[Dovecot] Difference between LOGIN and PLAIN

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[Dovecot] How can we horizontally...

Simon Brereton

3 Nov 2011 3 Nov '11

10:42 p.m.

Could someone explain to me the difference between LOGIN and PLAIN? I've been googling for a while, but haven't found anything.

Thanks.

Simon

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Patrick Ben Koetter

3 Nov 3 Nov

11 p.m.

Simon Brereton <simon.brereton@buongiorno.com>:

...

Could someone explain to me the difference between LOGIN and PLAIN?

In SMTP these are:

Both

are plaintext mechanisms.
base64 encode identification data before they send it over the wire
do not encrypt the indentification data and should therefore only be offered over an encrypted transport layer

PLAIN

is an open standard supported by most clients
sends identification data as one string
sends an authentication ID, an authorization ID and the password

is a proprietary standard supported by Microsofts clients
sends LOGIN, login name, password and optionally the domain name one after another

I guess they are basically the same in IMAP, but others will know better.

p@rick

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Stephan Bosch

11:01 p.m.

On 11/3/2011 9:42 PM, Simon Brereton wrote:

...

The LOGIN SASL mechanism is an obsolete plain text mechanism. It is documented here:

http://tools.ietf.org/html/draft-murchison-sasl-login-00

Some clients still support it, but I would not recommend using it when PLAIN or a better SASL mechanism is also available at both ends. The PLAIN mechanism is documented here:

http://tools.ietf.org/html/rfc4616

The main technical difference between the two is that the PLAIN mechanism transfers both username and password in a single SASL interaction, where LOGIN needs two. The PLAIN mechanism also provides support for having an authorization id different from the authentication id, allowing for master user login for example.

Regards,

Stephan.