我正在尝试使用本指南在服务器上设置 openvpn： https://www.digitalocean.com/community/tutorials/how-to-set-up-and-configure-an-openvpn-server-on-ubuntu-22-04
我进行到第 10 步，但无法启动 openvpn 服务：
serv_ivan@964889-cd87180:~$ sudo systemctl -f enable [email protected]
[sudo] password for serv_ivan:
serv_ivan@964889-cd87180:~$ sudo systemctl start [email protected]
serv_ivan@964889-cd87180:~$ sudo systemctl status [email protected]
● [email protected] - OpenVPN service for server
Loaded: loaded (/lib/systemd/system/[email protected]; enabled; vendor preset: enabled)
Active: activating (auto-restart) (Result: exit-code) since Mon 2022-08-01 21:33:03 MSK; 3s ago
Docs: man:openvpn(8)
https://community.openvpn.net/openvpn/wiki/Openvpn24ManPage
https://community.openvpn.net/openvpn/wiki/HOWTO
Process: 1256469 ExecStart=/usr/sbin/openvpn --status /run/openvpn-server/status-server.log --status-version 2 --suppress-timestamps --config server.conf (code=exited, status=1/FAILURE)
Main PID: 1256469 (code=exited, status=1/FAILURE)
Status: "Pre-connection initialization successful"
CPU: 24ms
Aug 01 21:33:03 964889-cd87180.tmweb.ru systemd[1]: [email protected]: Main process exited, code=exited, status=1/FAILURE
Aug 01 21:33:03 964889-cd87180.tmweb.ru systemd[1]: [email protected]: Failed with result 'exit-code'.
serv_ivan@964889-cd87180:~$
我在网上搜索答案，但没有找到。
日志：
serv_ivan@964889-cd87180:~$ sudo tail -n 20 /var/log/syslog
Aug 1 21:36:47 964889-cd87180 systemd[1]: Stopped OpenVPN connection to server.
Aug 1 21:36:47 964889-cd87180 systemd[1]: Starting OpenVPN connection to server...
Aug 1 21:36:47 964889-cd87180 ovpn-server[1257478]: Options error: In [CMD-LINE]:1: Error opening configuration file: /etc/openvpn/server.conf
Aug 1 21:36:47 964889-cd87180 ovpn-server[1257478]: Use --help for more information.
Aug 1 21:36:47 964889-cd87180 systemd[1]: [email protected]: Main process exited, code=exited, status=1/FAILURE
Aug 1 21:36:47 964889-cd87180 systemd[1]: [email protected]: Failed with result 'exit-code'.
Aug 1 21:36:47 964889-cd87180 systemd[1]: Failed to start OpenVPN connection to server.
Aug 1 21:36:48 964889-cd87180 systemd[1]: [email protected]: Scheduled restart job, restart counter is at 1733.
Aug 1 21:36:48 964889-cd87180 systemd[1]: Stopped OpenVPN service for server.
Aug 1 21:36:48 964889-cd87180 systemd[1]: Starting OpenVPN service for server...
Aug 1 21:36:48 964889-cd87180 systemd[1]: Started OpenVPN service for server.
Aug 1 21:36:48 964889-cd87180 networkd-dispatcher[1030209]: WARNING:Unknown index 49326 seen, reloading interface list
Aug 1 21:36:48 964889-cd87180 systemd-networkd[1214783]: tun1: Link UP
Aug 1 21:36:48 964889-cd87180 systemd-networkd[1214783]: tun1: Gained carrier
Aug 1 21:36:48 964889-cd87180 systemd-networkd[1214783]: tun1: Gained IPv6LL
Aug 1 21:36:48 964889-cd87180 systemd-udevd[1257483]: Using default interface naming scheme 'v249'.
