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I am a customer of Witopia; they provide a VPN service. For the client, they license a copy of Viscosity which is a GUI front-end for openVPN. Over the past couple of days I've noticed that if Viscosity can't connect, something happens where my network connection gets hijacked; I can't ping, connect to any websites, connect to DNS… I can't do anything.

Here is a snippet of what's going on in the Console:

10/5/10 9:21:45 PM openvpn[600] Connection reset, restarting [0] 
10/5/10 9:21:45 PM openvpn[600] /Applications/Internet-Network/Viscosity.app/Contents/Resources/dnsdown.py tun0 1500 1544 10.244.0.110 10.244.0.109 restart 
10/5/10 9:21:45 PM openvpn[600] SIGUSR1[soft,connection-reset] received, process restarting 
10/5/10 9:21:45 PM openvpn[600] NOTE: the current --script-security setting may allow this configuration to call user-defined scripts 
10/5/10 9:21:45 PM openvpn[600] NOTE: --fast-io is disabled since we are not using UDP 
10/5/10 9:21:45 PM openvpn[600] Re-using SSL/TLS context 
10/5/10 9:21:45 PM openvpn[600] LZO compression initialized 
10/5/10 9:21:45 PM mDNSResponder[16] NOTE: Wide-Area Service Discovery disabled to avoid crashing defective DNS relay 192.168.1.1:53 
10/5/10 9:22:31 PM kernel dlil_output: output error retval = 37 
10/5/10 9:22:34 PM kernel dlil_output: output error retval = 37 
10/5/10 9:22:34 PM mDNSResponder[16] mDNSPlatformSendUDP sendto failed to send packet on InterfaceID 00000000 unicast/4 to 208.67.220.123:53 skt 15 error -1 errno 55 (No buffer space available) 1364468745 
10/5/10 9:22:34 PM kernel dlil_output: output error retval = 37 
10/5/10 9:22:34 PM kernel dlil_output: output error retval = 37 
10/5/10 9:22:35 PM kernel dlil_output: output error retval = 37 
10/5/10 9:22:35 PM openvpn[600] RESOLVE: Cannot resolve host address: tlsvpn.iad.witopia.net: [HOST_NOT_FOUND] The specified host is unknown. 
10/5/10 9:22:35 PM kernel dlil_output: output error retval = 37 
10/5/10 9:22:35 PM kernel dlil_output: output error retval = 37 
10/5/10 9:22:35 PM kernel dlil_output: output error retval = 37 
10/5/10 9:22:35 PM openvpn[600] RESOLVE: Cannot resolve host address: tlsvpn.iad.witopia.net: [HOST_NOT_FOUND] The specified host is unknown. 
10/5/10 9:22:35 PM kernel dlil_output: output error retval = 37 

If I did a ping, it would tell me that there would be the following message:

ping: sendto: No buffer space available

I had to reboot to get my network connection back. Does anyone know how to resolve this issue?

I am running a MacBook Intel Core Duo 1.83 GHz, MacOS X 10.5.8, Viscosity 1.0.9. Upgrading Viscosit breaks my access to Witopia servers (I don't know why, I just know it does!)

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3 Answers

The problem seems to be related to the way Viscosity is rewriting the resolv.conf file manually. The network connection is actually alive, but after dropping the VPN connection there is no resolv.conf file, and thus no way to resolve names.

If you have this problem after closing the VPN, open the 'Network' System Preferences panel, change anything (I remove a space between a comma and a DNS server IP address), and then undo the change (I put the space back). After this, click 'Apply' and the computer will magically write out a resolv.conf file again ... Presto. Fixed.

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up vote 0 down vote accepted

Somehow openvpn is hijacking my network connection: I can't get any DNS resolution and I can't connect out. My solution, to avoid rebooting, is to kill openvpn. Open Activity Monitor and filter for the openvpn process. Kill it. Now I have network access again. I hope this helps anyone that has this problem. I've seen a couple of places where people have noted that the only thing they can do is reboot.

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For us to better assist you, please gather some more information for us to analyze over.

Please open the terminal and post the output from the following commands:

$ netstat -rn
$ ifconfig -a

That will give us the routing and interface configurations.

Also, since you mentioned Viscosity is a front-end GUI for OpenVPN, it must be using OpenVPN configuration files/keys/certificates/etc.

Please find the .ovpn client configuration file on your computer and post that here as well. The client configuration file contents should look something like this:

client
dev tun
proto udp
remote remote-server 1195*
resolv-retry infinite
nobind
persist-key
persist-tun
ca ca.crt
cert server.crt
key server.key
ns-cert-type server
tls-auth ta.key 1
comp-lzo
verb 3

*For the sake of privacy for not disclosing the location of the server, please obscure this line

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