Re: Re-connecting

John Drake wrote:

> And yet MANY lists of "common ports" show POP3
>
>running BOTH on TCP AND UDP.  Good grief, people
>act like I'm making this up.  Anyway, I see no
>reason for assinine comments like "are you smoking
>something" or "you're being silly" or whatever.
>
>  
>
Maybe they're all derived from the same list. Maybe it's just a standard 
way of setting them up. Maybe POP2 had a UDP implementation once and the 
POP3 list was derived from there...

Set against that, you have the RFC, the very nature of a POP3 connection 
(which last time I used telnet to port 110, assumed a constant 
connection between the two machines, the dropping of which would signal 
the end of the connection), and a noticeable paucity of POP3 servers 
that advertise UDP support.

You're taking one source that says what you want to hear and saying that 
all the sources that contradict it are wrong. Well, you're welcome to do 
that, but it's verging on the solipsistic. Alternatively you could 
consider that perhaps the common ports list is the least authoritative 
source that's been brought up so far... since its only function is to 
give numeric ports human-readable names.

> Yeah, I'm aware of the advantages of TCP over UDP.
>
>I'm aware that TCP is connection oriented and UDP
>is "connectionless".  And yeah, I wouldn't want
>to not get my email.  Yet UDP is used for TFTP.
>Wouldn't it be bad not to get the last few bytes
>of a 10 MB file coming down over a 56K connection?
>  
>
It would, but since TFTP (_trivial_ file transfer protocol) is designed 
purely for booting servers with and is hopelessly insecure, anyone 
seriously doing such a thing should be shot... and of course, if you 
don't get the last K of your kernel from the LAN, it's a lot more 
solvable - you just reboot. There was a real file transfer protocol that 
used UDP; it was called FSP - but I don't have happy memories of using 
it. FTP (which is robust, stable, complex, and can be made secure) uses TCP.

>This is the bottom line.  For WHATEVER reason
>some POP3 servers are listening on UDP.  
>  
>
Please provide an IP address of one... or at least a reference to some 
code we can actually run for ourselves that supports that assertion. At 
the moment, all I can see that you have to go on is one line of one 
widely-dispersed file, which I dare say not even its authors would claim 
was authoritative, and I think it's worthwhile pointing out that if 
you're expecting to be able to talk to your ISP's POP3 server using UDP 
then you're highly likely to be disappointed...