[kwlug-disc] Testing a mail port

[Bob Jonkman]

The up-to-date RFC for e-mail is RFC5321, updated by RFC7504 for some
additional error codes.

https://tools.ietf.org/html/rfc5321
https://tools.ietf.org/html/rfc7504

Dense reading, but the final arbiter for the mail standard.

The IETF has a "Standards Track", where a particular standard, say SMTP,
is given a fixed number, STD10. The text in STD10 should be replaced as
the RFCs are updated. But the current STD10 document still contains RFC821:

https://tools.ietf.org/html/std10

This is probably because RFC2821 (now obsolete) never made it past
"Draft Standard", and RFC5321 is still a "Proposed Standard".


As far as a presentation for 'nc' and 'dig' go, there must be plenty of
people who don't know all the commands in /bin and /usr/bin - literally
thousands of them!  I wouldn't mind having an evening of ultra-short
demos of CLI commands.  Everyone who attends has a few minutes (5? 10?)
to show off their favorite command(s).  Duplication is perfectly OK,
since you might grep in a different way than I grep.  Live dangerously,
no set speaker roster, just whoever happens to be there.

--Bob, who just learned about the 'host' command today.


On 2016-03-11 11:16 AM, Khalid Baheyeldin wrote:
> For dig, you don't need a tutorial. It is just a fancier nslookup. The
> man pages suffice here.
> 
> Learning the underlying DNS/Whois is what matters (e.g. A record is
> for hosts IPv4, AAAA is IPv6, MX is mail servers, TXT is SPF, CNAME is
> host aliased to other hosts, ...etc.)
> 
> As for nc, it is a generic network tool. The Digital Oceans tutorial is good
> 
> https://www.digitalocean.com/community/tutorials/how-to-use-netcat-to-establish-and-test-tcp-and-udp-connections-on-a-vps
> 
> And some tricks here
> 
> http://www.thegeekstuff.com/2012/04/nc-command-examples/
> 
> You do not need nc for basic mail server troubleshooting since telnet
> does the same thing. Again, what is important is learning the
> underlying mail server protocol is what matters, not the tool that you
> will be sending those command from.
> 
> The RFC for SMTP is here
> http://www.ietf.org/rfc/rfc2821.txt
> 
> As usual with RFCs it is dense and terse.
> 
> The gist of it is here:
> 
> http://www.tutorialspoint.com/internet_technologies/e_mail_protocols.htm
> 
> Remember that this is for plain text, which has been the case for
> decades, but now many servers use encrypted connections, so not as
> easy to simulate using telnet/nc.
> 
> On Thu, Mar 10, 2016 at 8:38 AM, Joseph Wennechuk
> <youcanreachmehere at hotmail.com> wrote:
>> So through all of this I learned that I need to brush up on two commands
>> that seem very useful. I need to hone my skills with nc, and dig. They both
>> seem very useful. Has there been a presentation about these?
>>
>>
>> _______________________________________________
>> kwlug-disc mailing list
>> kwlug-disc at kwlug.org
>> http://kwlug.org/mailman/listinfo/kwlug-disc_kwlug.org
>>
> 
> 
> 

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