Closed tehXor closed 5 years ago
I have seen this happening with a wrong MTU.
Am 16.01.2019 um 01:53 schrieb Till notifications@github.com:
Recently i'm getting Cannot start TLS: handshake failure for gmx.de and web.de recipients. Other provider like GMail work. However there are a lot of mails to GMX and web.de apperently.
Now I'm not sure if the problem lies on my end, within mailcow or GMX/web.de and the first question is, what's the best way to debug this problem in the containers? All I get from the logs is this:
1/16/2019, 1:31:28 AM | info | SSL_connect error to mx01.emig.gmx.net[212.227.17.5]:25: Connection timed out 1/16/2019, 1:31:28 AM | info | 8BE0C60724: Cannot start TLS: handshake failure 1/16/2019, 1:31:28 AM | info | SSL_connect error to mx00.emig.gmx.net[212.227.15.9]:25: Connection timed out 1/16/2019, 1:31:28 AM | info | B980C60729: Cannot start TLS: handshake failure 1/16/2019, 1:31:27 AM | info | SSL_connect error to mx-ha02.web.de[212.227.17.8]:25: Connection timed out 1/16/2019, 1:31:27 AM | info | 5EDA56072C: Cannot start TLS: handshake failure ...only a lot more.
Since I saw a timeout I already started by installing inetutils in the postfix container to check if it basically can connect to the hosts in question and that works. So it probably really is some specific SSL/TLS problem.
The problem started with a version which was around 4 weeks ago (but the problem itself came up just recently). I now upgraded to the recent master branch and regarding SSL/TLS my postfix configuration is basically the same as in master. This problem still persists though.
Any hint to better debug this or temporally workaround (even if unsecure) would be welcome. Thanks!
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Very helpful tip @andryyy thanks a lot - and this made all further troubleshooting invalid since exactly that was the problem. Our VMs got moved to a new virtual network with a MTU of 1400 two days ago...
The fast solution is adding com.docker.network.driver.mtu
to the docker-compose file so that the first part of the network looks like this:
networks:
mailcow-network:
driver: bridge
driver_opts:
com.docker.network.driver.mtu: 1400
In our case we will now also check if there are better global options, which doesn't involve updatating the docker-compose files of every project. Should we find one, I will add it here.
Nice! :)
Same error here and the hint with mtu does not work for me any idea?
part of my docker-compose.yml:
...
...
networks:
mailcow-network:
driver: bridge
driver_opts:
com.docker.network.driver.mtu: 1400
enable_ipv6: true
ipam:
driver: default
config:
- subnet: ${IPV4_NETWORK:-172.22.1}.0/24
- subnet: ${IPV6_NETWORK:-fd4d:6169:6c63:6f77::/64}
Undelivered Mail Returned to Sender Message:
This is the mail system at host mx.foobar.com.
I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
The mail system
<webmaster@xmail.com>: Cannot start TLS: handshake failure
Reporting-MTA: dns; mx.foobar.com
X-Postcow-Queue-ID: BC4BB880F59
X-Postcow-Sender: rfc822; billing@host.com
Arrival-Date: Thu, 21 Mar 2019 13:23:53 +0100 (CET)
Final-Recipient: rfc822; webmaster@xmail.com
Original-Recipient: rfc822;webmaster@xmail.com
Action: failed
Status: 5.7.5
Diagnostic-Code: X-Postcow; Cannot start TLS: handshake failure
Von: Billing Service <billing@host.com>
Betreff: Ihre Rechnung
Datum: 21. März 2019 um 13:23:46 MEZ
An: Customer Name <webmaster@xmail.com>
Why do you think this is a MTU issue exactly? Just want to be sure. What is your default MTU on the primary NIC?
root@mx ~/dev/mailcow-dockerized # ifconfig eth0|grep mtu
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
I've also tried 1500 but it does also not work :(
Please don't change the stacks MTU if you don't have to.
It is just a TLS handshake failure then. Check if that happens with other servers, too. Perhaps you enforce TLS for this mailbox and the remote servers protocol/ciphers are just too old.
It does not affect all remote mailboxes most functioning but there are some that have problems. I had just read the headline "Cannort start TLS" and thought that it might have been there.
Where on my side could I accept that? (old protocol/ciphers) or where can I force TLS for a remote mailbox/domain?
You should debug if that’s the problem after all.
