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openvpn 警告：未启用服务器证书验证方法

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openvpn 警告：未启用服务器证书验证方法

我尝试在 debian Squeez （服务器）上安装 openvpn 并从我的 fedora 17 作为（客户端）连接。这是我的配置：

服务器配置

# Server TCP
proto tcp
port 1194
dev tun

# Keys and certificates
ca /etc/openvpn/easy-rsa/keys/ca.crt
cert /etc/openvpn/easy-rsa/keys/server.crt
key /etc/openvpn/easy-rsa/keys/server.key
dh /etc/openvpn/easy-rsa/keys/dh1024.pem

# Network
# Virtual address of the VPN network
server 192.170.70.0 255.255.255.0
# This line adds the client to the router network server
push "route 192.168.1.0 255.255.255.0"
# Create a route server to the tun interface
#route 192.170.70.0 255.255.255.0

# Security
keepalive 10 120
# type of data encryption
cipher AES-128-CBC
# enabling compression
comp-lzo
# maximum number of clients allowed
max-clients 10
# no user and group specific to the use of the VPN
user nobody
group nogroup

# to make persistent connection
persist-key
persist-tun

# Log of the OpenVPN status
status /var/log/openvpn-status.log

# logs openvpnlog /var/log/openvpn.log
log-append /var/log/openvpn.log

# verbosity
verb 5

客户端配置

client
dev tun
proto tcp-client
remote <my server wan IP> 1194
resolv-retry infinite
cipher AES-128-CBC

# Keys
ca ca.crt
cert client.crt
key client.key

# Security
nobind
persist-key
persist-tun
comp-lzo
verb 3

日志文件中来自主机客户端 (fedora 17) 的消息/var/log/messages：

Dec  6 21:56:00 GlobalTIC NetworkManager[691]: <info> Starting VPN service 'openvpn'...
Dec  6 21:56:00 GlobalTIC NetworkManager[691]: <info> VPN service 'openvpn' started (org.freedesktop.NetworkManager.openvpn), PID 7470
Dec  6 21:56:00 GlobalTIC NetworkManager[691]: <info> VPN service 'openvpn' appeared; activating connections
Dec  6 21:56:00 GlobalTIC NetworkManager[691]: <info> VPN plugin state changed: starting (3)
Dec  6 21:56:01 GlobalTIC NetworkManager[691]: <info> VPN connection 'Connexion VPN 1' (Connect) reply received.
Dec  6 21:56:01 GlobalTIC nm-openvpn[7472]: OpenVPN 2.2.2 x86_64-redhat-linux-gnu [SSL] [LZO2] [EPOLL] [PKCS11] [eurephia] built on Sep  5 2012
Dec  6 21:56:01 GlobalTIC nm-openvpn[7472]:[COLOR="Red"][U][B] WARNING: No server certificate verification method has been enabled.[/B][/U][/COLOR]  See http://openvpn.net/howto.html#mitm for more info.
Dec  6 21:56:01 GlobalTIC nm-openvpn[7472]: NOTE: the current --script-security setting may allow this configuration to call user-defined scripts
Dec  6 21:56:01 GlobalTIC nm-openvpn[7472]:[COLOR="Red"] WARNING: file '/home/login/client/client.key' is group or others accessible[/COLOR]
Dec  6 21:56:01 GlobalTIC nm-openvpn[7472]: UDPv4 link local: [undef]
Dec  6 21:56:01 GlobalTIC nm-openvpn[7472]: UDPv4 link remote: [COLOR="Red"]<my server wan IP>[/COLOR]:1194
Dec  6 21:56:01 GlobalTIC nm-openvpn[7472]: [COLOR="Red"]read UDPv4 [ECONNREFUSED]: Connection refused (code=111)[/COLOR]
Dec  6 21:56:03 GlobalTIC nm-openvpn[7472]: [COLOR="Red"]read UDPv4[/COLOR] [ECONNREFUSED]: Connection refused (code=111)
Dec  6 21:56:07 GlobalTIC nm-openvpn[7472]: read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Dec  6 21:56:15 GlobalTIC nm-openvpn[7472]: read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Dec  6 21:56:31 GlobalTIC nm-openvpn[7472]: read UDPv4 [ECONNREFUSED]: Connection refused (code=111)
Dec  6 21:56:41 GlobalTIC NetworkManager[691]: <warn> VPN connection 'Connexion VPN 1' (IP Conf[/CODE]

服务器主机上的 ifconfig (debian):

ifconfig 
eth0      Link encap:Ethernet  HWaddr 08:00:27:16:21:ac  
          inet addr:192.168.1.6  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::a00:27ff:fe16:21ac/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:9059 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5660 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:919427 (897.8 KiB)  TX bytes:1273891 (1.2 MiB)
tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
          inet addr:192.170.70.1  P-t-P:192.170.70.2  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

客户端主机上的 ifconfig (fedora 17)

as0t0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1500
        inet 5.5.0.1  netmask 255.255.252.0  destination 5.5.0.1
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 200  (UNSPEC)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2  bytes 321 (321.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

as0t1: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1500
        inet 5.5.4.1  netmask 255.255.252.0  destination 5.5.4.1
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 200  (UNSPEC)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2  bytes 321 (321.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

as0t2: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1500
        inet 5.5.8.1  netmask 255.255.252.0  destination 5.5.8.1
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 200  (UNSPEC)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2  bytes 321 (321.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

as0t3: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1500
        inet 5.5.12.1  netmask 255.255.252.0  destination 5.5.12.1
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 200  (UNSPEC)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2  bytes 321 (321.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

