OpenVPN error ERROR: Cannot ioctl TUNSETIFF tun: Operation not permitted (errno=1)
This basically means that you are running as non-root and you need to be root to create the tun0 or tap0 device on OpenVPN. You could try sudo or adding the openvpn binary to the list of sudoers.........
Linux Mint/Ubuntu/Debian Dual NICs networks problem when enabling and disabling one device
The Scenario
You have dual NICs and you disable NIC1 which uses 192.168.1.1 as its gateway. With NIC2 you enable it/connect it to another network which also has the gateway 192.168.1.1
Everything will work fine at this point.
When switching back to NIC1 even with NIC2 disabled and even unplugged, the OS basically can't pick up the new/updated ARP entry of the old device for 192.168.1.1 and perhaps thinks it is a security risk or spoof of some sorts and blocks i........
Disable linux bash proxy ENV export variable
if you type Export and see something like this:
declare -x all_proxy="socks://127.0.0.1:22000/"
Most sites assume and tell you to check your .bashrc or /etc/profile /etc/bash.bashrc which may not apply if you've unknowingly or forgot that you setup a proxy from your GUI such as Gnome.
To check in Gnome if you have a permanent proxy do the following:
System -> Settings -> Network Proxy........