Re: Telnet sessions allowing spoofed e-mails

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

I can be more specific about our exchange server. We receive mail
fine to our exchange server at mail.company.com, but I cannot if I try
to open a telnet connection to mail.company.com on prot 25 then
telnet tells me that it cannot open a connection to port 25 on
mail.company.com. (The same thing happens if I don't specify a port,
except that if I don't specify a port then telnet tells me that it
cannot open a connection on port 23.)

I haven't looked into it yet, but is it possible that our firewall is
allowing SMTP traffic to the IP address of our exchange server, but
that it is not allowing telnet traffic to the IP address of that same
server?


On Thu, 8 Feb 2007 14:17:34 -0800, "John D. Gwinner"
<jgwinneratdazsidotcom@xxxxxxxxxxxx> wrote:

It would ... and it wouldn't, let's be specific.

If you disable the ability to telnet to port 25 on the mail server, you
won't be able to get outside mail. This is true.

If you disable the ability to telnet to the mail server without specifying a
port (port 23), then that won't have anything to do with outside mail.

== John ==

"ya_daddy" <yadaddy@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:0CEADC54-61D9-4C18-9F85-DA97B2194691@xxxxxxxxxxxxxxxx
So disabling Telnet won't cause an issue with outside e-mail being
received.
That's what I thought but I needed to know.

"Mark Arnold [MVP]" wrote:

On Thu, 8 Feb 2007 12:02:00 -0800, ya_daddy
<yadaddy@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

There's a misunderstanding here. You're not using telnet in the
conventional sense in that you're specifying 25 rather than 23. So you
shouldn't even have a telnet server on the Exchange server anyway.


.

Relevant Pages

  • Re: cannot telnet to port 25
    ... IMAP use port 143 to receive and send on port 25 using SMTP. ... Your problem is DNS related. ... Since you can telnet from outside but not from ... You can also use NSLOOKUP to verify the resolution of your Exchange server ...
    (microsoft.public.exchange.admin)
  • Problem with connecting by telnet to port 25
    ... not sure if this is the correct group so let me know. ... I service an Exchange Server which is working ... telnet port 25 i get this error "Connecting To localhost...Could not ... I can telnet to localhost port 110 without any problem and other can ...
    (microsoft.public.exchange.misc)
  • Re: Should add that ...
    ... turns out wasn't forwarding port 25. ... > Can you telnet to the servers internal nic from a WS on 25 ie Telnet ... >> GaryK ... >>> email, but if your Exchange server is offline, it holds the email until ...
    (microsoft.public.windows.server.sbs)
  • Re: not receiving external mail
    ... What I came to notice is that my home isp has port 25 completely blocked. ... When i had them try to telnet to me ... Does your Exchange server accept mail directly from the internet ... through the firewall or is there a SMTP gateway between the Exchange ...
    (microsoft.public.exchange.admin)
  • Re: SBS 2008 - Cant recieve mail
    ... It is setup with one Exchange server. ... I set up the Single Port Forwarding as follows: ... are you familiar with how to use telnet to check if you Exchange ... Did you setup an Edge or is SBS2008 setup with one Exchange server? ...
    (microsoft.public.windows.server.sbs)