Aug 1 21:36:48 964889-cd87180 systemd-networkd[1214783]: tun1: Link DOWN
Aug 1 21:36:48 964889-cd87180 systemd-networkd[1214783]: tun1: Lost carrier
Aug 1 21:36:48 964889-cd87180 systemd[1]: [email protected]: Main process exited, code=exited, status=1/FAILURE
Aug 1 21:36:48 964889-cd87180 systemd[1]: [email protected]: Failed with result 'exit-code'.
serv_ivan@964889-cd87180:~$
猫服务器配置：
#################################################
# Sample OpenVPN 2.0 config file for #
# multi-client server. #
# #
# This file is for the server side #
# of a many-clients <-> one-server #
# OpenVPN configuration. #
# #
# OpenVPN also supports #
# single-machine <-> single-machine #
# configurations (See the Examples page #
# on the web site for more info). #
# #
# This config should work on Windows #
# or Linux/BSD systems. Remember on #
# Windows to quote pathnames and use #
# double backslashes, e.g.: #
# "C:\\Program Files\\OpenVPN\\config\\foo.key" #
# #
# Comments are preceded with '#' or ';' #
#################################################
# Which local IP address should OpenVPN
# listen on? (optional)
;local 94.228.120.106
# Which TCP/UDP port should OpenVPN listen on?
# If you want to run multiple OpenVPN instances
# on the same machine, use a different port
# number for each one. You will need to
# open up this port on your firewall.
port 1194
# TCP or UDP server?
;proto tcp
proto udp
# "dev tun" will create a routed IP tunnel,
# "dev tap" will create an ethernet tunnel.
# Use "dev tap0" if you are ethernet bridging
# and have precreated a tap0 virtual interface
# and bridged it with your ethernet interface.
# If you want to control access policies
# over the VPN, you must create firewall
# rules for the the TUN/TAP interface.
# On non-Windows systems, you can give
# an explicit unit number, such as tun0.
# On Windows, use "dev-node" for this.
# 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
# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel if you
# have more than one. On XP SP2 or higher,
# you may need to selectively disable the
# Windows firewall for the TAP adapter.
# Non-Windows systems usually don't need this.
;dev-node MyTap
# SSL/TLS root certificate (ca), certificate
# (cert), and private key (key). Each client
# and the server must have their own cert and
# key file. The server and all clients will
# use the same ca file.
#
# See the "easy-rsa" directory for a series
# of scripts for generating RSA certificates
# and private keys. Remember to use
# a unique Common Name for the server
# and each of the client certificates.
#
# Any X509 key management system can be used.
# OpenVPN can also use a PKCS #12 formatted key file
# (see "pkcs12" directive in man page).
ca ca.crt
cert server.crt
key server.key # This file should be kept secret
# Diffie hellman parameters.
# Generate your own with:
# openssl dhparam -out dh2048.pem 2048
;dh dh2048.pem
dh none
# Network topology
# Should be subnet (addressing via IP)
# unless Windows clients v2.0.9 and lower have to
# be supported (then net30, i.e. a /30 per client)
# Defaults to net30 (not recommended)
;topology subnet
# Configure server mode and supply a VPN subnet
# for OpenVPN to draw client addresses from.
# The server will take 10.8.0.1 for itself,
# the rest will be made available to clients.
# Each client will be able to reach the server
# on 10.8.0.1. Comment this line out if you are
# ethernet bridging. See the man page for more info.
server 10.8.0.0 255.255.255.0
# Maintain a record of client <-> virtual IP address
# associations in this file. If OpenVPN goes down or
# is restarted, reconnecting clients can be assigned
# the same virtual IP address from the pool that was
# previously assigned.
ifconfig-pool-persist /var/log/openvpn/ipp.txt
# Configure server mode for ethernet bridging.
# You must first use your OS's bridging capability
# to bridge the TAP interface with the ethernet
# NIC interface. Then you must manually set the
# IP/netmask on the bridge interface, here we
# assume 10.8.0.4/255.255.255.0. Finally we
# must set aside an IP range in this subnet
# (start=10.8.0.50 end=10.8.0.100) to allocate
# to connecting clients. Leave this line commented
# out unless you are ethernet bridging.
;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100
# Configure server mode for ethernet bridging
# using a DHCP-proxy, where clients talk
# to the OpenVPN server-side DHCP server
# to receive their IP address allocation
# and DNS server addresses. You must first use
# your OS's bridging capability to bridge the TAP
# interface with the ethernet NIC interface.
# Note: this mode only works on clients (such as
# Windows), where the client-side TAP adapter is
# bound to a DHCP client.
;server-bridge
