library(RPostgreSQL)
drv <- dbDriver("PostgreSQL")
con <- dbConnect(drv,
                 host = "XXXXXXXX.us-east-1.redshift.amazonaws.com",
                 port = 5439,
                 user = "XXXXXXXX",
                 password = "XXXXXXXX",
                 dbname = "db1")

> Error in postgresqlNewConnection(drv, ...) :
    RS-DBI driver: (could not connect XXXXXXXX@XXXXXXXX.us-east-1.redshift.amazonaws.com on dbname "db1")

sysname                                              Linux
release                                  3.13.0-48-generic
version        #80-Ubuntu SMP Thu Mar 12 11:16:15 UTC 2015
nodename                                   ip-xx-xxx-xx-xx
machine                                             x86_64
login                                              unknown
user                                                  bcui
effective_user                                        bcui

sysname                                             Darwin
release                                             15.3.0
version                      Darwin Kernel Version 15.3.0:
                             Thu Dec 10 18:40:58 PST 2015;
                       root:xnu-3248.30.4~1/RELEASE_X86_64
nodename                                    bcui-MBP.local
machine                                             x86_64
login                                                 bcui
user                                                  bcui
effective_user                                        bcui