At 12:11 2004-02-03 -0800, Bart Schaefer wrote:
> No guarantee that the port will be unused by any other process, and UID
> assignments are pretty wild in some installations, but you could always
> look at making it a base of some high port + the UID value.
That's a good idea, though I'd be afraid the UID-number space might be
larger than the port-number space.
UID limits have traditionally been 32K or 64K, depending on OS form. This
poses limitations for extremely large organizations (or, say,
universities), say which use Radius in conjunction with a central unix user
db. But, as I said, the viability of that approach rather depends upon the
range of UIDs in use.
TCP ports are limited to 64K, with the low 1K or so reserved for privledged
user only (Jack Idjut can't fire up a port-80 webserver from user
space). Where one used to see ":8080" in a URL, this often meant that the
webserver was being run by a user, rather than the system admin (indeed, a
subscriber-user on a host could run a webserver which has the same domain
name of the ISP host, and Jack Schmuck on another ISP wouldn't inherently
know that some link he'd followed - which specified a portnumber - wasn't
the "official" company website).
Usually though, one doesn't have quite so many users on a single host, and
mega ISPs providing PPP service generally don't offer SHELL access, so
their users don't need to correlate to a unix user db.
Take a peek at the /etc/passwd file to see what sort of UIDs are in use in
your case.
---
Sean B. Straw / Professional Software Engineering
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Please DO NOT carbon me on list replies. I'll get my copy from the list.
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