0 we provide the complete source code for the ndisapi.dll in the freely available packages because of different building environments you may have to use. So, you can modify/port/rebuild the ndisapi.dll or even integrate it into your application.
Some others functions doesnt respect the functions declarations presented in the Help.
Could you please provide the details?
Well, DomainSuffixTool.exe is not relative to NeT Firewall. I guess that you already uninstalled NeT Firewall, and DomainSuffixTool.exe belongs to some other software you had tried and also uninstalled but not completely. I’d advise to check autorun and registry keys associated with application auto start up in order to detect the exact reason.
Blocked packets in the log were blocked by TCP stateful inspection module (these packets could be retransmitted/duplicated packets or corrupted during transmission, these could be also malicious packets but I don’t think this is the case).
You can disable TCP statefull inspection in the firewall options, but I would not recommend it.
Since Sygate firewall discontinued by Symantec it won’t cause compatibility problems anymore.
http://www.geek.com/news/geeknews/2005Nov/gee20051130033532.htm
pIpHeader = (iphdr_ptr)(pPacketBuffer->m_IBuffer + ETHER_HEADER_LENGTH);
pTcpHeader = (tcphdr_ptr)(((PUCHAR)pIpHeader) + sizeof(DWORD)*pIpHeader->ip_hl);pIPHeader = (iphdr*)PacketBuffer.m_IBuffer+14;
Typecasting has a higher priority than operator + above. You have to change it to:
pIPHeader = (iphdr*)PacketBuffer.m_IBuffer[14];
or
pIPHeader = (iphdr*)(PacketBuffer.m_IBuffer+14);
Can I limit bandwidth using winpkfltr for each ip/source combination?
Yes
If so, Please give me some directions on how to do this?
The basic idea is pretty simple. One possible realization is the following. Create a queue and put all packets into. Also create a periodic timer and each time when timer fires calculate time passed since last timer. Then claculate the amount of data you can allow to pass for the given time and process as many packets from the queue as it fits into clculated amount of data.
Can I use Winpkfltr to look at the ip header and make a decision on to drop/forward the packet?
Yes. You can take PassThru sample as a base. If you decide to drop the packet just don’t reinject it into the stack (by calling SendPacketToAdapter or SendPacketToMstcp).
This function should be able to drop or forward the packet based on some criteria. But here is the problem:
I dont want to drop all packets going to certain ip and port. For the same ip and port, I only want to drop say 10% of the packets and for some other ip/port, drop 20% of the packets.You can use kind of random generator, like C run time rand() routine.
An example, 20% chance of drop may look like:
if (rand() < RAND_MAX/5) bDrop = TRUE;I am trying to compile PAssThru in cbuilder folder.
I use:
bcc32.exe PassThru.cppHmm, I would start Borland C++ Builder, select File->Open Project, browse to PassThru.bpr and open it. After this I would click Project->Build PassThru.
it gives me many unrsolved external sybol errors. I understand that these are caused by the linker and I probably have to link it with ndisapi.dll, but I dont know how to do this.
Actually, you have to link to ndisapi.lib (stub library for ndisapi.dll).
As it is stated on VirtNet page it is just dummy network interface which does not do anything special itself (similar to MS loopback adapter, but supports all Windows operating systems). However, when used in combination with WinpkFilter you can build various virtual network environments over it.
WinpkFilter can be used for implementing two major tasks:
1) To indicate packets from the name of VirtNet to TCP/IP stack.
2) To intercept packets sent by TCP/IP stack to VirtNet network interface.You can create pure virtual network environment or bridge it to the real network or …. Actually, it depends only from you requirements.
So, Net firewall is full functional also if no one is logged on the system.
It’s right?Right
How can I see log of Firewall activity before I log on?
Log is not collected if firewall console (MMC snap-in) is not loaded, so in the current version there is no way to look through packets processed before logon.
NTKernelService stats dirung system start up, load latest firewall configuration into the driver and exits. So the situation you have expirienced is normal, this service should not be running, all the packet filtering functionality implemented in the kernel mode driver. Service is only responsible for configuring it.
If I add a rule allowing external access to one of those IP’s, all the others get accessable too. Why is that?
It should not be, probably the rule you create is too common and covers more than one IP.
Could someone please list a standard ruleset for allowing all traffic to port 80 on the server only. I know it’s very basic but it would be great to make sure I did it right.
Allow, TCP, Source IP: Any, Source Port: Any, Destination IP:[IP address your WWW server is bound to], Destination Port:80 Bidirectional.
Also set the security level to high.
I found a few bugs playing about. Are you interested in fixing then if i detail the issues?
Sure, if you find any bugs we would appreciate reporting about…
Do you also properly adjust DNS records length? (See dnsr_rdlength in the dns_record structure on the following link http://www.chiark.greenend.org.uk/ucgi/~richardk/cvsweb/dns/dns.h?rev=1.8&content-type=text/x-cvsweb-markup)
