we experience this issue in our network:
a test probe is running ftp requests to a server in order to measure performance between two point of the network.
The ftp uses port TCP:5060 that is a well known port for SIP. The easy conclusion that it is a non sense and that this ftp test should change its connection port is not enough for some people, it is mandatory to make this test work with this configuration. We are trying to understand where should this dirty connection be aborted, the first security device is ASA. ASA has SIP inspection enabled and, as I understood, it considers UDP/TCP:5060 by default (even if in most cases SIP runs over UDP).. is it possible that this inspection block FTP traffic over SIP port? We would maintain SIP inspection active while enabling this FTP traffic: I found the SIP inspection parameter 'traffic-non-sip', could it help with our issue?
An additional information is that ftp client generates SYN but it doesn't receive any SYN ACK: if something blocks, it blocks from the very beginning of the connection.
Thanks a lot