# Push routes to the client to allow it
# to reach other private subnets behind
# the server. Remember that these
# private subnets will also need
# to know to route the OpenVPN client
# address pool (10.8.0.0/255.255.255.0)
# back to the OpenVPN server.
;push "route 192.168.10.0 255.255.255.0"
;push "route 192.168.20.0 255.255.255.0"
# To assign specific IP addresses to specific
# clients or if a connecting client has a private
# subnet behind it that should also have VPN access,
# use the subdirectory "ccd" for client-specific
# configuration files (see man page for more info).
# EXAMPLE: Suppose the client
# having the certificate common name "Thelonious"
# also has a small subnet behind his connecting
# machine, such as 192.168.40.128/255.255.255.248.
# First, uncomment out these lines:
;client-config-dir ccd
;route 192.168.40.128 255.255.255.248
# Then create a file ccd/Thelonious with this line:
# iroute 192.168.40.128 255.255.255.248
# This will allow Thelonious' private subnet to
# access the VPN. This example will only work
# if you are routing, not bridging, i.e. you are
# using "dev tun" and "server" directives.
# EXAMPLE: Suppose you want to give
# Thelonious a fixed VPN IP address of 10.9.0.1.
# First uncomment out these lines:
;client-config-dir ccd
;route 10.9.0.0 255.255.255.252
# Then add this line to ccd/Thelonious:
# ifconfig-push 10.9.0.1 10.9.0.2
# Suppose that you want to enable different
# firewall access policies for different groups
# of clients. There are two methods:
# (1) Run multiple OpenVPN daemons, one for each
# group, and firewall the TUN/TAP interface
# for each group/daemon appropriately.
# (2) (Advanced) Create a script to dynamically
# modify the firewall in response to access
# from different clients. See man
# page for more info on learn-address script.
;learn-address ./script
# If enabled, this directive will configure
# all clients to redirect their default
# network gateway through the VPN, causing
# all IP traffic such as web browsing and
# and DNS lookups to go through the VPN
# (The OpenVPN server machine may need to NAT
# or bridge the TUN/TAP interface to the internet
# in order for this to work properly).
;push "redirect-gateway def1 bypass-dhcp"
# Certain Windows-specific network settings
# can be pushed to clients, such as DNS
# or WINS server addresses. CAVEAT:
# http://openvpn.net/faq.html#dhcpcaveats
# The addresses below refer to the public
# DNS servers provided by opendns.com.
;push "dhcp-option DNS 208.67.222.222"
;push "dhcp-option DNS 208.67.220.220"
# Uncomment this directive to allow different
# clients to be able to "see" each other.
# By default, clients will only see the server.
# To force clients to only see the server, you
# will also need to appropriately firewall the
# server's TUN/TAP interface.
;client-to-client
# Uncomment this directive if multiple clients
# might connect with the same certificate/key
# files or common names. This is recommended
# only for testing purposes. For production use,
# each client should have its own certificate/key
# pair.
#
# IF YOU HAVE NOT GENERATED INDIVIDUAL
# CERTIFICATE/KEY PAIRS FOR EACH CLIENT,
# EACH HAVING ITS OWN UNIQUE "COMMON NAME",
# UNCOMMENT THIS LINE OUT.
;duplicate-cn
# The keepalive directive causes ping-like
# messages to be sent back and forth over
# the link so that each side knows when
# the other side has gone down.
# Ping every 10 seconds, assume that remote
# peer is down if no ping received during
# a 120 second time period.
keepalive 10 120
# For extra security beyond that provided
# by SSL/TLS, create an "HMAC firewall"
# to help block DoS attacks and UDP port flooding.
#
# Generate with:
# openvpn --genkey tls-auth ta.key
#
# The server and each client must have
# a copy of this key.
# The second parameter should be '0'
# on the server and '1' on the clients.
;tls-auth ta.key 0 # This file is secret
tls-crypt ta.key
# Select a cryptographic cipher.
# This config item must be copied to
# the client config file as well.
# Note that v2.4 client/server will automatically
# negotiate AES-256-GCM in TLS mode.
# See also the ncp-cipher option in the manpage
;cipher AES-256-CBC
cipher AES-256-GCM
auth SHA256
# Enable compression on the VPN link and push the
# option to the client (v2.4+ only, for earlier
# versions see below)
;compress lz4-v2
;push "compress lz4-v2"
