ssh -L 3307:d.local.internal.com:3306 ubuntu@d.local.internal.com

con <- dbConnect(RMySQL::MySQL(), host = "127.0.0.1", user = "root", password = "pass", port=3307)

Error in .local(drv, ...) : Failed to connect to database: Error: Can't connect to MySQL server on '127.0.0.1' (57)