Originally Posted by acid_kewpie
looks like you want the -sY flag according to the manpage. The combined request for a traceroute AND an SCTP INIT scan suggests it will do what you want.
I did use -sY and also -sZ. It apparently did scans in SCTP. It could not reach the target in SCTP (blocked in or out I do not know). So when it came to the step to do a traceroute, it did it in TCP, instead, and even stated that it was doing it in TCP because that was more likely to reach the target. That design seems to be intended to answer "What is the path to my target by whatever means that can work" whereas my question is "Where along the path to my target does a specific protocol fail".
And the man page section even says this, so I suspect Nmap may not be able to do what I want. ... "using information from the scan results to determine the port and protocol most likely to reach the target" ... not what I want. I want to specify the port and protocol.
I don't even need to do the scans Nmap does. I just need to do traceroute alone. But I need to do it specifically in SCTP. Apparently the -s options only specify what the scans are done in.