"Peer authentication" means that it's comparing your database username against your Linux username. It should work if you're logged in as ​​postgres​​. You probably don't want to hit that ​​md5​​ rule in ​​pg_hba​​, as the ​​postgres​​ database user generally doesn't have a password. –

 

The Problem you have is, that if u dont define the Host, your system will decide.

explicit add "-h localhost", this will fix it