[gentoo-user] Unable to locate mail

[gentoo-user] Unable to locate mail

[Michael Kintzios]

[-- Attachment #1: Type: text/plain, Size: 789 bytes --]

Hi All,

I have not (knowingly) set up my syslog-ng, logrotate, or some other application to send me mail, so I am curious where this little message came from:
=======================================
Feb 17 20:10:02 study1 cron[12102]: (root) CMD (test -x /usr/sbin/run-crons && /usr/sbin/run-crons )
Feb 17 20:11:58 study1 sSMTP[12061]: Unable to locate mail
Feb 17 20:11:58 study1 sSMTP[12061]: Cannot open mail:25
Feb 17 20:11:58 study1 cron[12047]: (root) MAIL (mailed 69 bytes of output but got status 0x0001 )
Feb 17 20:20:01 study1 cron[12132]: (root) CMD (test -x /usr/sbin/run-crons && /usr/sbin/run-crons )
Feb 17 20:30:01 study1 cron[12144]: (root) CMD (test -x /usr/sbin/run-crons && /usr/sbin/run-crons )
=======================================

Any ideas?
-- 
Regards,
Mick

Re: [gentoo-user] Unable to locate mail

[Christopher Cowart]

[-- Attachment #1: Type: text/plain, Size: 1600 bytes --]

If a cron generates any output while it's running, it tries to email it
to root@localhost.

ssmtp is your default MTA, and it's default configuration points to the
host mail, at port 25. As mail doesn't resolve to any mail server,
that's the sSMTP error you're seeing.

If you don't want cron mails, you can redirect ( > ) the output to a
file or /dev/null.

You could also configure sSMTP to have a reverse alias, so that when it
tries to e-mail root, it'll e-mail you@yourisp.com. This would involve
also changing sSMTP to be aware of your ISP's mail hub.

-Chris

On 20:58 Fri 17 Feb     , Michael Kintzios wrote:
> Hi All,
> 
> I have not (knowingly) set up my syslog-ng, logrotate, or some other application to send me mail, so I am curious where this little message came from:
> =======================================
> Feb 17 20:10:02 study1 cron[12102]: (root) CMD (test -x /usr/sbin/run-crons && /usr/sbin/run-crons )
> Feb 17 20:11:58 study1 sSMTP[12061]: Unable to locate mail
> Feb 17 20:11:58 study1 sSMTP[12061]: Cannot open mail:25
> Feb 17 20:11:58 study1 cron[12047]: (root) MAIL (mailed 69 bytes of output but got status 0x0001 )
> Feb 17 20:20:01 study1 cron[12132]: (root) CMD (test -x /usr/sbin/run-crons && /usr/sbin/run-crons )
> Feb 17 20:30:01 study1 cron[12144]: (root) CMD (test -x /usr/sbin/run-crons && /usr/sbin/run-crons )
> =======================================
> 
> Any ideas?
> -- 
> Regards,
> Mick
> 


-- 
Christopher Cowart
Unix Systems Administrator
Residential Computing, UC Berkeley
"May all your pushes be popped"

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

[gentoo-user] Re: Unable to locate mail

[Mick]

Christopher Cowart wrote:

> If a cron generates any output while it's running, it tries to email it
> to root@localhost.

Thanks Chris, I never understood this root@localhost (probably because I
have inadequate knowledge of many matters relating to mail within an OS). 
Where is root@localhost, where is mail for root@localhost stored, how is it
meant to be retrieved?

> ssmtp is your default MTA, and it's default configuration points to the
> host mail, at port 25. As mail doesn't resolve to any mail server,
> that's the sSMTP error you're seeing.

Is this meant to be a real (external) mail server e.g. smtp.my_isp.com, or
is there a Linux OS setup I can use internally without mail leaving the
box?

