I’m reluctant to post this here b/c I’m relatively certain this is an Android generated question and not a problem with K-9 which I’ve been using for around a decade.
For a lot of that decade I’ve been running my own email for my vanity domain with the mailboxes hosted on my home gateway device running some flavor of debian with dovecot. After the most recent upgrade of that gateway device, I discovered an issue with the self-signed certificate.
Background - the phone I’m currently using came out of the box with Android 11 and subsequently updated to 12. When I put this device into service I had no issue storing the self-signed certificate exception on Android 11. Now I simply get an error:
Setup could not finish
Cannot connect to server.
(Unable to execute POP3 command).
With the options of ‘continue’ and ‘edit details’.
Same version of K-9 on last phone I was using (no Android 12 support) gives the usual warning and prompt to end the session or store the exception.
I know this isn’t a K-9 issue, just curious if anyone else has experienced this. I wonder if something changed with SSLException handling depending on whether the phone has some kind of physical security (unlock code, etc.).
I know that I can ‘fix’ the problem by setting up certbot on the dovecot box, but I’m a bit paranoid that Letsencrypt might be a trap that I’d rather not get caught in. I suppose my other option is to create a CA and install it on the phone manually, but just looking for the path of least resistance.
I (mostly) fully understand the security risks presented by using self-signed certificates. I always initiate the certificate acceptance session over a private network which I control, so there’s little exposure to a mitm vector. I’m not securing state secrets either. I just want things to work like they used to for another 10 years. After that I won’t need email on my phone.
and you already know all the answers and have immutable secret opinions?
Dovecot, as you well know, is not a website and all email definitely needs TLS.
I don’t understand how you can see a painfully limited protocol like POP3 as more flexible than IMAP, and, honestly, I don’t particularly want to. POP3 is uniquely unsuitable for use with mailboxes used on more than one device. (I mention that not for your benefit, but rather that of the unsuspecting reader who has not yet discovered this firsthand.)
Kudos to you for the S at least.
Now you just need to work out whether or not to roll your own CA. I’ll risk another dismissed suggestion and offer my endorsement of XCA to use if you decide to go that route.
Whatever you settle on, I hope it works out for you, even though it’s definitely not the way I would do any of it.
Because I was looking for confirmation that handling SSLExceptions changed with an Android update.
It was meant to further demonstrate my unwillingness to do what everybody else is doing just because Google tells them they need to.
That’s your opinion, and I respect it. But I don’t necessarily agree with a blanket statement like that. There’s still an awful lot of email traversing the interwebs over port 25 unencrypted. It’s a lot like ipv4, it just won’t ever go away completely.
It’s not the protocol I find unflexible, it’s mainly the client side of the equation. I use email the way I use it, and keeping all my eggs on the server is not my preference. Much in the same way I prefer to drive cars that have thee pedals in the driver’s footwell - it’s not for everyone and I’m not suggesting it should be.
That’s neat, but I already have all the necessary tools available to me in /usr/bin/openssl. Why overcomplicate things with a GUI?
If you really insist on using POP3, I recommend looking for another email client, not K-9. You can’t export or move the emails from K-9, so if they are gone from the server and you want to switch phones, they’re gone.
I’m fully aware of that and it’s of zero importance to me. I store my email elsewhere. Having a client to read and on occasion reply with a baby computer (phone) is a convenience. When I want to do real things I use a grown up computer, with a keyboard that has real buttons.
[trying to move this forward - because i don’t see any imap/pop cause for this and there are many very valid reasons to use self-signed certs … ]
what shows in dovecot logging?
i’m using rhel/centos for my OS, so some things may be different, but in my:
configuration file there’s an option setting of:
#Show protocol level SSL errors. #verbose_ssl = no
the default, in my environment, is “no”. you might want to turn that to “yes” to see what it shows.
also, what release of K9 are you using - and did that change when you updated the device? i believe that there was a change in self-signed certificate handling in K9 a bit ago, don’t remember exactly when.
as a note, i have two android 14 devices, both on K9 6.711. one has been using my self-signed cert for some time. the other won’t accept it even when i tell it to at the prompt.
Finally someone who doesn’t drink the LE kool-aid!
The version currently on the play store - 6.603. I tried older versions going back to 5.x with the same results. This is why I suspect it’s an issue that was introduced by an API change.
This is what I get without verbose_ssl:
dovecot: pop3-login: Disconnected (no auth attempts in 0 secs): user=<>, rip=192.168.24.104, lip=x.x.x.x, TLS handshaking: SSL_accept() failed: error:14094416:SSL routines:ssl3_read_bytes:sslv3 alert certificate unknown: SSL alert number 46, session=<XXC6vm8KOrnAqBho>
I did try with verbose_ssl and it lead me to no better conclusion except the client is ending the TLS negotiation with reason 46.
I haven’t tried older versions of K-9 on the Android 11 device, but the same 6.603 gives the warning and stores the self-signed exception.
I’m accepting the fact that I just need to create a CA or use the one I’ve already created for openvpn and go on with life. I have no need for a phone that costs more than $100 so I don’t see Android > 12 coming my way any time soon.
I’m pretty sure I came across that mailing list discussion yesterday, but didn’t see the previous message. That’s a pretty elegant explanation of chaining to the uninitiated. This is a complex subject and I seem to only delve into it often enough to maintain a remedial understanding of it. Oh well, what doesn’t kill us only makes us stronger, right?
Whatever the case, this isn’t a chained cert, it happens with the simple snakeoil cert that’s auto-generated during debian os install. Though I typically re-generate it with a 4k keylength.
Nonetheless, thanks for the intelligent discussion.