ES Client error

ES Client command line:
    --node.name=proxy1 \
    --node.data=false \
    --node.master=false \
    --network.host=${COREOS_PRIVATE_IPV4} \
    --discovery.zen.ping.multicast.enabled=false \
    --discovery.zen.ping.unicast.hosts=$UNICAST_HOSTS'

- cluster_name is set via elasticsearch.yml

Log output:
Apr 08 17:58:05 ip-10-183-2-182.ec2.internal bash[13169]: [2015-04-08 17:58:05,367][INFO ][discovery                ] [proxy1] es01/7SsGhSVUR5y-Ls3s2yyeSw
Apr 08 17:58:08 ip-10-183-2-182.ec2.internal bash[13169]: [2015-04-08 17:58:08,563][INFO ][discovery.zen            ] [proxy1] failed to send join request to master [[ip-10-183-2-55.ec2.internal][2tst-FQKQMG6R8PMeJ-i6g][81246b06e29b][inet[/10.183.2.55:9300]]], reason [RemoteTransportException[[ip-10-183-2-55.ec2.internal][inet[/172.17.0.60:9300]][internal:discovery/zen/join]]; nested: ConnectTransportException[[proxy1][inet[/10.183.2.182:9300]] connect_timeout[30s]]; nested: ConnectException[Connection refused: /10.183.2.182:9300]; ]