minimal nginx stream config, replace TARGET / LISTEN first. nginx -c PATH/to/conf

nginx.conf

worker_processes 1; master_process off; daemon off; error_log /dev/null; pid /dev/null;
load_module /usr/lib/nginx/modules/ngx_stream_module.so;
events {}
stream { upstream u { server TARGET max_fails=0; server TARGET max_fails=0; } server { listen LISTEN; proxy_pass u; }}

T=$(mktemp); [ -f $T ] && cat <<EOF >$T
blah
EOF
sed -i -e 's/TARGET//g' -e 's/LISTEN/PORT/' $T;
nginx -c $T
rm $T