背景如下：
朋友的 FreeSWITCH 部署在公网
MicroSIP transport=tls 能成功注册到 FreeSWITCH
但 Linphone linphone-android-6.0.17.apk tls 不行，注册失败（当然不是密码不正确，不是这类容易问题）
于是我找了一个公网服务器，安装 Kamailio 和 ssldump 进行跟踪
主要过程如下：
kamailio listen
tls: 192.168.99.203 [192.168.99.203]:12291 advertise tls:11.22.33.44:12291 # 公网地址是假的
tls.cfg 内容为：
[server:default]
method = TLSv1.2
verify_certificate = no
require_certificate = no
private_key = /etc/kamailio/privkey.pem
certificate = /etc/kamailio/cert.pem
cipher_list = AES128-SHA256
[client:default]
verify_certificate = no
require_certificate = no
自签名证书
专门配置了加密套件
运行 ssldump -i any port 12291 -d -k privkey.pem
启动 MicroSIP, 配置 sip 传输为 tls
ssldump 详细信息为：
New TCP connection #1: 113.84.64.28(24944) <-> 192.168.99.203(12291)
1 11.5501 (11.5501) C>S TCP FIN
1 11.5520 (0.0019) S>C TCP FIN
New TCP connection #2: 113.84.64.28(24949) <-> 192.168.99.203(12291)
2 1 0.0403 (0.0403) C>S Handshake
ClientHello
Version 3.3
cipher suites
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256
TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
TLS_DHE_RSA_WITH_AES_256_CBC_SHA256
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
TLS_DHE_RSA_WITH_AES_128_CBC_SHA256
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
TLS_DHE_RSA_WITH_AES_256_CBC_SHA
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA
TLS_DHE_RSA_WITH_AES_128_CBC_SHA
TLS_RSA_WITH_AES_256_GCM_SHA384
TLS_RSA_WITH_AES_128_GCM_SHA256
TLS_RSA_WITH_AES_256_CBC_SHA256
TLS_RSA_WITH_AES_128_CBC_SHA256
TLS_RSA_WITH_AES_256_CBC_SHA
TLS_RSA_WITH_AES_128_CBC_SHA
TLS_EMPTY_RENEGOTIATION_INFO_SCSV
compression methods
NULL
extensions
ec_point_formats
ec point format uncompressed
ec point format ansiX962_compressed_prime
ec point format ansiX962_compressed_char2
supported_groups
supported group x25519
supported group