iPhone用户不连接到StrongSwan虚拟专用网，而安卓和Windows 10用户连接吗？

Question

我有一个StrongSwan虚拟专用网，由于某种原因我无法将iOS用户连接到我的VPN服务器。

几个快速笔记：

• 我的StrongSwan服务器是连接到我的网络的VPN客户端的前端。我使用WireGuard作为后端站点到站点的路由。
• 所有StrongSwan虚拟专用网用户都在FreeRadius服务器上进行验证。
• StrongSwan客户端在192.168.201.0/24子网上分配IP，而WireGuard骨干网在192.168.200.0/24子网上运行。
• 所有客户端都会收到一个属于分配给我的IPv6子网的公共/48地址。

我在Ubuntu20.04上运行StrongSwan，我的配置文件位于/etc/swanctl/config/文件夹中，默认情况下包括在.conf上的文件名结束。

内容如下：

# Default VPN server settings for all connections
conn-defaults {
    local_addrs = PUBLIC_IPV4, PUBLIC_IPV6

    local {
      auth = pubkey
      certs = vpn-ecdsa.cer
      id = vpn.example.com
    }

    version = 2
    send_certreq = no
    send_cert = always
    unique = never
    fragmentation = yes
    encap = yes
    dpd_delay = 60s

    rekey_time = 0s
}

# Default login method
eap-defaults {
  remote {
   auth = eap-radius
   id = %any
   eap_id = %any
  }
}

connections
{
  # Generic Android configuration that is extended further down.
  #
  # Works with StrongSwan VPN client for Android
  conn-unix : conn-defaults, eap-defaults {
    children {
      net {
        local_ts = 0.0.0.0/0, ::/0
      }

      net-unix : child-defaults {
      }

      esp_proposals = aes128gcm128-x25519
    }

    proposals = aes128-sha256-x25519
  }

  # All Windows klients matches this rule as username validation 
  # is done by 'eap_start = yes' in strongswan.conf. 
  #
  # Works with Windows 10 built-in VPN client.
  conn-windows : conn-defaults, eap-defaults {
    children {
      net {
        local_ts = 0.0.0.0/0, ::/0
      }

      esp_proposals = aes256-sha256-prfsha256-modp1024
    }

    proposals = aes256-sha256-prfsha256-modp1024
    pools = IkeVPN-site-ipv4, IkeVPN-site-ipv6

  }

  # A very similar configuration to Windows clients 
  # configuration, except iOS uses 2048 bit keys, 
  # while Windows uses 1024 bit keys.
  #
  # Does NOT work in its current state.
  conn-ios : conn-defaults, eap-defaults {
    children {
      net {
        local_ts = 0.0.0.0/0, ::/0
      }

      esp_proposals = aes256-sha2_256
      pools = IkeVPN-site-ipv4, IkeVPN-site-ipv6

    }

    proposals = aes256-sha256-prfsha256-modp2048
  }

  # Android users is matched against this connection as they are 
  # running the app StrongSwan VPN client. Username is passed in the
  # 'id' field to StrongSwan VPN server.
  conn-unix-site : connections.conn-unix {
    remote {
      id = *@site.example.com
    }
    pools = IkeVPN-site-ipv4, IkeVPN-site-ipv6
  }
}

pools
{
   IkeVPN-site-ipv4 {
      addrs = 192.168.201.0/24
      dns = 192.168.200.1
   }

   IkeVPN-site-ipv6 {
      addrs = 2001:db8:cafe::/97
      dns = 2001:db8::1
   }
}

我的配置是使用以下网页提供的结构创建的：

https://wiki.strongswan.org/projects/strongswan/wiki/Strongswanconf#Referencing-other-Sections

我之所以使用它，是因为避免在所有连接配置文件中重复相同的配置设置。

如果您不熟悉这个设置，那么conn-ios的以下配置应该被认为是等效的：

conn-ios {
   # Obtained from conn-default
   local_addrs = PUBLIC_IPV4, PUBLIC_IPV6

   local {
      auth = pubkey
      certs = vpn-ecdsa.cer
      id = vpn.example.com
   }

   version = 2
   send_certreq = no
   send_cert = always
   unique = never
   fragmentation = yes
   encap = yes
   dpd_delay = 60s

   rekey_time = 0s

   # Obtained from eap-defaults
   remote {
      auth = eap-radius
      id = %any
      eap_id = %any
   }

   # Obtained from original conn-ios profile above.
   children {
      net {
         local_ts = 0.0.0.0/0, ::/0
      }

      esp_proposals = aes256-sha2_256
      pools = IkeVPN-site-ipv4, IkeVPN-site-ipv6
   }

   proposals = aes256-sha256-prfsha256-modp2048
}

conn-default部分中列出的服务器证书是从使用Acme.sh加密获得的ECDSA证书。

proposals和esp_proposals在iOS配置中的加密值来自于https://wiki.strongswan.org/projects/strongswan/wiki/AppleClients中的提示。

