As I told someone else, this isn't exactly what was proposed but it is
sorta. HUH??
So far no one has been able to access & use from a pseudo-domain/pseudo
user account? To date, all tries have been from valid domains by valid
accounts on those domains. No try, to my knowledge, to come into port
25 & pretended to be me or [EMAIL PROTECTED] [as proposed in the
message that started this whole discussion] has succeeded.
Since the way mail gets passed from server to server around the world
*has* to depend upon jumps through multiple servers, I guess that mail
from a valid domain/user or SMTP server could always be accepted for
forwarding or local delivery [don't want to have to leave the premises to
send local e-mail, right?]. I think, if I've followed some headers
correctly, that although the route is shown in the headers, only the
last/current sender is validated. Otherwise, how could all that spam be
spewn across the world?
But I don't think I could telnet in from the VA hospital, cuz I'm not an
"authorized user" even if I did manage to get behind the windoze facade
and plug into telnet ... I might be able to telenet to my home ISP, but
when it came time to send the message ... or before??? ... I'd suddenly
be a "Sender NOT OK" because the computer at VA would stutter and raise
holy ned when asked for validation.
Now what would then happen at that point I don't know ... but apparently
I could be queried for login?? Heck, it's been so long since I even
telnetted locally I don't know that I could do it any more.
I imagine that among this group is at least one individual who could
manage to set up some sort of shield and create a false 'id' to contact
[and respond?] to the server, but I don't know that the server could
then be fooled into believing that false info was acceptable. Anyone
know precisely how a server checks on the validity of a sending address?
Is it a DNS kinda thing, or is it a matter of polling the "originating"
server to see if the account information is valid, or ???
The experimental will go on, I guess. I'm waiting for more info from
the techie... :>
l.d.
====
On Tue, 6 Feb 2001 08:30:13 +0100, [EMAIL PROTECTED] (Howard Eisenberger) wrote:
> On Mon, 05 Feb 2001 18:28:53 -0500,
> "L.D. Best" <[EMAIL PROTECTED]> wrote:
>> I wasn't going to reply, because it would just be another case of "no
>> win" ...
>> I will, instead, simply state that my ISP made clear a number of things
>> about the types of firewall protection they have:
>> 1. The SMTP server will not "open relay."
>> 2. If the need arose for me to telnet into the servers, for mail
>> tossing from foreign site [like when I'm stuck in the VA hospital], they
>> would consider giving me a username & password that would allow it;
>> without the username & password, it would not be possible to do.
> I assume you are talking about telnetting to port 25 (smtp) and not
> port 23 (telnet).
> Before all this authentication business, they would have probably
> told you to use the smtpserver at the VA hospital, period.
> Authentication is less restrictive than IP-based protection. Also,
> users don't have to change the smtpserver setting in their e-mail
> client.
>> 3. Anyone who believes such to not be the case can attempt to telnet
>> into the SMTP server and see what happens.
> So far, I believe you. :-)
>> If [as I suspect] you can't
>> even get close using just "go-concepts.com," and you are bound and
>> determined to prove me wrong, please ask for the numeric address and I
>> will provide it. If you *can* manage to break in, then my ISP would
>> like to know that, and they won't get angry at you unless you also
>> decide to send out a spew of spam.
> I don't think it's a question of trying to prove anyone wrong, but of
> trying to learn something. So, as long as port 25 is not blocked on my
> network, surely, I should be able to telnet to one or more smtpservers
> at go-concepts.com that will accept mail for you or anyone else at
> go-concepts.com. Otherwise, how could anyone send you e-mail? Let's try
> a couple.
> (note - ESTMP without AUTH)
> # telnet go-concepts.com 25
> Trying 207.40.122.20 ...
> Connected to go-concepts.com.
> Escape character is '^]'.
> 220 ns1.go-concepts.com ESMTP Sendmail 8.11.0/8.11.0;
> Tue, 6 Feb 2001 01:11:35 -0500
> EHLO nyx10.nyx.net
> 250-ns1.go-concepts.com Hello [EMAIL PROTECTED] [206.124.29.2],
> pleased to meet you
> 250-ENHANCEDSTATUSCODES
> 250-8BITMIME
> 250-SIZE 7000000
> 250-DSN
> 250-ONEX
> 250-ETRN
> 250-XUSR
> 250 HELP
> mail from:<[EMAIL PROTECTED]>
> 250 2.1.0 <[EMAIL PROTECTED]>... Sender ok
> rcpt to:<[EMAIL PROTECTED]>
> 250 2.1.5 <[EMAIL PROTECTED]>... Recipient ok
> quit
> 221 2.0.0 ns1.go-concepts.com closing connection
> Connection closed by foreign host.
> #
�As I told someone else, this isn't exactly what was proposed but it is
> (note - ESTMP with AUTH)
> #telnet mail1.go-concepts.com
> Trying 207.40.122.7 ...
> Connected to mail1.go-concepts.com.
> Escape character is '^]'.
> 220 mail1.go-concepts.com ESMTP Sendmail 8.11.1/8.11.1;
> Tue, 6 Feb 2001 00:13:03 -0500
> EHLO nyx10.nyx.net
> 250-mail1.go-concepts.com Hello nyx10.nyx.net [206.124.29.2],
> pleased to meet you
> 250-ENHANCEDSTATUSCODES
> 250-8BITMIME
> 250-SIZE 7000000
> 250-DSN
> 250-ONEX
> 250-ETRN
> 250-XUSR
> 250-AUTH DIGEST-MD5 CRAM-MD5
> 250 HELP
> mail from:<[EMAIL PROTECTED]>
> 250 2.1.0 <[EMAIL PROTECTED]>... Sender ok
> rcpt to:<[EMAIL PROTECTED]>
> 250 2.1.5 <[EMAIL PROTECTED]>... Recipient ok
> quit
> 221 2.0.0 mail1.go-concepts.com closing connection
> Connection closed by foreign host.
> #
> Of course, I cannot use your ISP's mailservers to send mail to
> third-parties, but this is always the case with closed relays
> whether or not you have a password or some other method to do
> so. Here's an example.
> (note - Relaying denied without AUTH)
> #telnet go-concepts.com 25
> Trying 207.40.122.20 ...
> Connected to go-concepts.com.
> Escape character is '^]'.
> 220 ns1.go-concepts.com ESMTP Sendmail 8.11.0/8.11.0;
> Tue, 6 Feb 2001 02:20:23 -0500
> ehlo nyx10.nyx.net
> 250-ns1.go-concepts.com Hello [EMAIL PROTECTED] [206.124.29.2],
> pleased to meet you
> 250-ENHANCEDSTATUSCODES
> 250-8BITMIME
> 250-SIZE 7000000
> 250-DSN
> 250-ONEX
> 250-ETRN
> 250-XUSR
> 250 HELP
> mail from:<[EMAIL PROTECTED]>
> 250 2.1.0 <[EMAIL PROTECTED]>... Sender ok
> rcpt to:<[EMAIL PROTECTED]>
> 550 5.7.1 <[EMAIL PROTECTED]>... Relaying denied
> quit
> 221 2.0.0 ns1.go-concepts.com closing connection
> Connection closed by foreign host.
> #
> By the way, I normally use my ISP's smarthost (plain old-fashioned
> IP-based closed relay) to send e-mail, but since this discussion
> came up, I've been using POP-before-SMTP at gmx.net (a free e-mail
> service) with my DOS mailers.
> Howard E.
> --
> DOS TCP/IP * <URL:http://www.ncf.ca/~ag221/dosppp.html>
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