I obtain this row with iptables logging option:

IN= OUT=eno49 SRC= DST= LEN=196 TOS=0x00 PREC=0x00 TTL=5 ID=53310 DF PROTO=UDP SPT=9100 DPT=8100 this packet is DROPPED

I think this is a multicast connection.

Which is the rule that accept this packet?

1 Answer 1


You have to specify you want to accept multicast. For example, based on your logs :

iptables -A OUTPUT -o eno49 -p udp --dport 8100 -m pkttype --pkt-type multicast -j ACCEPT
  • '--sport 9100' is necessary?
    – karmax
    Oct 4, 2016 at 14:27
  • Nothing is necessary but -m pkttype --pkt-type multicast, I just wanted to give an accurate example. Oct 4, 2016 at 14:52

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