我想通过 OpneVPN 连接隧道传输所有本地网络流量。我在互联网上配置了一个 ubuntu 服务器（它在我的笔记本电脑上运行），现在正在尝试配置 Raspberry 以接收 eth0 上的所有流量并通过 eth1 隧道传输。
但是，我无法让它工作。我预计现在 ifconfig 中会有一个“tun0”之类的东西，但没有：
pi@raspberrypi ~ $ ifconfig
eth0 Link encap:Ethernet HWaddr b8:27:eb:63:05:18
inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1974 errors:0 dropped:0 overruns:0 frame:0
TX packets:159 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:130750 (127.6 KiB) TX bytes:9302 (9.0 KiB)
eth1 Link encap:Ethernet HWaddr 00:0e:c6:fa:85:06
inet addr:192.168.0.252 Bcast:192.168.15.255 Mask:255.255.240.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:46828 errors:0 dropped:1006 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:4085487 (3.8 MiB) TX bytes:761137 (743.2 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:150 errors:0 dropped:0 overruns:0 frame:0
TX packets:150 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:10495 (10.2 KiB) TX bytes:10495 (10.2 KiB)
我确实向 iptables 添加了以下规则（并采用了教程）
sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE -m comment --comment "Use VPN IP for eth0"
sudo iptables -t nat -A POSTROUTING -o tun0 -j MASQUERADE -m comment --comment "Use VPN IP for tun0"
sudo iptables -A FORWARD -s192.168.0.0/24 -i eth1 -o eth0 -m conntrack --ctstate NEW -j REJECT -m comment --comment "Block traffic from clients to eth0"
sudo iptables -A FORWARD -s192.168.0.0/24 -i eth1 -o tun0 -m conntrack --ctstate NEW -j ACCEPT -m comment --comment "Allow only traffic from clients to tun0"
但由于 tun0 不存在，我猜什么都不会重定向。此外，虽然互联网连接在 RPi 上有效，但它不会通过隧道，而是直接连接到互联网。
最后，这是我的 openVPN 配置文件（最后删除了证书）：
##############################################
# Sample client-side OpenVPN 2.0 config file #
# for connecting to multi-client server. #
# #
# This configuration can be used by multiple #
# clients, however each client should have #
# its own cert and key files. #
# #
# On Windows, you might want to rename this #
# file so it has a .ovpn extension #
##############################################
# Specify that we are a client and that we
# will be pulling certain config file directives
# from the server.
client
# Use the same setting as you are using on
# the server.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
;dev tap
dev tun
#ifconfig 10.8.0.2 10.8.0.1
# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel
# if you have more than one. On XP SP2,
# you may need to disable the firewall
# for the TAP adapter.
;dev-node MyTap
# Are we connecting to a TCP or
# UDP server? Use the same setting as
# on the server.
;proto tcp
proto udp
# The hostname/IP and port of the server.
# You can have multiple remote entries
# to load balance between the servers.
remote xxx.xxx.xxx.xxx 1194
;remote my-server-2 1194
# Choose a random host from the remote
# list for load-balancing. Otherwise
# try hosts in the order specified.
;remote-random
# Keep trying indefinitely to resolve the
# host name of the OpenVPN server. Very useful
# on machines which are not permanently connected
# to the internet such as laptops.
resolv-retry infinite
# Most clients don't need to bind to
# a specific local port number.
nobind
# Downgrade privileges after initialization (non-Windows only)
user nobody
group nogroup
# Try to preserve some state across restarts.
persist-key
persist-tun
# If you are connecting through an
# HTTP proxy to reach the actual OpenVPN
# server, put the proxy server/IP and
# port number here. See the man page
# if your proxy server requires
# authentication.
;http-proxy-retry # retry on connection failures
;http-proxy [proxy server] [proxy port #]
