I want to combine Internet speed from multiple sources(datcard, wifi, landline cable) on Ubuntu.
Is there any software just like connectify dispatcher does on Windows for Ubuntu?
You can use dispatch proxy. While it lacks the shiny UI of connectify, it lets you use multiple interfaces, prefer one interface over another and load balance to an extent. It will work best with multiple threads (The maximum speed of any one connection is the maximum speed of the interface its using - something like axel will be a lot faster than say wget.). It works as a proxy and whatever software you use with it needs to be able to work with a proxy. You can also run this on one system, and allow other systems on the lan to connect to it.