equivalent of /dev/null for emails? invalid.invalid?
Rahul
across it previously in a newsgroup posting about "address munging" and
have been ever since using nos...@invalid.invalid as my return email id on
newsgroups. (Related link: http://www.2kevin.net/munging.html#invalid)
While testing nagios on my linux box I temporarily wanted to disable
getting any emails so had this smart [sic] idea of using
"nos...@invalid.invalid" address in the nagios settings file.
Why yet does my MTA insist on adding entries of the sort: "Host unknown
(Name server: invalid.invalid: host not found)" in /var/mail/nagios every
time it was sent an email via nagios?
Or is this not a "real" convention!
Is there any equivalent of /dev/null for email?! An email blackhole?!
[not setting an email address within nagios wasn't an option; otherwise
nagios keeps insisting that I "forgot" to set any contactgroups!]
--
Rahul
Bit Twister
> Is the "invalid.invalid" a universally recognized convention?
See http://www.rfc-editor.org/rfc/rfc2606.txt section
2. TLDs for Testing, & Documentation Examples
>
> Why yet does my MTA insist on adding entries of the sort: "Host unknown
> (Name server: invalid.invalid: host not found)" in /var/mail/nagios every
> time it was sent an email via nagios?
Guessing you have not given your node a Fully Qualified Domain Name (FQDN)
or have not set a value in some configuration file.
I ran with a domain of home.invalid until I found out leafnode did not
like .invalid.
Current settings on my Mandriva Linux install follow:
$ hostname --fqdn
wm81.home.test
$ hostname --domain
home.test
$ grep $(hostname) /etc/hosts
192.168.1.131 wm81.home.test wm81
For setting FQDN on boot in Mandriva Linux and Redhat/fedora
$ grep $(hostname) /etc/sysconfig/network
HOSTNAME=wm81.home.test
Florian Diesch
> Is the "invalid.invalid" a universally recognized convention? I had come
.invalid is a reserved top level domain that is sure to be invalid,
see RFC 2606.
> Why yet does my MTA insist on adding entries of the sort: "Host unknown
> (Name server: invalid.invalid: host not found)" in /var/mail/nagios every
> time it was sent an email via nagios?
The host name can't be resolved (because it is invalid) and the MTA
complains about that.
> Or is this not a "real" convention!
>
> Is there any equivalent of /dev/null for email?! An email blackhole?!
There is no standard or convention for this. You can configure your
MTA to do such a thing or use a service like http://www.spamgourmet.com/.
Florian
--
<http://www.florian-diesch.de/>
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Maxwell Lol
> Is the "invalid.invalid" a universally recognized convention? I had come
> across it previously in a newsgroup posting about "address munging" and
> have been ever since using nos...@invalid.invalid as my return email id on
> newsgroups. (Related link: http://www.2kevin.net/munging.html#invalid)
As Bit Twister says
You can also use
example.com
example.net
example.org
Bit Twister
Bit Twister does /not/ say you can use example.(com,net,org).
Those are registered domains. .test and .invalid Top Level Domains are not.
For a unregistered domain, I would suggest/say to use .invalid and/or .test.
Internet mail server admins can/have put filters on their systems to
automatically drop test/invalid domains.
Rahul
@mid.florian-diesch.de:
> The host name can't be resolved (because it is invalid) and the MTA
> complains about that.
I see. I assumed since it was in the RFC most "mature" programs would be
trained to somehow "know" better than to try and resolve a .invalid domain.
>> Is there any equivalent of /dev/null for email?! An email blackhole?!
>
> There is no standard or convention for this. You can configure your
> MTA to do such a thing or use a service like http://www.spamgourmet.com/.
I think I'll configure my MTA sendmail (its a beast each time!). The
problem with the spamgourmet solution is that it still means sending those
emails out on the external network when all I want is them to be piped down
the "trash" chute. To a dark dark place. Like /dev/null/
Not that it would matter usually for bandwidth etc. but just a thought.
--
Rahul
David W. Hodgins
> Bit Twister does /not/ say you can use example.(com,net,org).
The standard is described in
http://www.rfc-editor.org/rfc/rfc2606.txt
which states you can use .test, .example, .invalid, .localhost, example.com, example.net,
and example.org
> Those are registered domains. .test and .invalid Top Level Domains are not.
