I have been facing some problems in installing software with ubuntu software center, due to the fact that I have not been able to run no proxy for the whole system, I have tried all methods prescribed in various websites to do the same but i always get 407 Proxy Authentication Required. So I want to install synaptic package manager through source code or .deb file which can be downloaded from the internet and then installed manually. Please post the link from which the same can downloaded and also steps to install it manually. A little detail would be of great help as I am a beginner and unaware of the nuances.
As suggested in one of the answers when i download the .deb package and perform
sudo dpkg -i synaptic_0.81.2_amd64.deb in the terminal this is what happens...

I am not able to make out where there has been a mistake.