You could try to connect with OpenSSL on these ports. Also login to that mailbox via mailcow UI and see if it has encryption enforced. It would fall back to a plain session if encryption fails and no encryption was enforced.
If it’s an incoming mail problem, check the certificate! If you use an external acme client, you might have missed to copy the renewed certificate.
Hi Andre i got this:
root@mx ~/dev/mailcow-dockerized # openssl s_client -showcerts -connect mx-in.planet-school.de:587
139631594094656:error:0200206F:system library:connect:Connection refused:../crypto/bio/b_sock2.c:108:
139631594094656:error:2008A067:BIO routines:BIO_connect:connect error:../crypto/bio/b_sock2.c:109:
connect:errno=111
root@mx ~/dev/mailcow-dockerized # openssl s_client -showcerts -connect mx-in.planet-school.de:993
140718373584960:error:0200206F:system library:connect:Connection refused:../crypto/bio/b_sock2.c:108:
140718373584960:error:2008A067:BIO routines:BIO_connect:connect error:../crypto/bio/b_sock2.c:109:
connect:errno=111
root@mx ~/dev/mailcow-dockerized # openssl s_client -showcerts -connect mx-in.planet-school.de:995
140515483316288:error:0200206F:system library:connect:Connection refused:../crypto/bio/b_sock2.c:108:
140515483316288:error:2008A067:BIO routines:BIO_connect:connect error:../crypto/bio/b_sock2.c:109:
connect:errno=111
root@mx ~/dev/mailcow-dockerized # openssl s_client -showcerts -connect mx-in.planet-school.de:25
CONNECTED(00000003)
139647800877120:error:1408F10B:SSL routines:ssl3_get_record:wrong version number:../ssl/record/ssl3_record.c:252:
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 5 bytes and written 176 bytes
Verification: OK
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
Protocol : TLSv1.2
Cipher : 0000
Session-ID:
Session-ID-ctx:
Master-Key:
PSK identity: None
PSK identity hint: None
SRP username: None
Start Time: 1553194492
Timeout : 7200 (sec)
Verify return code: 0 (ok)
Extended master secret: no
---
and
root@mx ~/dev/mailcow-dockerized # openssl s_client -showcerts -connect mx-in.planet-school.de:465
CONNECTED(00000003)
depth=2 C = BE, O = GlobalSign nv-sa, OU = Root CA, CN = GlobalSign Root CA
verify return:1
depth=1 C = BE, O = GlobalSign nv-sa, CN = AlphaSSL CA - SHA256 - G2
verify return:1
depth=0 OU = Domain Control Validated, CN = *.planet-school.de
verify return:1
---
Certificate chain
0 s:/OU=Domain Control Validated/CN=*.planet-school.de
i:/C=BE/O=GlobalSign nv-sa/CN=AlphaSSL CA - SHA256 - G2
-----BEGIN CERTIFICATE-----
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42cZpPyn
-----END CERTIFICATE-----
1 s:/C=BE/O=GlobalSign nv-sa/CN=AlphaSSL CA - SHA256 - G2
i:/C=BE/O=GlobalSign nv-sa/OU=Root CA/CN=GlobalSign Root CA
-----BEGIN CERTIFICATE-----
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-----END CERTIFICATE-----
---
Server certificate
subject=/OU=Domain Control Validated/CN=*.planet-school.de
issuer=/C=BE/O=GlobalSign nv-sa/CN=AlphaSSL CA - SHA256 - G2
---
No client certificate CA names sent
Server Temp Key: DH, 1024 bits
---
SSL handshake has read 3992 bytes and written 374 bytes
Verification: OK
---
New, SSLv3, Cipher is DHE-RSA-AES256-SHA
Server public key is 4096 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
Protocol : TLSv1
Cipher : DHE-RSA-AES256-SHA
Session-ID: 39519FA92ABE4C0C78038A97D0D9798A0F156527CEA5DDE1FC71A13E09691436
Session-ID-ctx:
Master-Key: 0196242022A3D232C47641F71403B773D76BE375A4D78DA1E63B832B959E0740CF3CC23A85AE889E0E16483DBCEB46E2
PSK identity: None
PSK identity hint: None
SRP username: None
TLS session ticket:
0000 - 5b 4d 2b 46 55 15 21 99-7c ba 08 76 a0 76 4d 45 [M+FU.!.|..v.vME
0010 - 8c 81 d5 73 e9 61 33 82-4f a9 91 8a 31 9f c6 57 ...s.a3.O...1..W
0020 - e0 d1 a9 2b c8 3c bc 88-b9 eb bd c1 11 d1 ce 2c ...+.<.........,
0030 - 54 9a f3 37 29 0e e4 25-1d 67 b9 e4 86 a8 bb 0d T..7)..%.g......
