TLS problem with iOS 9 Mail clients
Hi everyone,
recently I migrated my mail server from an Ubuntu 16.04 box to an Ubuntu 20.04 box, so from dovecot 2.2.22 to 2.3.7.2, and to openssl 1.1.1.f. While everything else works fine, I have one important user stuck on an iOS 9 device that I need to support for a while longer, with which the IMAP TLS handshake keeps failing. From the logs:
TLS handshaking: SSL_accept() failed: error:14209102:SSL routines:tls_early_post_process_client_hello:unsupported protocolI didn’t find a debug option to dump the TLS handshake details, so I analyzed a packet dump and found the following capabilities and cipher suites offered by the client:
Transport Layer Security TLSv1 Record Layer: Handshake Protocol: Client Hello Content Type: Handshake (22) Version: TLS 1.0 (0x0301) Length: 149 Handshake Protocol: Client Hello Handshake Type: Client Hello (1) Length: 145 Version: TLS 1.0 (0x0301) Random: 5fef787ac06215d0a4edefd17602fadf409ab0512e04e62ade6192f2499f4896 Session ID Length: 0 Cipher Suites Length: 50 Cipher Suites (25 suites) Cipher Suite: TLS_EMPTY_RENEGOTIATION_INFO_SCSV (0x00ff) Cipher Suite: TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 (0xc024) Cipher Suite: TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 (0xc023) Cipher Suite: TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA (0xc00a) Cipher Suite: TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA (0xc009) Cipher Suite: TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA (0xc008) Cipher Suite: TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (0xc028) Cipher Suite: TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (0xc027) Cipher Suite: TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (0xc014) Cipher Suite: TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (0xc013) Cipher Suite: TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA (0xc012) Cipher Suite: TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 (0x006b) Cipher Suite: TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 (0x0067) Cipher Suite: TLS_DHE_RSA_WITH_AES_256_CBC_SHA (0x0039) Cipher Suite: TLS_DHE_RSA_WITH_AES_128_CBC_SHA (0x0033) Cipher Suite: TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA (0x0016) Cipher Suite: TLS_RSA_WITH_AES_256_CBC_SHA256 (0x003d) Cipher Suite: TLS_RSA_WITH_AES_128_CBC_SHA256 (0x003c) Cipher Suite: TLS_RSA_WITH_AES_256_CBC_SHA (0x0035) Cipher Suite: TLS_RSA_WITH_AES_128_CBC_SHA (0x002f) Cipher Suite: TLS_RSA_WITH_3DES_EDE_CBC_SHA (0x000a) Cipher Suite: TLS_ECDHE_ECDSA_WITH_RC4_128_SHA (0xc007) Cipher Suite: TLS_ECDHE_RSA_WITH_RC4_128_SHA (0xc011) Cipher Suite: TLS_RSA_WITH_RC4_128_SHA (0x0005) Cipher Suite: TLS_RSA_WITH_RC4_128_MD5 (0x0004) Compression Methods Length: 1 Compression Methods (1 method) Compression Method: null (0) Extensions Length: 54 Extension: server_name (len=19) Type: server_name (0) Length: 19 Server Name Indication extension Extension: supported_groups (len=8) Extension: ec_point_formats (len=2) Type: ec_point_formats (11) Length: 2 EC point formats Length: 1 Elliptic curves point formats (1) EC point format: uncompressed (0) Extension: status_request (len=5) Type: status_request (5) Length: 5 Certificate Status Type: OCSP (1) Responder ID list Length: 0 Request Extensions Length: 0 Extension: signed_certificate_timestamp (len=0) Type: signed_certificate_timestamp (18) Length: 0
I already tweaked the dovecot-ssl config down with "ssl_min_protocol = TLSv1” and included ECDHE-ECDSA-AES256-SHA in the cipher list, but the client still won’t connect.
Does anyone have an idea what else I could try?
Thanks Maik
On 01 Jan 2021, at 16:01, Maik Musall lists@musall.de wrote:
recently I migrated my mail server from an Ubuntu 16.04 box to an Ubuntu 20.04 box, so from dovecot 2.2.22 to 2.3.7.2, and to openssl 1.1.1.f. While everything else works fine, I have one important user stuck on an iOS 9 device that I need to support for a while longer, with which the IMAP TLS handshake keeps failing. From the logs:
macOS 9 does not support any currently valid and support TLS version and cannot communicate on the Internet securely.
Does anyone have an idea what else I could try?
Have them get an iPad for mail? I don't think they can even use secure webmail.
-- All he [Vimes] knew was that you couldn't hope to try for the big stuff, like world peace and happiness, but you might just about be able to achieve some tiny deed that'd make the world, in a small way, a better place. Like shooting someone.