当测试Android或Windows的所有组合时，用户连接没有任何问题，但是当有人试图使用iPhone登录时，连接就会中断。

当iPhone试图连接时，日志的输出如下：

10[IKE] CLIENT_IPV4 is initiating an IKE_SA
10[CFG] received proposals: IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_2048, IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_256, IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1536, IKE:AES_CBC_128/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024, IKE:3DES_CBC/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024
10[CFG] configured proposals: IKE:AES_CBC_128/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/CURVE_25519
10[IKE] no matching proposal found, trying alternative config
10[CFG] received proposals: IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_2048, IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_256, IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1536, IKE:AES_CBC_128/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024, IKE:3DES_CBC/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024
10[CFG] configured proposals: IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1024
10[IKE] no matching proposal found, trying alternative config
10[CFG] selected proposal: IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_2048
10[IKE] remote host is behind NAT
10[ENC] generating IKE_SA_INIT response 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) N(FRAG_SUP) N(CHDLESS_SUP) N(MULT_AUTH) ]
10[NET] sending packet: from PUBLIC_IPV4[500] to CLIENT_IPV4[6452] (456 bytes)
06[NET] received packet: from CLIENT_IPV4[13549] to PUBLIC_IPV4[4500] (512 bytes)
06[ENC] unknown attribute type INTERNAL_DNS_DOMAIN
06[ENC] parsed IKE_AUTH request 1 [ IDi N(INIT_CONTACT) IDr CPRQ(ADDR MASK DHCP DNS ADDR6 DHCP6 DNS6 DOMAIN) N(ESP_TFC_PAD_N) N(NON_FIRST_FRAG) SA TSi TSr N(MOBIKE_SUP) ]
06[CFG] looking for peer configs matching PUBLIC_IPV4[vpn.example.com]...CLIENT_IPV4[PRIVATE_CLASS_A_ADDRESS]
06[CFG] selected peer config 'conn-ios'
06[IKE] initiating EAP_IDENTITY method (id 0x00)
06[IKE] received ESP_TFC_PADDING_NOT_SUPPORTED, not using ESPv3 TFC padding
06[IKE] peer supports MOBIKE
06[IKE] authentication of 'vpn.example.com' (myself) with ECDSA-256 signature successful
06[IKE] sending end entity cert "CN=vpn.example.com"
06[IKE] sending issuer cert "C=US, O=Let's Encrypt, CN=R3"
06[ENC] generating IKE_AUTH response 1 [ IDr CERT CERT AUTH EAP/REQ/ID ]
06[ENC] splitting IKE message (2816 bytes) into 3 fragments
06[ENC] generating IKE_AUTH response 1 [ EF(1/3) ]
06[ENC] generating IKE_AUTH response 1 [ EF(2/3) ]
06[ENC] generating IKE_AUTH response 1 [ EF(3/3) ]
06[NET] sending packet: from PUBLIC_IPV4[4500] to CLIENT_IPV4[13549] (1236 bytes)
06[NET] sending packet: from PUBLIC_IPV4[4500] to CLIENT_IPV4[13549] (1236 bytes)
06[NET] sending packet: from PUBLIC_IPV4[4500] to CLIENT_IPV4[13549] (500 bytes)
11[JOB] deleting half open IKE_SA with CLIENT_IPV4 after timeout

iPhone用户使用以下设置使用内置VPN客户端进行连接：

• IKEv2型
• 描述: VPN服务器
• 服务器: vpn.example.com
• 远程id: vpn.example.com
• 本地id:空白
• 用户名和密码认证。
• 用户名: user@site.example.com
• 密码: ItIsASecret

有人知道为什么当iOS用户加载了conn-ios配置文件后，连接就会停止吗？

更新，我们已经起飞！:-)

根据@ecdsa的建议，我已经将证书转换为2048位RSA证书。

我的Radius服务器被呼叫了。用户身份验证成功，客户端获得分配ip-adresse。我很高兴。:-)

我现在对conn-ios的配置是：

  conn-ios : conn-defaults, eap-defaults {

    # Overriding defaults from 'conn-default'
    local {
      auth = pubkey
      certs = vpn-rsa.cer
      id = vpn.example.com
    }

    children {
      net {
        local_ts = 0.0.0.0/0, ::/0
      }

      esp_proposals = aes256-sha256
    }

    pools = IkeVPN-site-ipv4, IkeVPN-site-ipv6
    proposals = aes256-sha256-prfsha256-modp2048
  }

其他一切都是从我最初的配置开始的。

Answer 1

正如我们在日志中看到的，客户机不支持RFC 7427 (否则，哈希算法通知将在IKE_SA_INIT期间进行交换)，后者定义了灵活的基于签名的身份验证。

虽然IKEv2也支持没有扩展的ECDSA，但RFC 4754只增加了对它的有限支持(只能使用三条NIST曲线，并且每个曲线都有一个特定的哈希算法)。因此，苹果客户端可能只接受/使用在配置剖面中显式配置的ECDSA (有一个选项CertificateType可以设置为ECDSA256)。

如果使用配置配置文件不是一种选择，那么唯一的选择就是使用RSA服务器证书，至少直到苹果在其IKEv2客户端中实现对RFC 7427的支持为止。