[TriLUG] Port Numbers (was: email (imap) setup question)

[Ben Pitzer]

Folks,

/etc/services, as Mike said, is a good place to start, however it is not
comprehensive.  On some systems, ports are left out of /etc/services, so if
you don't see what you're looking for in there, don't panic.  In that case,
Lisa's reference page is spot on.  I usually refer to my local system first,
but have had to look elsewhere in the past.  I hadn't seen that IANA page
before, but I've book marked it for future use.  You Solaris users, for
example, remember:  port 22 is not listed in /etc/services by default.  You
may need to add it by hand.

Regards,
Ben Pitzer

---------------------------------------------

"Those that can give up essential liberty to obtain a little temporary
safety
 deserve neither liberty nor safety."
 --Ben Franklin--





> -----Original Message-----
> From: trilug-admin at trilug.org [mailto:trilug-admin at trilug.org]On Behalf
> Of Mike Johnson
> Sent: Wednesday, January 01, 2003 11:28 AM
> To: trilug at trilug.org
> Subject: Re: [TriLUG] Port Numbers (was: email (imap) setup question)
>
>
> Jim Ray [jim at neuse.net] wrote:
> > Good stuff.  I can't remember which port is which.  They say the mind is
> > the first to go.
>
> There's also /etc/services for the more well known protocols.
>
> > Question:
> > How come the ports for SMTP, HTTP, etc indicate UDP and TCP?  I thought
> > they used TCP.  I locked down this server so tight that nothing worked
> > at all.  It was really cool.  Now, I'd like to selectively unlock it.  I
> > tried TCP to no avail and think I might add UDP as well.
>
> A lot of protocols have both TCP and UDP registrations, that doesn't
> mean they use them.  Your normal SMTP and HTTP traffic is explicitly
> TCP.  There's no need (or reason) to open 25/UDP and 80/UDP.
>
> > On DHCP, is that the same thing as bootstrap protocol?
>
> Sort of.  DHCP uses the BOOTP port (67/UDP for the server), but the
> protocol on the wire is a bit different (you can cram more info in the
> DHCP protocol).
>
> Mike
> --
> "If life hands you lemons, YOU BLOW THOSE LEMONS TO BITS WITH
>  YOUR LASER CANNONS!" -- Brak
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>