> You could also configure sSMTP to have a reverse alias, so that when it
> tries to e-mail root, it'll e-mail you@yourisp.com. This would involve
> also changing sSMTP to be aware of your ISP's mail hub.
. . . as in my ISP's smtp server?
-- 
Regards,
Mick

-- 
gentoo-user@gentoo.org mailing list

Re: [gentoo-user] Re: Unable to locate mail

[Christopher Cowart]

[-- Attachment #1: Type: text/plain, Size: 2200 bytes --]

 
> Thanks Chris, I never understood this root@localhost (probably because I
> have inadequate knowledge of many matters relating to mail within an OS). 
> Where is root@localhost, where is mail for root@localhost stored, how is it
> meant to be retrieved?
localhost means your box. Any network traffic destined for the localhost
goes through the "loopback device" and shows up right where it left.
localhost resolves to 127.0.0.1, as you'll notice in any default
/etc/hosts. If you have sshd running on a box, you can "ssh localhost".
If you have apache running, you could type in your browser
"http://localhost/". Using localhost works on Windows too...

Most importantly (to this discussion) ...
> Is this meant to be a real (external) mail server e.g. smtp.my_isp.com, or
> is there a Linux OS setup I can use internally without mail leaving the
> box?
If you have an MTA (Mail transfer agent) running on your box, you can
relay e-mail through your localhost. However, chances are you don't want
to run a full-blown MTA, not even to deliver root e-mails. These
programs would include postfix, exim, and sendmail. Although it can be
quite trivial to restrict traffic to your localhost, an MTA like postfix
is really overkill for a personal computer.

Instead, you can configure ssmtp to relay through somebody elses' SMTP
server. The problem is that if you e-mail something to "root@localhost",
but connect to smtp.yourisp.com, localhost still means "127.0.0.1,"
which as far as smtp.yourisp.com is concerned, is /their/ localhost, not
yours. Thus, you implement a reverse alias in /etc/ssmtp/revaliases.
That way, any outgoing mail destined for root, the headers can be
rewritten to have it sent to you@yourisp.com. 

So, if you're not running an smtp server on your localhost (and you
probably don't need to be... shouldn't be), you could relay through your
ISP. But, you may not want clear text about problems with your machine
flying around the internet... It does raise security concerns, but
you're probably ok to do it.

-Chris

-- 
Christopher Cowart
Unix Systems Administrator
Residential Computing, UC Berkeley
"May all your pushes be popped"

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

[gentoo-user] Re: Re: Unable to locate mail

[Mick]

Christopher Cowart wrote:

>  
>> Thanks Chris, I never understood this root@localhost (probably because I
>> have inadequate knowledge of many matters relating to mail within an OS).
>> Where is root@localhost, where is mail for root@localhost stored, how is
>> it meant to be retrieved?
> localhost means your box. Any network traffic destined for the localhost
> goes through the "loopback device" and shows up right where it left.
> localhost resolves to 127.0.0.1, as you'll notice in any default
> /etc/hosts. If you have sshd running on a box, you can "ssh localhost".
> If you have apache running, you could type in your browser
> "http://localhost/". Using localhost works on Windows too...
> 
> Most importantly (to this discussion) ...
>> Is this meant to be a real (external) mail server e.g. smtp.my_isp.com,
>> or is there a Linux OS setup I can use internally without mail leaving
>> the box?
> If you have an MTA (Mail transfer agent) running on your box, you can
> relay e-mail through your localhost. However, chances are you don't want
> to run a full-blown MTA, not even to deliver root e-mails. These
> programs would include postfix, exim, and sendmail. Although it can be
> quite trivial to restrict traffic to your localhost, an MTA like postfix
> is really overkill for a personal computer.

Indeed.

> Instead, you can configure ssmtp to relay through somebody elses' SMTP
> server. The problem is that if you e-mail something to "root@localhost",
> but connect to smtp.yourisp.com, localhost still means "127.0.0.1,"
> which as far as smtp.yourisp.com is concerned, is /their/ localhost, not
> yours. Thus, you implement a reverse alias in /etc/ssmtp/revaliases.
> That way, any outgoing mail destined for root, the headers can be
> rewritten to have it sent to you@yourisp.com.

Understood.

> So, if you're not running an smtp server on your localhost (and you
> probably don't need to be... shouldn't be), you could relay through your
> ISP. But, you may not want clear text about problems with your machine
> flying around the internet... It does raise security concerns, but
> you're probably ok to do it.

I am thinking that mailing is probably not required for my needs.  The
dead.letter file in /root should capture all these messages?

Thanks again a most clear explanation.
-- 
Regards,
Mick

-- 
gentoo-user@gentoo.org mailing list