How to reconnect VPN by using Tunnelblick from command line

Your best bet seems to be AppleScript:

tell application "System Events"
   tell current location of network preferences
       set VPNservice to service "VPN (L2TP) 2" -- name of the VPN service
       if exists VPNservice then connect VPNservice
   end tell
end tell

(from http://macscripter.net/viewtopic.php?id=22992)

As for entering a username and password, I'm not sure how you could do that. Further scripting could get you the frontmost window and input the username and password, then submit the dialog, but as I don't have a Cisco VPN to test I couldn't tell you how to set that up.

If you have the actual Cisco VPN client installed (which afaik is not necessary), you could just use this command:

open /Applications/VPNClient.app --args -c -user <YourUsername> -pwd <YourPassword> <ProfileNameToConnect>

I had the same problem on my Mac, and after fixing it I have figured out that it was caused by FortiClient (VPN client). Even when FortiClient was disconnected - it's DNS still appeared in the scutil.

The solution for me was:

scutil
> list ".*DNS"

This will show you a list of all DNS configs, that will look something like:

subKey [0] = State:/Network/Global/DNS <br>
subKey [1] = State:/Network/MulticastDNS<br>
subKey [2] = State:/Network/OpenVPN/DNS<br>
subKey [3] = State:/Network/OpenVPN/OldDNS<br>
subKey [4] = State:/Network/PrivateDNS<br>
subKey [5] = State:/Network/Service/forticlientsslvpn/DNS <br>

To check each of them run: (until you find the problematic one)

> get key_name
> d.show

…and to fix it run:

> get key_name
> d.remove ServerAddresses
> set key_name

This is how it looked on my machine:

> get State:/Network/Service/forticlientsslvpn/DNS 
> d.show
<dictionary> {
  ServerAddresses : <array> {
    0 : 192.168.30.6
    1 : 192.168.30.15
  }
  SupplementalMatchDomains : <array> {
    0 :
  }
  SupplementalMatchOrders : <array> {
    0 : 100000
  }
}
> d.remove ServerAddresses
> d.show
<dictionary> {
  SupplementalMatchDomains : <array> {
    0 :
  }
  SupplementalMatchOrders : <array> {
    0 : 100000
  }
}
> set State:/Network/Service/forticlientsslvpn/DNS
> exit