title: what is the multicast doing on 224.0.0.251?
body: <p>On my debian server (squeeze) I get this message every few seconds:</p>
  
  <blockquote>
    <p>Sep 18 21:28:14 myhost kernel: [7903784.720091] AIF:UNPRIV connect
    attempt: IN=eth0 OUT= MAC= SRC=<strong>my_serverip_eth0</strong> DST=224.0.0.251
    LEN=72 TOS=0x00 PREC=0x00 TTL=255 ID=0 DF PROTO=UDP SPT=5353 DPT=5353
    LEN=52</p>
  </blockquote>
  
  <p>the packets are coming from inside my server (i replaced it with <strong>my_serverip_eth0</strong>) and seem to be blocked going out to the destination 224.0.0.251.</p>
  
  <p>So some task inside my server is contacting 224.0.0.251 and this is blocked by my <code>arnos_firewall</code>.</p>
  
  <p>How can I find out who or which task is trying to do that and if it is useful or not?</p>
  
  <p>And if I don't need it, how can I suppress that message then?</p>