0040 - 68 24 ac 12 b6 40 d1 6c-e4 f3 1a 23 ca a5 20 33 h$...@.l...#.. 3
0050 - ba 2c 09 ea f7 74 c1 e2-ab cf d1 9f 96 68 a9 8e .,...t.......h..
0060 - 34 79 61 0d 90 e5 55 ef-fd 33 41 8d 8f 66 d0 09 4ya...U..3A..f..
0070 - 03 21 4f 2f 3e 82 5a d0-8d 86 27 2f 69 a2 51 44 .!O/>.Z...'/i.QD
0080 - 24 27 c5 af 0d 58 19 99-b6 fe d4 0e 93 d5 eb 27 $'...X.........'
0090 - a4 e6 33 c1 98 e5 44 03-81 d8 78 d3 80 89 ad 80 ..3...D...x.....
Start Time: 1553194623
Timeout : 7200 (sec)
Verify return code: 0 (ok)
Extended master secret: no
---
220 mx-in.planet-school.de ESMTP PS-MXCluster
is a bit confusing, here it works (same mail-to):
Mar 20 10:36:03 mx postfix/smtp[23597]: Anonymous TLS connection established to mx-in.planet-school.de[194.116.186.73]:25: TLSv1 with cipher ADH-AES256-SHA (256/256 bits)
Mar 20 10:36:03 mx postfix/smtp[23597]: 666A2880F1D: to=<webmaster@xmail.com>, orig_to=<redaktion@mailhost.de>, relay=mx-in.planet-school.de[194.116.186.73]:25, delay=1.3, delays=0.96/0.02/0.14/0.23, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as A6EA3804F8)
and same host different messages:
Mar 15 14:20:01 mx enforced-tls-smtp/smtp[23456]: SSL_connect error to mx-in.planet-school.de[194.116.186.73]:25: -1
Mar 15 14:20:01 mx enforced-tls-smtp/smtp[23456]: BA0CB881A81: to=<webmaster@xmail.com>, relay=mx-in.planet-school.de[194.116.186.73]:25, delay=0.28, delays=0.19/0.02/0.07/0, dsn=5.7.5, status=bounced (Cannot start TLS: handshake failure)
i also tried the web based client sogo and i got mailer returns... i don't know what it is but i've only had this problem since the last upgrade 1-2 weeks ago
enforced-tls-smtp/smtp
That’s exactly what I meant. We tightened the mandatory ciphers. You enforce TLS for that mailbox, so Postfix uses only secure protocols and ciphers and rejects if it cannot negotiate a secure channel.
I don’t plan to lower mandatory encryption levels, but you can change your own setup to accept less secure protocols and ciphers, if you need to. Alternatively disable enforced TLS.
Since this is outgoing mail, you can also create a TLS policy map in mailcow and override the TLS level requirement for that domain.
I know this is an older issue, but still stumbled over it.
How would a TLS map configuration look like in this case?
I am having issues with gmx.de
at the moment and tried to set up the policy in order to overwrite the otherwise enforced incoming and outgoing TLS requirements of the mailbox.
Below config did not work:
Any advise @andryyy ?
Recently i'm getting
Cannot start TLS: handshake failure
for gmx.de and web.de recipients. Other provider like GMail work. However there are a lot of mails to GMX and web.de apperently.Now I'm not sure if the problem lies on my end, within mailcow or GMX/web.de and the first question is, what's the best way to debug this problem in the containers? All I get from the logs is this:
...only a lot more.
Since I saw a timeout I already started by installing inetutils in the postfix container to check if it basically can connect to the hosts in question and that works. So it probably really is some specific SSL/TLS problem.
The problem started with a version which was around 4 weeks ago (but the problem itself came up just recently). I now upgraded to the recent master branch and regarding SSL/TLS my postfix configuration is basically the same as in
master
. This problem still persists though.Any hint to better debug this or temporally workaround (even if unsecure) would be welcome. Thanks!