1024以前端口需要root用户来执行

在配置logstash收集rsyslog日志时，一直抱报错，tcp和udp都无法启用。使用netstat -nap |grep 514也看不到任何进程

{:timestamp=>"2017-05-12T10:27:57.597000+0800", :message=>"syslog listener died", :protocol=>:tcp, :address=>"0.0.0.0:514", :exception=>#<SocketError: initialize: name or service not known>, :backtrace=>["org/jruby/ext/socket/RubyTCPServer.java:126:in `initialize'",
"org/jruby/RubyIO.java:871:in `new'", "/opt/logstash-2.4.0/vendor/bundle/jruby/1.9/gems/logstash-input-syslog-2.0.5/lib/logstash/inputs/syslog.rb:152:in `tcp_listener'", "/opt/logstash-2.4.0/vendor/bundle/jruby/1.9/gems/logstash-input-syslog-2.0.5/lib/logstash/inputs/syslog.rb:117:in
`server'", "/opt/logstash-2.4.0/vendor/bundle/jruby/1.9/gems/logstash-input-syslog-2.0.5/lib/logstash/inputs/syslog.rb:101:in `run'"], :level=>:warn}

{:timestamp=>"2017-05-12T10:28:02.542000+0800", :message=>"syslog listener died", :protocol=>:udp, :address=>"0.0.0.0:514", :exception=>#<SocketError: bind: name or service not known>, :backtrace=>["org/jruby/ext/socket/RubyUDPSocket.java:160:in `bind'", "/opt/logstash-2.4.0/vendor/bundle/jruby/1.9/gems/logstash-input-syslog-2.0.5/lib/logstash/inputs/syslog.rb:135:in
`udp_listener'", "/opt/logstash-2.4.0/vendor/bundle/jruby/1.9/gems/logstash-input-syslog-2.0.5/lib/logstash/inputs/syslog.rb:117:in `server'", "/opt/logstash-2.4.0/vendor/bundle/jruby/1.9/gems/logstash-input-syslog-2.0.5/lib/logstash/inputs/syslog.rb:97:in
`run'"], :level=>:warn}

搜到这篇文章终于解决
http://blog.csdn.net/julykobe/article/details/44002687
使用sudo也不行，必须sudo -i切换到root用户才正常。
http://blog.csdn.net/julykobe/article/details/44002687