**p255p1**: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.2  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::21d:baff:fe20:b7e6  prefixlen 64  scopeid 0x20<link>
        ether 00:1d:ba:20:b7:e6  txqueuelen 1000  (Ethernet)
        RX packets 4842070  bytes 3579798184 (3.3 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 3996158  bytes 2436442882 (2.2 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 16

p255p1 是 eth0 接口的标签

和

在服务器上：

root@hoteserver:/etc/openvpn# tree
.
├── client
│** ├── ca.crt
│** ├── client.conf
│** ├── client.crt
│** ├── client.csr
│** ├── client.key
│** ├── client.ovpn
│*
│** 
├── easy-rsa
│** ├── build-ca
│** ├── build-dh
│** ├── build-inter
│** ├── build-key
│** ├── build-key-pass
│** ├── build-key-pkcs12
│** ├── build-key-server
│** ├── build-req
│** ├── build-req-pass
│** ├── clean-all
│** ├── inherit-inter
│** ├── keys
│** │** ├── 01.pem
│** │** ├── 02.pem
│** │** ├── ca.crt
│** │** ├── ca.key
│** │** ├── client.crt
│** │** ├── client.csr
│** │** ├── client.key
│** │** ├── dh1024.pem
│** │** ├── index.txt
│** │** ├── index.txt.attr
│** │** ├── index.txt.attr.old
│** │** ├── index.txt.old
│** │** ├── serial
│** │** ├── serial.old
│** │** ├── server.crt
│** │** ├── server.csr
│** │** └── server.key
│** ├── list-crl
│** ├── Makefile
│** ├── openssl-0.9.6.cnf.gz
│** ├── openssl.cnf
│** ├── pkitool
│** ├── README.gz
│** ├── revoke-full
│** ├── sign-req
│** ├── vars
│** └── whichopensslcnf
├── openvpn.log
├── openvpn-status.log
├── server.conf
└── update-resolv-conf

在客户端：

[login@hoteclient openvpn]$ tree 
.
|-- easy-rsa
|   |-- 1.0
|   |   |-- build-ca
|   |   |-- build-dh
|   |   |-- build-inter
|   |   |-- build-key
|   |   |-- build-key-pass
|   |   |-- build-key-pkcs12
|   |   |-- build-key-server
|   |   |-- build-req
|   |   |-- build-req-pass
|   |   |-- clean-all
|   |   |-- list-crl
|   |   |-- make-crl
|   |   |-- openssl.cnf
|   |   |-- README
|   |   |-- revoke-crt
|   |   |-- revoke-full
|   |   |-- sign-req
|   |   `-- vars
|   `-- 2.0
|       |-- build-ca
|       |-- build-dh
|       |-- build-inter
|       |-- build-key
|       |-- build-key-pass
|       |-- build-key-pkcs12
|       |-- build-key-server
|       |-- build-req
|       |-- build-req-pass
|       |-- clean-all
|       |-- inherit-inter
|       |-- keys [error opening dir]
|       |-- list-crl
|       |-- Makefile
|       |-- openssl-0.9.6.cnf
|       |-- openssl-0.9.8.cnf
|       |-- openssl-1.0.0.cnf
|       |-- pkitool
|       |-- README
|       |-- revoke-full
|       |-- sign-req
|       |-- vars
|       `-- whichopensslcnf
|-- keys -> ./easy-rsa/2.0/keys/
`-- server.conf

问题的根源是cipher AES-128-CBCUDPproto tcp-client还是Fedora17上的接口或者没有找到p255p1文件验证？ta.key

答案1

首先，您应该更改文件的权限/home/login/client/client.key，以便组或其他人无法访问该文件。

chmod 400 /home/login/client/client.key

然后按照描述这里您应该实现一种方法来检查您的客户端是否连接到正确的服务器并且不可能发生中间人攻击。

答案2

这里有完整的问题列表，您应该认真对待 OpenVPN 给出的警告。但只有警告，而不是导致连接问题的原因。 NetworkManager 的 openvpn 插件正在尝试使用 UDP 进行连接。我不知道您的 client.conf 与您的实际客户端配置有什么关系。是否用于将 VPN 设置导入 NetworkManager？
无论如何，您必须在 VPN 连接配置文件的高级设置对话框中选中 TCP 连接复选框。
由于您似乎没有在客户端或服务器端使用 tls-auth，因此不应丢失 ta.key 文件（但使用 tls-auth 是一个好主意）。
双方的密码似乎是相同的，应该不成问题。
我真的强烈建议到验证服务器证书正如莫利克斯所说。

答案3

要消除No server certificate verification method has been enabled警告，请生成具有正确extendedKeyUsage扩展名的客户端和服务器证书，并将其添加remote-cert-tls server到客户端的openvpn.conf.

将两个部分添加到您的 CA 中openssl.cnf：

[server_cert]
basicConstraints = CA:FALSE
nsCertType = server
nsComment = "OpenSSL Generated Server Certificate"
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer:always
keyUsage = critical, digitalSignature, keyEncipherment
extendedKeyUsage = serverAuth

[client_cert]
basicConstraints = CA:FALSE
nsCertType = client, email
nsComment = "OpenSSL Generated Client Certificate"
subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid,issuer
keyUsage = critical, nonRepudiation, digitalSignature, keyEncipherment
extendedKeyUsage = clientAuth, emailProtection

在您的 CA 处签署服务器证书，如下所示：

openssl ca -config openssl.cnf -extensions server_cert -notext -md sha256 -in csr.pem -out cert.pem

像这样签署客户端证书：

openssl ca -config openssl.cnf -extensions client_cert -notext -md sha256 -in csr.pem -out cert.pem

然后在您的客户端中openvpn.cnf添加以下行：

remote-cert-tls server

并重新启动 openvpn 服务。

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