[Dovecot] replicator/dsync over tcp

[Michael Grimm]

Timo Sirainen <tss at iki.fi> wrote:
> On 24.3.2013, at 23.07, Michael Grimm <trashcan at odo.in-berlin.de> wrote:

> 
>> First of all I did need to extend http://wiki2.dovecot.org/Replication to get dsync over tcp running without ssl:
> ..
>> | dovecot: doveadm(test): Error: doveadm_password not set, can't authenticate to remote server
> 
> Updated http://master.wiki2.dovecot.org/Replication with it.

My point has been, that I needed to add ...

| local 1.2.3.4 {
|         doveadm_password = secret
| }

... besides ...

| service doveadm {
|         inet_listener {
|                 address = 1.2.3.4
|                 port = 12345
|         }
| }

... which I cannot find at http://master.wiki2.dovecot.org/Replication if I am not mistaken.

>> 1. Question: may one include "secret" from a file?
> 
> name = </path/file works for all settings.

Thanks, applied and working.


>> Now, I did try to add ssl by activating "ssl = yes" in 'service doveadm' (see above) and adding ...
>> 
>> | # used by replicator/dsync over tcp
>> | #
>> | ssl_client_ca_dir = /<path-to>/ssl/certs
>> 
>> ... and ...
>> 
>> | mail_replica = tcps:SERVER-A.TLD
>> 
>> But, this didn't work (logfile at remote server):
>> 
>> | dovecot: doveadm(test): Invalid certificate: self signed certificate: /OU=dovecot server/CN=OTHER-NAME.TLD/emailAddress=postmaster at OTHER-NAME.TLD
>> | dovecot: doveadm(test): Error: SERVER-A.TLD: Received invalid SSL certificate
>> | dovecot: doveadm(test): Error: sync: Disconnected from remote
>> 
>> The OTHER-NAME.TLD is served by my additional settings used by my MUAs:
>> 
>> | ssl_cert = </<path-to>/ssl/certs/OTHER-NAME.TLD.pem
>> | ssl_key = </<path-to>/ssl/private/OTHER-NAME.TLD.pem
>> 
>> I did supply SERVER-A.TLD certs and private certificates at both servers as well, but dovecot seems to use those of OTHER-NAME.TLD for replicator/dsync instead :-(
> 
> The SERVER-A.TLD needs to have a certificate that is signed by one of the CAs in ssl_client_ca_dir. ssl_cert/key settings are irrelevant here. You can't use a self-signed cert, unless you put it into the CA dir (I don't know how exactly that works).

I did get tcps running in the meantime following:

1. http://www.zytrax.com/tech/survival/ssl.html ("Method 3" plus "Multi-Server Certificates")
2. postfix' documentation at http://www.postfix.org/TLS_README.html#server_cert_key (here I had to reverse order, meaning CA first)
3. pointing ssl_cert, ssl_key to relevant files in /<path-to>/ssl/ca/certs and /<path-to>/ssl/ca/private, respectively
4. ssl_client_ca_dir = /<path-to>/ssl/ca/certs


Question: Why is it neccessary to use ssl_cert/key settings from my CA although you state:
> ssl_cert/key settings are irrelevant here.


Besides dovecot is synchronising as expected, I do get a lot of logfile entries like ...

| dovecot: dsync-local(test): Warning: I/O leak: 0x10b8cf20 (line 341, fd 14)

... and in addition if "verbose_ssl = yes" is set:

| dsync-remote(test): Warning: SSL alert: where=0x4004, ret=256: warning close notify


Hmm, I do have to admit that I do not understand SSL/TLS/CA/...! 

Thus, I am uncertain whether to ignore those warnings or if my setup is broken in the first place?

All hints are highly appreciated,
Michael