logstash syslog config with support of rfc3164 and rfc5424 (using different port)

logstash.conf

input {
    syslog {
        id => "syslog_rfc3164"
        port => 1514
    }
    syslog {
        id => "syslog_rfc5424"
        port => 1515
        grok_pattern => "%{SYSLOG5424LINE}"
        tags => [ "rfc5424" ]
    }
}

filter {
    if "rfc5424" in [tags] {
        mutate {
            remove_field => ["system"]
        }
    }
}