what the "!" means in the following iptable rule
iptables -I inacc ! -i br0 -p UDP --dport 69 -j ACCEPT
I think is related to the interface
br0. I think it mean any interface except the
Am I correct?
Yes, you are. From "man iptables"
[!] -i, --in-interface name Name of an interface via which a packet was received (only for packets entering the INPUT, FORWARD and PREROUTING chains). When the "!" argument is used before the interface name, the sense is inverted. If the interface name ends in a "+", then any interface which begins with this name will match. If this option is omitted, any interface name will match.