OpenVPN fatal error on centos 7

biologist

Hello. I've installed and configured openvpn on my centos 7 vps server but when I try to start the service I got these errors:

/sbin/ip addr add dev tun0 10.8.0.1/24 broadcast 10.8.0.255
Could not determine IPv4/IPv6 protocol. Using AF_INET
Socket Buffers: R=[212992->212992] S=[212992->212992]
TCP/UDP: Socket bind failed on local address [AF_INET][undef]:1194: Address already...(errno=98)
Exiting due to fatal error
Closing TUN/TAP interface
/sbin/ip addr del dev tun0 10.8.0.1/24
openvpn@server.service: main process exited, code=exited, status=1/FAILURE
Unit openvpn@server.service entered failed state.
openvpn@server.service failed.

Here is my server.conf file:

port 1194
proto udp
dev tun
ca ca.crt
cert server.crt
key server.key  # This file should be kept secret
dh dh2048.pem
topology subnet
remote-cert-eku "TLS Web Client Authentication"
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
keepalive 10 120
;tls-auth ta.key 0 # This file is secret
tls-crypt myvpn.tlsauth
cipher AES-256-CBC
max-clients 100
user nobody
group nobody
persist-key
persist-tun
status openvpn-status.log
verb 3
explicit-exit-notify 1

and here is the result for lsof -i command:

COMMAND     PID       USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
systemd       1       root   29u  IPv6  14615      0t0  TCP *:sunrpc (LISTEN)
systemd       1       root   30u  IPv4  14616      0t0  TCP *:sunrpc (LISTEN)
avahi-dae   670      avahi   12u  IPv4  16188      0t0  UDP *:mdns
avahi-dae   670      avahi   13u  IPv4  16189      0t0  UDP *:59478
chronyd     685     chrony    1u  IPv4  16062      0t0  UDP localhost:323
chronyd     685     chrony    2u  IPv6  16063      0t0  UDP localhost:323
sshd       1033       root    3u  IPv4  18691      0t0  TCP *:ssh (LISTEN)
sshd       1033       root    4u  IPv6  18700      0t0  TCP *:ssh (LISTEN)
master     1148       root   13u  IPv4  19428      0t0  TCP localhost:smtp (LISTEN)
master     1148       root   14u  IPv6  19429      0t0  TCP localhost:smtp (LISTEN)
python     1157 openvpn_as    7u  IPv4  19867      0t0  TCP static.213.239.4.46.clients.your-server.de:943 (LISTEN)
python     1157 openvpn_as    9u  IPv4  19868      0t0  TCP localhost:904 (LISTEN)
python     1157 openvpn_as   10u  IPv4  19869      0t0  TCP localhost:905 (LISTEN)
python     1157 openvpn_as   11u  IPv4  19870      0t0  TCP localhost:906 (LISTEN)
python     1157 openvpn_as   13u  IPv4  19871      0t0  TCP localhost:907 (LISTEN)
python     1157 openvpn_as   14u  IPv4  19872      0t0  TCP localhost:908 (LISTEN)
python     1157 openvpn_as   15u  IPv4  19873      0t0  TCP localhost:909 (LISTEN)
openvpn-o  1175 openvpn_as    5u  IPv4  20032      0t0  TCP static.213.239.4.46.clients.your-server.de:https (LISTEN)
openvpn-o  1189 openvpn_as    5u  IPv4  20114      0t0  UDP static.213.239.4.46.clients.your-server.de:openvpn
sshd      22533       root    3u  IPv4 169408      0t0  TCP static.213.239.4.46.clients.your-server.de:ssh->188.166.118.182:51888 (ESTABLISHED)
sshd      27613       root    3u  IPv4 253895      0t0  TCP static.213.239.4.46.clients.your-server.de:ssh->188.166.118.182:21987 (ESTABLISHED)

Thank you so much.

bbuckm

TCP/UDP: Socket bind failed on local address [AF_INET][undef]:1194: Address already...(errno=98)

It looks like you are trying to bind it to port 1194 twice. Try restarting rather than starting twice.

biologist

bbuckm wrote

TCP/UDP: Socket bind failed on local address [AF_INET][undef]:1194: Address already...(errno=98)

It looks like you are trying to bind it to port 1194 twice. Try restarting rather than starting twice.

I've restarted openvpn service with

sudo systemctl restart openvpn@server.service

and then get following result after runnin

sudo systemctl status openvpn@server.service

Still same result.

bbuckm

There must be something else listening on port 1194. What is that Python process owned by openvpn_as? And what is that openvpn-o process? Is there other stuff running on that same machine? What is the output of

sudo netstat -tulpn

biologist

bbuckm wrote There must be something else listening on port 1194. What is that Python process owned by openvpn_as? And what is that openvpn-o process? Is there other stuff running on that same machine? What is the output of
sudo netstat -tulpn
?

The output for

sudo netstat -tulpn

is:

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State             PID/Program name
tcp        0      0 127.0.0.1:904           0.0.0.0:*               LISTEN            1157/python
tcp        0      0 127.0.0.1:905           0.0.0.0:*               LISTEN            1157/python
tcp        0      0 127.0.0.1:906           0.0.0.0:*               LISTEN            1157/python
tcp        0      0 127.0.0.1:907           0.0.0.0:*               LISTEN            1157/python
tcp        0      0 127.0.0.1:908           0.0.0.0:*               LISTEN            1157/python
tcp        0      0 127.0.0.1:909           0.0.0.0:*               LISTEN            1157/python
tcp        0      0 46.4.239.213:943        0.0.0.0:*               LISTEN            1157/python
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN            1/systemd
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN            1033/sshd
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN            1148/master
tcp        0      0 46.4.239.213:443        0.0.0.0:*               LISTEN            1175/openvpn-openss
tcp6       0      0 :::111                  :::*                    LISTEN            1/systemd
tcp6       0      0 :::22                   :::*                    LISTEN            1033/sshd
tcp6       0      0 ::1:25                  :::*                    LISTEN            1148/master
udp        0      0 0.0.0.0:59478           0.0.0.0:*                                 670/avahi-daemon: r
udp        0      0 46.4.239.213:1194       0.0.0.0:*                                 1189/openvpn-openss
udp        0      0 0.0.0.0:5353            0.0.0.0:*                                 670/avahi-daemon: r
udp        0      0 127.0.0.1:323           0.0.0.0:*                                 685/chronyd
udp6       0      0 ::1:323                 :::*                                      685/chronyd

bbuckm

What is that openvpn-openss on port 443/tcp and port 1194/udp? Really you should find out what it is, stop and disable it. As a sledgehammer approach, you could always kill processes 1175 and 1189, but that is not an ideal solution.

biologist

bbuckm wrote What is that openvpn-openss on port 443/tcp and port 1194/udp? Really you should find out what it is, stop and disable it. As a sledgehammer approach, you could always kill processes 1175 and 1189, but that is not an ideal solution.

I have no idea what is it. But as you recommended I've killed PID 1175 & 1189 but still same errors are happening.

bbuckm

It almost looks like OpenVPN and OpenVPN Access Server are running at the same time on the same server.

biologist

Thanks. I'll remove it and post result here

biologist

bbuckm wrote It almost looks like OpenVPN and OpenVPN Access Server are running at the same time on the same server.

Thank you so much. You are my hero. I've removed AS with

sudo yum remove openvpn-as

and now service is running. Thank you again 🙂

bbuckm

Yay! Well done.