Is the FTP server listening on the standard FTP port of 21?ĭo you have other clients that are able to use FTP successfully to the same server? If you haven't already done so, asking the users/customer some questions such as:ĭoes it experience the issue every time or only intermittently?Īre they using passive versus active FTP and does the opposite method work? Jumping to packet captures as the first method of troubleshooting an issue should never be the case. That being said, I think some additional context might be helpful.

You may also need to capture on both the inside and the outside interface, in case the firewall itself is what is contributing to the issue. I saw that you mentioned setting the external IP as the source IP in a filter ACL applied to the packet capture, but you'll actually want to set it as the source and the destination, so that you capture bi-directional traffic.

The recommendations others have made regarding running the capture on the ASA are all good. This will be running for about a week since we don’t know exactly when these FTP transfers happen. I am leaning towards using Wireshark, but if we can do it on the ASA with out any risk that would be nice.

He is worried that running the captures on the ASA will be too labor intensive, and doesn’t want to cause any network issues/outages as this customers network is already a little unstable. My question is, would we be better off hooking up a laptop directly to the ASA with Wireshark running on it, or could we run the packet captures on the ASA itself? My senior engineer said that we could do it on the ASA, but my manager is uneasy about it. This customer recently got a new WAN circuit installed and this is when they started having these issues. I was tasked to run packet captures for about a week or so, so that we can monitor/take a look at the traffic and see what is going on (whether the files are coming in corrupted from the WAN, or if there are issues internally and/or why they are being dropped). I recently got thrown an issue by one of our customers where they are having issues with receiving external FTP files.

Wireshark packet capture on test ftp