They are registered by IANA, for use as per the rfc.
For the registered (by IANA) host names, they point to 208.77.188.166, which is
owned by ICANN.
Whatever you choose to use, I suggest using your own name server to provide,
or override, the ip address, to something you control.
Regards, Dave Hodgins
--
Change nomail.afraid.org to ody.ca to reply by email.
(nomail.afraid.org has been set up specifically for
use in usenet. Feel free to use it yourself.)
Rahul
news:op.upav3df...@hodgins.homeip.net:
> Whatever you choose to use, I suggest using your own name server to
> provide, or override, the ip address, to something you control.
>
Thanks David. Can I put that in my /etc/hosts?
I'm not sure how one does this actually! Is there a "REJECT" target?
Most lines I know are of the form."192.168.1.10 foo.mydomain.org foo"
How can I tell my system:
"REJECT *.invalid'
The man for "hosts" wasn't much help! Or can I hack this into resolv.conf?
How do you guys handle these special domains from the RFC?
--
Rahul
David W. Hodgins
> Thanks David. Can I put that in my /etc/hosts?
Sure, provided /etc/nsswitch.conf includes files in the hosts line, but
I don't think that will do what you want, as I think the mta will bypass
the hosts file, and insist on doing a dns lookup to validate the fqdn
of the host.
As the mta carries out a conversation with the recipient, simply routing
it to a non-existent ip address, or one that isn't ready to receive messages,
will produce error messages. The mta will insist on sending the message
somewhere, or will reject the message, as undeliverable.
> The man for "hosts" wasn't much help! Or can I hack this into resolv.conf?
> How do you guys handle these special domains from the RFC?
I don't use the special domains.
I run my own name server. I use a real domain name, that I've registered
with dyndns.org, for my computer (with the wildcard option, so I can use
subdomains), and one that I registered with freedns.org for my munged
usenet email address.
While computers outside of my system will use the name servers at dyndns
to find my public ip address, my system will use my name server, to get
the lan ip address.
Anyone sending email to my usenet from address, without making the
changes in my sig, will be sending email to a spamtrap.
If you simply want to ensure all incoming mail is held by the sending
mta, during your testing, I'd just block incoming packets to port 25.
Florian Diesch
> Florian Diesch <die...@spamfence.net> wrote in news:se4g66-9h9.ln1
> @mid.florian-diesch.de:
>
>> The host name can't be resolved (because it is invalid) and the MTA
>> complains about that.
>
> I see. I assumed since it was in the RFC most "mature" programs would be
> trained to somehow "know" better than to try and resolve a .invalid domain.
As one may use them to test the handling of invalid domains they
should be handled like invalid domains.
>>> Is there any equivalent of /dev/null for email?! An email blackhole?!
>>
>> There is no standard or convention for this. You can configure your
>> MTA to do such a thing or use a service like http://www.spamgourmet.com/.
>
> I think I'll configure my MTA sendmail (its a beast each time!).
AFAIK sendmail allows file delivery in /etc/aliases so you can just
deliver to /dev/null
Maxwell Lol
> I think I'll configure my MTA sendmail (its a beast each time!). The
> problem with the spamgourmet solution is that it still means sending those
> emails out on the external network when all I want is them to be piped down
> the "trash" chute. To a dark dark place. Like /dev/null/
If you receive a complete spam message, the damage to your bandwidth
is already done.
Just don't accept mail from people with invalid From: values.
Some tips are here.
http://www.sendmail.org/support/antispam/sf_highlight/spam
I use some DNS blocklists.
I also use a milter to block all spam from sites with invalid HELO
values. That eliminated about 40% of the spam. (I don't have to
worry about misconfigured clients).
Georg Horn
> I think I'll configure my MTA sendmail (its a beast each time!). The
> problem with the spamgourmet solution is that it still means sending those
> emails out on the external network when all I want is them to be piped down
> the "trash" chute. To a dark dark place. Like /dev/null/
Send these mails to something like null@localhost and add this line to
/etc/mail aliases (and of course rebuild aliases.db):
null: /dev/null
Bye,
Georg