# For compression compatible with older clients use comp-lzo
# If you enable it here, you must also
# enable it in the client config file.
;comp-lzo
# The maximum number of concurrently connected
# clients we want to allow.
;max-clients 100
# It's a good idea to reduce the OpenVPN
# daemon's privileges after initialization.
#
# You can uncomment this out on
# non-Windows systems.
user nobody
group nobody
# The persist options will try to avoid
# accessing certain resources on restart
# that may no longer be accessible because
# of the privilege downgrade.
persist-key
persist-tun
# Output a short status file showing
# current connections, truncated
# and rewritten every minute.
status /var/log/openvpn/openvpn-status.log
# By default, log messages will go to the syslog (or
# on Windows, if running as a service, they will go to
# the "\Program Files\OpenVPN\log" directory).
# Use log or log-append to override this default.
# "log" will truncate the log file on OpenVPN startup,
# while "log-append" will append to it. Use one
# or the other (but not both).
log /var/log/openvpn/openvpn.log
;log-append /var/log/openvpn/openvpn.log
# Set the appropriate level of log
# file verbosity.
#
# 0 is silent, except for fatal errors
# 4 is reasonable for general usage
# 5 and 6 can help to debug connection problems
# 9 is extremely verbose
verb 3
# Silence repeating messages. At most 20
# sequential messages of the same message
# category will be output to the log.
;mute 20
# Notify the client that when the server restarts so it
# can automatically reconnect.
explicit-exit-notify 1
#mode server
我还注意到 openvpn 无法从该路径打开该文件：
ovpn-server[1257478]: Options error: In [CMD-LINE]:1: Error opening configuration file: /etc/openvpn/server.conf
但事实是我在该路径上没有该文件。这是它的绝对路径：
/etc/openvpn/server/server.conf
但是如果我将文件移动到更高的目录，则会出现以下错误：
serv_ivan@964889-cd87180:/etc/openvpn$ sudo systemctl restart [email protected]
Job for [email protected] failed because the control process exited with error code.
See "systemctl status [email protected]" and "journalctl -xeu [email protected]" for details.
serv_ivan@964889-cd87180:/etc/openvpn$ sudo tail /var/log/syslog
Aug 2 15:17:17 964889-cd87180 systemd[1]: [email protected]: Failed with result 'exit-code'.
Aug 2 15:17:17 964889-cd87180 systemd[1]: Failed to start OpenVPN connection to server.
Aug 2 15:17:18 964889-cd87180 systemd[1]: [email protected]: Scheduled restart job, restart counter is at 13907.
Aug 2 15:17:18 964889-cd87180 systemd[1]: Stopped OpenVPN service for server.
Aug 2 15:17:18 964889-cd87180 systemd[1]: Starting OpenVPN service for server...
Aug 2 15:17:18 964889-cd87180 openvpn[1521409]: Options error: In [CMD-LINE]:1: Error opening configuration file: server.conf
Aug 2 15:17:18 964889-cd87180 openvpn[1521409]: Use --help for more information.
Aug 2 15:17:18 964889-cd87180 systemd[1]: [email protected]: Main process exited, code=exited, status=1/FAILURE
Aug 2 15:17:18 964889-cd87180 systemd[1]: [email protected]: Failed with result 'exit-code'.
Aug 2 15:17:18 964889-cd87180 systemd[1]: Failed to start OpenVPN service for server.
