NGINX IMAP proxy and outlook ios/android app

[bobykus]

I used tcpdump and ssldump

ssldump -nr /var/tmp/www-ssl-client.cap

New TCP connection #1: 52.166.193.38(14104) <-> 10.32.20.102(993)
1 1  0.0187 (0.0187)  C>S  Handshake
      ClientHello
        Version 3.3 
        resume [32]=
          39 27 b8 51 63 0d 88 f5 47 fa 05 41 d0 b7 ac 3e 
          17 93 05 1b 24 47 a6 77 41 bd 45 07 42 25 de 25 
        cipher suites
        Unknown value 0xc024
        Unknown value 0xc028
        Unknown value 0x3d
        Unknown value 0xc026
        Unknown value 0xc02a
        Unknown value 0x6b
        Unknown value 0x6a
        Unknown value 0xc00a
        Unknown value 0xc014
        TLS_RSA_WITH_AES_256_CBC_SHA
        Unknown value 0xc005
        Unknown value 0xc00f
        TLS_DHE_RSA_WITH_AES_256_CBC_SHA
        TLS_DHE_DSS_WITH_AES_256_CBC_SHA
        Unknown value 0xc023
        Unknown value 0xc027
        Unknown value 0x3c
        Unknown value 0xc025
        Unknown value 0xc029
        TLS_DHE_DSS_WITH_NULL_SHA
        Unknown value 0x40
        Unknown value 0xc009
        Unknown value 0xc013
        TLS_RSA_WITH_AES_128_CBC_SHA
        Unknown value 0xc004
        Unknown value 0xc00e
        TLS_DHE_RSA_WITH_AES_128_CBC_SHA
        TLS_DHE_DSS_WITH_AES_128_CBC_SHA
        Unknown value 0xc02c
        Unknown value 0xc02b
        Unknown value 0xc030
        Unknown value 0x9d
        Unknown value 0xc02e
        Unknown value 0xc032
        Unknown value 0x9f
        Unknown value 0xa3
        Unknown value 0xc02f
        Unknown value 0x9c
        Unknown value 0xc02d
        Unknown value 0xc031
        Unknown value 0x9e
        Unknown value 0xa2
        Unknown value 0xc008
        Unknown value 0xc012
        TLS_RSA_WITH_3DES_EDE_CBC_SHA
        Unknown value 0xc003
        Unknown value 0xc00d
        TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA
        TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA
        Unknown value 0xff
        compression methods
                  NULL
1 2  0.0190 (0.0003)  S>C  Handshake
      ServerHello
        Version 3.3 
        session_id[32]=
          39 27 b8 51 63 0d 88 f5 47 fa 05 41 d0 b7 ac 3e 
          17 93 05 1b 24 47 a6 77 41 bd 45 07 42 25 de 25 
        cipherSuite         Unknown value 0x3d
        compressionMethod                   NULL
1 3  0.0190 (0.0000)  S>C  ChangeCipherSpec
1 4  0.0190 (0.0000)  S>C  Handshake
1 5  0.0370 (0.0180)  C>S  ChangeCipherSpec
1 6  0.0949 (0.0578)  C>S  Handshake
1 7  0.0951 (0.0002)  S>C  application_data
1 8  0.1147 (0.0195)  C>S  application_data
1 9  0.1148 (0.0001)  S>C  application_data
1 10 0.1330 (0.0182)  C>S  application_data
1 11 0.1332 (0.0001)  S>C  application_data
1 12 0.1515 (0.0183)  C>S  Alert
1    0.1516 (0.0000)  C>S  TCP FIN
1    0.1516 (0.0000)  S>C  TCP FIN
New TCP connection #2: 52.166.193.38(14105) <-> 10.32.20.102(993)
2    30.0452 (30.0452)  C>S  TCP FIN
2    30.0453 (0.0000)  S>C  TCP FIN


Not much that can say what is the reason of connection drop

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,276771,276782#msg-276782