Re: [SLE] SMTP authentication

Carlos E. R. wrote:
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The Saturday 2006-04-29 at 13:57 +0200, Hylton Conacher (ZR1HPC) wrote:


...

Sandy, the above paragraphs were pivotal to my understanding. Free beer/fruit
juice on the house for Sandy.

I have saved that email ;-)

You're welcome. If it saves you the pain having to type it all again when you need it to explain it to someone else you are welcome to recycle it. (^-^)

So eventhough my local SMTP server dials up to the internet with a certain
username and password, that same username and password would not be used as
authentication between my local SMTP server and the ISP's one, should it be
used as a relay?

No, your postfix uses the file "/etc/postfix/sasl_passwd" to decide what login/passwd to use. It contains lines like this:

mailhost.your.isp loginame:password

it means that, when talking to smtp server at "mailhost.your.isp", it must use the login/pass pair to the right. ISPs normally use the same password for everything (login, pop3, smtp, ftp...) just to save work.

Notice that if we had several users with accounts at that site, we would have problems... it is a server side configuration, not a users' configuration.

If you are using the snapshot version of Postfix (version 2.3) then you can use sender-dependent password authentication.

http://www.postfix.org/postconf.5.html#sender_dependent_relayhost_maps



The easiest way to test it is to set up several mail accounts in your
mailclient and configure each account to send with the same user/pass to
your ISP mailserver.
Sorry, I didn't see that I was able to specify the name and password the new
SMTP server I had added. :()

Mozilla will ask for the login/pass with a dialog at the moment it connects and sees they are needed.

I've added a new entry for smtp.gmail.com and used my gmail username to
authenticate. It didn't request a password so I assume that will come up when
I send the message.

Right.

The settings to use for gmail in mozilla are:

Server name: smtp.gmail.com port: 587

[X] Use name and password

User name: your_address@xxxxxxxxx

Use secure connection:

[ ] No [ ] TLS, if available [X] TLS [ ] SSL

Notice that the port number is selected automatically when selecting TLS - I think, it has being months since I configured this.

Port 587 is the submission port. It is mainly used for mail clients that need to authenticate before they can send mails. That port is normally configured to support TLS, use authentication and reject all clients that have not authenticated.
Sometimes it is the only way to use a mailserver different from the ISP mailserver when the ISP has blocked port 25 to suppress zombie spams to force clients to use the ISP mailserver.

Sandy

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