Netfilter iptables Log Message Codes

IN = Input interface
OUT = Output interface
MAC = Ethernet hardware address (aka MAC address)
SRC = Source IP address
DST = Destination IP address
LEN = Packet length
TOS = Type of Service (for packet prioritization)
PREC = Precedent bits
TTL = Time to Live
ID = Packet identifier
PROTO = Protocol (eg. TCP, UDP)
SPT = Source port
DPT = Destination port
WINDOW = Size of TCP window
RES = Reserved bits
ACK = Acknowledge bit set
URGP = Urgent packet

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