serv_ivan@964889-cd87180:/etc/openvpn$
我尝试更改工作目录的路径，但没有成功：
serv_ivan@964889-cd87180:/etc/openvpn$ cat /usr/lib/systemd/system/[email protected]
[Unit]
Description=OpenVPN service for %I
After=network-online.target
Wants=network-online.target
Documentation=man:openvpn(8)
Documentation=https://community.openvpn.net/openvpn/wiki/Openvpn24ManPage
Documentation=https://community.openvpn.net/openvpn/wiki/HOWTO
[Service]
Type=notify
PrivateTmp=true
#WorkingDirectory=/etc/openvpn/server
WorkingDirectory=/etc/openvpn
ExecStart=/usr/sbin/openvpn --status %t/openvpn-server/status-%i.log --status-version 2 --suppress-timestamps --config %i.conf
CapabilityBoundingSet=CAP_IPC_LOCK CAP_NET_ADMIN CAP_NET_BIND_SERVICE CAP_NET_RAW CAP_SETGID CAP_SETUID CAP_SYS_CHROOT CAP_DAC_OVERRIDE CAP_AUDIT_WRITE
LimitNPROC=10
DeviceAllow=/dev/null rw
DeviceAllow=/dev/net/tun rw
ProtectSystem=true
ProtectHome=true
KillMode=process
RestartSec=5s
Restart=on-failure
[Install]
WantedBy=multi-user.target
serv_ivan@964889-cd87180:/etc/openvpn$
serv_ivan@964889-cd87180:/etc/openvpn$ sudo mv server/server.conf ./
serv_ivan@964889-cd87180:/etc/openvpn$ ls
client server server.conf update-resolv-conf
serv_ivan@964889-cd87180:/etc/openvpn$ sudo systemctl restart [email protected]
Warning: The unit file, source configuration file or drop-ins of [email protected] changed on disk. Run 'systemctl daemon-reload' to reload units.
Job for [email protected] failed because the control process exited with error code.
See "systemctl status [email protected]" and "journalctl -xeu [email protected]" for details.
serv_ivan@964889-cd87180:/etc/openvpn$ sudo systemctl -f enable [email protected]
serv_ivan@964889-cd87180:/etc/openvpn$ sudo systemctl start [email protected]
Job for [email protected] failed because the control process exited with error code.
See "systemctl status [email protected]" and "journalctl -xeu [email protected]" for details.
serv_ivan@964889-cd87180:/etc/openvpn$ sudo systemctl status [email protected]
● [email protected] - OpenVPN service for server
Loaded: loaded (/lib/systemd/system/[email protected]; enabled; vendor preset: enabled)
Active: activating (auto-restart) (Result: exit-code) since Tue 2022-08-02 16:14:59 MSK; 3s ago
Docs: man:openvpn(8)
https://community.openvpn.net/openvpn/wiki/Openvpn24ManPage
https://community.openvpn.net/openvpn/wiki/HOWTO
Process: 1534787 ExecStart=/usr/sbin/openvpn --status /run/openvpn-server/status-server.log --status-version 2 --suppress-timestamps --config server.conf (code=exited, status=1/FAILURE)
Main PID: 1534787 (code=exited, status=1/FAILURE)
CPU: 14ms
Aug 02 16:14:59 964889-cd87180.tmweb.ru systemd[1]: [email protected]: Main process exited, code=exited, status=1/FAILURE
Aug 02 16:14:59 964889-cd87180.tmweb.ru systemd[1]: [email protected]: Failed with result 'exit-code'.
Aug 02 16:14:59 964889-cd87180.tmweb.ru systemd[1]: Failed to start OpenVPN service for server.
serv_ivan@964889-cd87180:/etc/openvpn$
日志：
serv_ivan@964889-cd87180:/etc/openvpn$ sudo systemctl restart [email protected]
Job for [email protected] failed because the control process exited with error code.
See "systemctl status [email protected]" and "journalctl -xeu [email protected]" for details.
serv_ivan@964889-cd87180:/etc/openvpn$ sudo tail -n 30 /var/log/syslog
Aug 2 17:53:54 964889-cd87180 systemd[1]: Failed to start OpenVPN service for server.
Aug 2 17:53:54 964889-cd87180 systemd[1]: [email protected]: Scheduled restart job, restart counter is at 15243.
Aug 2 17:53:54 964889-cd87180 systemd[1]: Stopped OpenVPN connection to server.
Aug 2 17:53:54 964889-cd87180 systemd[1]: Starting OpenVPN connection to server...
Aug 2 17:53:54 964889-cd87180 systemd[1]: [email protected]: Main process exited, code=exited, status=1/FAILURE
Aug 2 17:53:54 964889-cd87180 systemd[1]: [email protected]: Failed with result 'exit-code'.
Aug 2 17:53:54 964889-cd87180 systemd[1]: Failed to start OpenVPN connection to server.
Aug 2 17:53:59 964889-cd87180 systemd[1]: [email protected]: Scheduled restart job, restart counter is at 15708.
Aug 2 17:53:59 964889-cd87180 systemd[1]: Stopped OpenVPN service for server.
Aug 2 17:53:59 964889-cd87180 systemd[1]: Starting OpenVPN service for server...
