On Thu, 2025-08-07 at 01:38 +0000, Grant Edwards wrote: > According to IANA (and before that ICANN and USC/ISI) port numbers > from 1024 to 49151 are registerd ports, and are to be used for > specific protocols. For example ports 2222 and 44818 are registered > for used by the Ethernet/IP Rockwell PLC protocol. > > Dynamic or ephemeral ports are supposed to be in the range > 49152-65535. > > Linux defaults to 32768-60999 for ephemeral ports. That clearly > overlaps with a _lot_ of assigned/registered port numbers in the > range > 32786-49151. > > That seems just plain wrong. What am I missing? > > It's simple enough to change the ephemeral range so it doesn't > overlap > with registered port numbers, and it looks like I'm going to need to > do that to avoid possible collisions in a project I'm working on. The > question is why do I have to do that? The standards are pretty clear. > Why does Linux default to being broken like that?
its mostly legacy stuff and convention. at the end of the day, a port is a port is a port. nothing more to it. that thing... 1->1023 is true. kernel actually wants you to be root to bind those ports, but truth be told, all programs drop privileges. smtp. imap. pop3. to make a few. they dont run as root. they start as root and then drop privileges. so why even have the kernel thing in the first place? tradition. inertia. a port is a port is a port.
