Troubleshooting client VPN tunnel connectivity

Purpose of this troubleshooting page

This page is specifically about attempting to find and resolve problems with an OpenVPN client program failing to connect to an OpenVPN Access Server. It does not deal with problems in reaching a target system over the established VPN tunnel once the VPN tunnel is already working. That is handled in a separate page: troubleshooting reaching systems over the VPN tunnel.

So if for example you start the OpenVPN client connection and it issues an error and disconnects you, then the information here should help you in determining a possible cause and solution. If not, reach out to us on the support ticket system and provide as much detail as you can.

Locating the server log files

To diagnose problems with an OpenVPN server or client, it is helpful to look at the log files. The log files are located in specific areas on your computer systems, and the following is a general guide on how to find them and how to get the best information out of them. Log files are the place to check whenever you're having any problems making a connection with an OpenVPN client program to the OpenVPN Access Server, they the information needed to ascertain what's going wrong.

On the OpenVPN Access Server there is the server side log:
(in case of a failover setup)

In the event that you are having problems with starting the Access Server or certain portions of it, for example the web services, then it may be useful to stop the Access Server service, move the log file aside, then start the Access Server service, and stop it again immediately. This creates a new clean log file that contains the startup and shutdown sequence of the Access Server and no other extraneous information. This makes analysis of the log file much easier. To do so use these commands in order:

service openvpnas stop
mv /var/log/openvpnas.log /var/log/openvpnas.log.old
service openvpnas start
service openvpnas stop

You can then grab the /var/log/openvpnas.log file for analysis and start the Access Server again:

service openvpnas start

Locating the client log files

Log file location for the OpenVPN Connect Client for Windows:
C:\Program Files (x86)\OpenVPN Technologies\OpenVPN Client\etc\log\openvpn_(unique_name).log

The OpenVPN Connect Client for Mac:
/Library/Application Support/OpenVPN/log/openvpn_(unique_name).log

Macintosh may not show you this folder in finder as it only shows you certain things and hides others. So to get to the /Library folder, open Finder and in the menu at the top choose Go followed by Go to folder and then enter the path /Library to get into that directory. You can then go to the correct folder and look up the log file. Please also note that the OpenVPN Connect Client for Macintosh will have permissions set on the log file so that you cannot normally open it. To bypass this, right click the log file and choose the Get info option in the menu. Then at the bottom, under Sharing & Permissions, you will be able to use the yellow padlock icon to unlock the settings and to give everyone read access. Then you will be able to open the log file with a right click and selecting Open with and then choosing something like Text editor to view the contents of the log file.

Known error messages and possible solutions

TLS Error: TLS key negotiation failed to occur within 60 seconds (check your network connectivity)
This particular error can have multiple different causes as it is a fairly generic error message.

A possible explanation is that the client program is old and supports only TLS 1.0, but the server is expecting TLS level 1.1 or higher. To see if this is the case log on to the server and check the server side log file. The chances are high that your client program is an older version, like version 2.2 or older, and that it doesn't know how to handle a modern TLS minimum level requirement, when you see messages that look like this on the server side:

OpenSSL: error:140760FC:SSL routines:SSL23_GET_CLIENT_HELLO:unknown protocol'
TLS_ERROR: BIO read tls_read_plaintext error'
TLS Error: TLS object -> incoming plaintext read error'
TLS Error: TLS handshake failed'
SIGUSR1[soft,tls-error] received, client-instance restarting'

The solution to this particular problem is to upgrade the client software to the latest version.

Another possible explanation is that the settings regarding TLS minimum requirement level have been altered but the OpenVPN client is using an older copy of the connection profile which has incorrect instructions. The settings on the client and the server must match for the connection to be successful. In this situation installing a new copy of the configuration profile will solve the issue. A complete uninstall, redownload, and reinstall of the OpenVPN Connect Client should take care of that for you.

And yet another possible explanation is that there is a blockade in place in a firewall or at the Internet service provider that is blocking or interfering with the TLS handshake in some way.

Server poll timeout
One of the very first steps that an OpenVPN client program will do when trying to connect to an OpenVPN Access Server is to simply send out a message requesting for a reply. So basically a "hello are you there?" message. The server is then supposed to respond and then a connection is started. However if you see a server poll timeout error message then the server could not be reached at the specified port. Why this is not possible is another question entirely, but the error message is very clear: there is simply no response at all on that address and port. So when you see this message it would be good to check if the port is actually open, if the port is correct, if the address you're trying to reach can actually be reached from the Internet, and isn't a private IP address only, and other such checks to confirm basic connectivity to the server. At this point you're not even looking at a problem that has anything to do with the OpenVPN protocol itself. This is a most basic "this server cannot be reached" message.

A common mistake that is made is that people set up the Access Server on a private IP address but neglect to set up a proper FQDN DNS name for it, and configure that FQDN DNS name in the Admin UI under Server Network Settings in the Host name or IP address field. It is that field value that connection profiles generated and provisioned to the OpenVPN clients will be using to start a connection to. So if this is set to an internal private IP address that the Access Server was installed on, then the connection profiles will try to connect to that private IP address, which is unlikely to be reachable from anywhere else but the internal network that the Access Server itself is on. The solution is to set up a proper DNS name and configure that and save settings. Then uninstall, redownload, and reinstall the connection profile or OpenVPN Connect Client program and to try again.

Another common mistake is to forget to open the 3 ports required for OpenVPN Access Server to be reachable properly. By default these are TCP 443, TCP 943, and UDP 1194.

SESSION_ID only allowed to be used by client IP address that created it
OpenVPN Access Server uses a session-based-token system for server-locked and user-locked profiles. Auto-login type profiles don't. What this means is that after a user authenticates successfully, they are given a session token to identify themselves with. Compare it to going to a party and you show up and pay your entry fees, and if you need to go out for a little bit, they give you a stamp on the back of your hand, or put a paper/plastic strip around your wrist, so that you can show up again later and be admitted access again. That's a very simplified explanation. With a session token, each token is unique and uniquely identifies you. This avoids having to store your credentials in memory or bothering the user to reauthenticate when you temporarily lose contact with the server and reconnect again, so it's safer and more convenient. The session token is locked to the IP address that the original authentication attempt was made from, this is a security feature. When you see this message it means the session token your client program offered to the server was generated originally from another IP address. This can happen for example if you switch Internet connection, like logging in at work, then moving your laptop home and it tries to reconnect automatically with the session token. This session token IP lock is a security feature that can be disabled to allow such automatic reconnects to occur without this error message.

See also the topic authentication problems for more possible error messages and solutions regarding authentication issues.