Ex Windows programmer trying to evolve to Mac... please go easy. :-) As part of my transition I'm trying to get some older stuff I wrote for myself to work. I have a command line utility program which uses socket(), connect(), send(), select/recv() to create a RAW socket and send a ICMP_ECHO packet to a host and then await its return. Essentially, PING with some minor variation in its output. Got it built in Xcode. Found that socket() with SOCK_RAW failed until I ran as root (via SUDO). OK, no problem. Now it sends, but it never receives a response. The select() always times out rather than receiving the reply. When I run my Windows cmd line version on the same machine under Parallels, it works fine. So I'm confident the other host is able to be reached from my network, etc. I can use actual PING from the command line just fine too. Is there some other permission facility in MacOS that would prevent me from receiving the reply packets? What would it be called, how would I either turn it off or work with it? Thanks for any help!