Am 02.01.2021 um 01:42 schrieb @lbutlr kremels@kreme.com:
On 01 Jan 2021, at 16:01, Maik Musall lists@musall.de wrote:
recently I migrated my mail server from an Ubuntu 16.04 box to an Ubuntu 20.04 box, so from dovecot 2.2.22 to 2.3.7.2, and to openssl 1.1.1.f. While everything else works fine, I have one important user stuck on an iOS 9 device that I need to support for a while longer, with which the IMAP TLS handshake keeps failing. From the logs:
macOS 9 does not support any currently valid and support TLS version and cannot communicate on the Internet securely.
Does anyone have an idea what else I could try?
Have them get an iPad for mail? I don't think they can even use secure webmail.
I think you misread that. It’s not macOS 9, it’s iOS 9. So it IS an iPad, but an iPad mini first generation, which can’t run anything newer than iOS 9.
After a hint via a private email and some more investigation, turns out I would have to lower the overall security level by applying a custom openssl config to dovecot (see https://askubuntu.com/questions/1233186/ubuntu-20-04-how-to-set-lower-ssl-se...). I would be ok to allow ONE cipher/TLS combination that matches what iOS 9 Mail can do, but I’m not willing to do it this way. I’d rather buy the user a newer iPad ;-)
It’s a pity that Apple botched this Mail.app release. They increased security in iOS 9 for all sorts of other things, including requiring TLS 1.2 for app security, but apparently they forgot to update Mail along with it.
Maik
P.S. I got dozens of DMARC warnings on my previous email because my server applied a DKIM signature, and the dovecot mailing list server didn’t remove it and also didn’t apply it’s own… had to exclude mails to this list from being DKIM-signed. So if anyone receives this, but not my previous mail, that is probably the reason.
On 01 Jan 2021, at 16:01, Maik Musall lists@musall.de wrote:
recently I migrated my mail server from an Ubuntu 16.04 box to an Ubuntu 20.04 box, so from dovecot 2.2.22 to 2.3.7.2, and to openssl 1.1.1.f. While everything else works fine, I have one important user stuck on an iOS 9 device that I need to support for a while longer, with which the IMAP TLS handshake keeps failing. From the logs:
macOS 9 does not support any currently valid and support TLS version and cannot communicate on the Internet securely.
Does anyone have an idea what else I could try?
Have them get an iPad for mail? I don't think they can even use secure webmail.
-- All he [Vimes] knew was that you couldn't hope to try for the big stuff, like world peace and happiness, but you might just about be able to achieve some tiny deed that'd make the world, in a small way, a better place. Like shooting someone.
On 01 Jan 2021, at 16:01, Maik Musall lists@musall.de wrote:
recently I migrated my mail server from an Ubuntu 16.04 box to an Ubuntu 20.04 box, so from dovecot 2.2.22 to 2.3.7.2, and to openssl 1.1.1.f. While everything else works fine, I have one important user stuck on an iOS 9 device that I need to support for a while longer, with which the IMAP TLS handshake keeps failing. From the logs:
macOS 9 does not support any currently valid and support TLS version and cannot communicate on the Internet securely.
Does anyone have an idea what else I could try?
Have them get an iPad for mail? I don't think they can even use secure webmail.
-- All he [Vimes] knew was that you couldn't hope to try for the big stuff, like world peace and happiness, but you might just about be able to achieve some tiny deed that'd make the world, in a small way, a better place. Like shooting someone.
On 01 Jan 2021, at 16:01, Maik Musall lists@musall.de wrote:
recently I migrated my mail server from an Ubuntu 16.04 box to an Ubuntu 20.04 box, so from dovecot 2.2.22 to 2.3.7.2, and to openssl 1.1.1.f. While everything else works fine, I have one important user stuck on an iOS 9 device that I need to support for a while longer, with which the IMAP TLS handshake keeps failing. From the logs:
macOS 9 does not support any currently valid and support TLS version and cannot communicate on the Internet securely.
Does anyone have an idea what else I could try?
Have them get an iPad for mail? I don't think they can even use secure webmail.
-- All he [Vimes] knew was that you couldn't hope to try for the big stuff, like world peace and happiness, but you might just about be able to achieve some tiny deed that'd make the world, in a small way, a better place. Like shooting someone.
On 01 Jan 2021, at 17:57, @lbutlr kremels@kreme.com wrote:
Apologies, my Internet connection seems to have died for about an hour and the message sent out several times when it started to come back up.
-- Footnote on the High Energy Magic building: It was here that the thaum, hitherto believed to be the smallest possible particle of magic, was successfully demonstrated to be made up of resons (lit: 'Thing-ies) or reality fragments. Currently research indicates that each reson is itself made up of a combination of at least five 'flavours', known as 'up', 'down', 'sideways', 'sex appeal' and 'peppermint'.
participants (2)
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＠lbutlr
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Maik Musall