Aug 2 17:53:59 964889-cd87180 systemd[1]: [email protected]: Main process exited, code=exited, status=1/FAILURE
Aug 2 17:53:59 964889-cd87180 systemd[1]: [email protected]: Failed with result 'exit-code'.
Aug 2 17:53:59 964889-cd87180 systemd[1]: Failed to start OpenVPN service for server.
Aug 2 17:54:00 964889-cd87180 systemd[1]: [email protected]: Scheduled restart job, restart counter is at 15244.
Aug 2 17:54:00 964889-cd87180 systemd[1]: Stopped OpenVPN connection to server.
Aug 2 17:54:00 964889-cd87180 systemd[1]: Starting OpenVPN connection to server...
Aug 2 17:54:00 964889-cd87180 systemd[1]: [email protected]: Main process exited, code=exited, status=1/FAILURE
Aug 2 17:54:00 964889-cd87180 systemd[1]: [email protected]: Failed with result 'exit-code'.
Aug 2 17:54:00 964889-cd87180 systemd[1]: Failed to start OpenVPN connection to server.
Aug 2 17:54:01 964889-cd87180 systemd[1]: Stopped OpenVPN service for server.
Aug 2 17:54:01 964889-cd87180 systemd[1]: Starting OpenVPN service for server...
Aug 2 17:54:01 964889-cd87180 systemd[1]: [email protected]: Main process exited, code=exited, status=1/FAILURE
Aug 2 17:54:01 964889-cd87180 systemd[1]: [email protected]: Failed with result 'exit-code'.
Aug 2 17:54:01 964889-cd87180 systemd[1]: Failed to start OpenVPN service for server.
Aug 2 17:54:05 964889-cd87180 systemd[1]: [email protected]: Scheduled restart job, restart counter is at 15245.
Aug 2 17:54:05 964889-cd87180 systemd[1]: Stopped OpenVPN connection to server.
Aug 2 17:54:05 964889-cd87180 systemd[1]: Starting OpenVPN connection to server...
Aug 2 17:54:05 964889-cd87180 systemd[1]: [email protected]: Main process exited, code=exited, status=1/FAILURE
Aug 2 17:54:05 964889-cd87180 systemd[1]: [email protected]: Failed with result 'exit-code'.
Aug 2 17:54:05 964889-cd87180 systemd[1]: Failed to start OpenVPN connection to server.
serv_ivan@964889-cd87180:/etc/openvpn$
答案1
我发现这个解决方案。它适用于 CentOS，而不是 Ubuntu，但它可以工作。它说
在此处复制配置：/etc/openvpn 并更改配置中文件的路径以进行更正。
我不确定你应该在哪里“更改路径”，它可能是WorkingDirectory服务文件中的（）。/usr/lib/systemd/system/[email protected]
您已经尝试将配置文件放入/etc/openvpn/，所以也许您也只需要调整服务文件。
注意：我认为仅复制server.conf.我认为其他文件（例如ca.crt）也是需要的，因为它们被server.conf.
该指南有错误吗？
但是，这种解决方法不是必需的。我在虚拟机中创建了全新的 Ubuntu 22.04 安装，并按照指南进行操作直到步骤 10。我没有单独的 CA 服务器，但这不会对当前问题产生影响。
现在你猜怎么着？在步骤 10 中，服务器启动，没有出现任何错误。这并不能解决你的问题。但至少现在您知道本指南可能是正确的，而问题是由其他原因引起的。
目录和文件权限
你说一切都井井有条，有访问权限。为了确定起见，我将写下我的工作设置的权限：
- 目录
/etc/、/etc/openvpn/和/etc/openvpn/server/属于 ，root:root并被 chmod 为755。 - 中的文件
/etc/openvpn/server/属于 并被root:rootchmod 为600，只是server.conf设置为644。
答案2
在我的例子中，当 nginx 首先启动时导致 vpn 错误
如果您使用 nginx 作为 VPN 客户端的反向代理，请执行以下操作：
sudo su
#stop open vpn and nginx
systemctl stop openvpn
systemctl stop nginx
#re-start openvpn first
systemctl start openvpn
systemctl status openvpn
#finally restart your nginx service
systemctl start nginx
systemctl status nginx