# Wireless networks often produce a lot
# of duplicate packets. Set this flag
# to silence duplicate packet warnings.
;mute-replay-warnings
# SSL/TLS parms.
# See the server config file for more
# description. It's best to use
# a separate .crt/.key file pair
# for each client. A single ca
# file can be used for all clients.
#ca ca.crt
#cert client.crt
#key client.key
# Verify server certificate by checking
# that the certicate has the nsCertType
# field set to "server". This is an
# important precaution to protect against
# a potential attack discussed here:
# http://openvpn.net/howto.html#mitm
#
# To use this feature, you will need to generate
# your server certificates with the nsCertType
# field set to "server". The build-key-server
# script in the easy-rsa folder will do this.
ns-cert-type server
# If a tls-auth key is used on the server
# then every client must also have the key.
;tls-auth ta.key 1
# Select a cryptographic cipher.
# If the cipher option is used on the server
# then you must also specify it here.
;cipher x
# Enable compression on the VPN link.
# Don't enable this unless it is also
# enabled in the server config file.
comp-lzo
# Set log file verbosity.
verb 3
# Silence repeating messages
;mute 20
这些是 syslog 中的日志项：
Apr 12 16:06:26 raspberrypi ovpn-server[3279]: OpenVPN 2.2.1 arm-linux-gnueabihf [SSL] [LZO2] [EPOLL] [PKCS11] [eurephia] [MH] [PF_INET6] [IPv6 payload 20110424-2 (2.2RC2)] built on Dec 1 2014
Apr 12 16:06:26 raspberrypi ovpn-server[3279]: NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables
Apr 12 16:06:26 raspberrypi ovpn-server[3279]: LZO compression initialized
Apr 12 16:06:26 raspberrypi ovpn-server[3279]: Control Channel MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ]
Apr 12 16:06:26 raspberrypi ovpn-server[3279]: Socket Buffers: R=[163840->131072] S=[163840->131072]
Apr 12 16:06:26 raspberrypi ovpn-server[3279]: Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ]
Apr 12 16:06:26 raspberrypi ovpn-server[3279]: Local Options hash (VER=V4): '41690919'
Apr 12 16:06:26 raspberrypi ovpn-server[3279]: Expected Remote Options hash (VER=V4): '530fdded'
Apr 12 16:06:26 raspberrypi ovpn-server[3280]: NOTE: UID/GID downgrade will be delayed because of --client, --pull, or --up-delay
Apr 12 16:06:26 raspberrypi ovpn-server[3280]: UDPv4 link local: [undef]
Apr 12 16:06:26 raspberrypi ovpn-server[3280]: UDPv4 link remote: [AF_INET]185.27.174.62:1194
Apr 12 16:06:26 raspberrypi ovpn-server[3280]: TLS: Initial packet from [AF_INET]185.27.174.62:1194, sid=9bf9a964 2f78ece0
Apr 12 16:06:26 raspberrypi ovpn-server[3280]: VERIFY OK: depth=1, /C=IE/ST=KE/L=xxx/O=xxx/OU=IT/CN=VPN_tunnel_cert/name=server/emailAddress=xxx
Apr 12 16:06:26 raspberrypi ovpn-server[3280]: VERIFY OK: nsCertType=SERVER
Apr 12 16:06:26 raspberrypi ovpn-server[3280]: VERIFY OK: depth=0, /C=IE/ST=KE/L=xxx/O=xxx/OU=IT/CN=server/name=server/emailAddress=xxx
Apr 12 16:07:26 raspberrypi ovpn-server[3280]: TLS Error: TLS key negotiation failed to occur within 60 seconds (check your network connectivity)
Apr 12 16:07:26 raspberrypi ovpn-server[3280]: TLS Error: TLS handshake failed
Apr 12 16:07:26 raspberrypi ovpn-server[3280]: TCP/UDP: Closing socket
Apr 12 16:07:26 raspberrypi ovpn-server[3280]: SIGUSR1[soft,tls-error] received, process restarting
Apr 12 16:07:26 raspberrypi ovpn-server[3280]: Restart pause, 2 second(s)
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: Re-using SSL/TLS context
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: LZO compression initialized
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: Control Channel MTU parms [ L:1542 D:138 EF:38 EB:0 ET:0 EL:0 ]
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: Socket Buffers: R=[163840->131072] S=[163840->131072]
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: Data Channel MTU parms [ L:1542 D:1450 EF:42 EB:135 ET:0 EL:0 AF:3/1 ]
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: Local Options hash (VER=V4): '41690919'
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: Expected Remote Options hash (VER=V4): '530fdded'
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: UDPv4 link local: [undef]
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: UDPv4 link remote: [AF_INET]xxx.xxx.xxx.xxx:1194
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: TLS: Initial packet from [AF_INET]185.27.174.62:1194, sid=d2b65489 e5492d4d
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: VERIFY OK: depth=1, /C=IE/ST=KE/L=xxx/O=xxx/OU=IT/CN=VPN_tunnel_cert/name=server/emailAddress=xxx
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: VERIFY OK: nsCertType=SERVER
Apr 12 16:07:28 raspberrypi ovpn-server[3280]: VERIFY OK: depth=0, /C=IE/ST=KE/L=xxx/O=xxx/OU=IT/CN=server/name=server/emailAddress=xxx