We (our lab) recently upgraded to Ethereal 0.10.14 with WinPCap 3.1. If I remember correctly, we had previously been using 0.10.2 with WinPCap 3.0. However, since the upgrade we have been noticing several issues.
The first issue is with "TCP Previous segment lost" and "TCP CHECKSUM INCORRECT" messages appearing in the Packet Listing window. We do not remember seeing these in the previous version of Ethereal, or at least not nearly as many as we are seeing now. For example, one task for the student instructional part of the lab involves visiting a website containing two images and observing the network activity. After the two GET requests are sent for the images, it is not uncommon for one image to be returned with a typical 200 OK response packet, but the response packet for the other image will be displayed as "TCP Previous segment lost." However, both images are downloaded and displayed perfectly fine in the browser. I would think that the segment lost error would mean the object wasn't returned correctly and shouldn't be able to be displayed, but apparently that is not the case. (The cache had been cleared when this was performed, so it was not defaulting to a local copy of the image.)
Another problem we've been noticing is that some packets simply aren't displayed in the Packet Listing window, even when they are obviously received. Using the same example as above, after the two GET requests are sent for the images, it is not uncommon for one image to be returned with a typical 200 OK response, but the other response will not appear. Yet both images are successfully displayed in the browser. Is this a problem with Ethereal not detecting the packets?
I'm not sure how typical this is, but we seem to be experiencing these issues often with 0.10.14 while we never did with 0.10.2. Could it also be an issue with WinPCap, and not necessarily Ethereal? I'm just trying to find some answers as to why we are seeing a sudden abundance of TCP related errors and uncaptured packets. Thanks.