I believe I have now answered my own question. Thought I had taken a close enough look at the sysctl() library function, but I hadn't! For example, the following will yield information about the current TCP connections:
sysctlbyname("net.inet.tcp.pcblist", ...)
To get information about UDP connection, simply use a different Management Information Base (MIB) name: net.inet.udp.pcblist.
For convenience, here's a link to the appropriate iOS man page:
http://developer.apple.com/library/ios/#documentation/System/Conceptual/ManPages_iPhoneOS/man3/sysctlbyname.3.html
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…