Logstash cmd displaying wrong output

[anushka1203]

Hi, I am new to ELK stack and I am trying to test out parsing sample syslog messages by following the steps mentioned on the official website --
https://www.elastic.co/guide/en/logstash/current/config-examples.html#_processing_syslog_messages

This is my config file

input {
  tcp {
    port => 5000
    type => syslog
  }
}

filter {
  if [type] == "syslog" {
  grok {
    match => { "message" => "%{SYSLOGTIMESTAMP:syslog_timestamp} %{SYSLOGHOST:syslog_hostname} %{DATA:syslog_program}(?:\[%{POSINT:syslog_pid}\])?: %{GREEDYDATA:syslog_message}" }
    add_field => [ "received_at", "%{@timestamp}" ]
    add_field => [ "received_from", "%{host}" ]
  }
  date {
    match => [ "syslog_timestamp", "MMM  d HH:mm:ss", "MMM dd HH:mm:ss" ]
   }
  }
}

output {
  elasticsearch { # output to ES
    hosts => [ "localhost:9200" ]
    index => "indexforsyslog1"
  }
  stdout { codec =>  "rubydebug" }
}

after I use telnet client and paste the sample syslog messages (given on website), I receive the following output on original logstash cell

{
          "tags" => [
        [0] "_grokparsefailure"
    ],
       "message" => "\u0016\r",
          "port" => 50792,
          "type" => "syslog",
      "@version" => "1",
          "host" => "0:0:0:0:0:0:0:1",
    "@timestamp" => 2022-02-11T06:38:56.126Z
}

I need help in figuring out why this happens and how to solve it to get the right output. Please help