我安装和configurationl7-filter：
sudo apt-get install l7-filter-userspace l7-protocols sudo cp /usr/share/doc/l7-filter-userspace/examples/sample-l7-filter.conf /etc/l7-filter.conf sudo l7-filter -f /etc/l7-filter.conf -q 2 -v sudo iptables -t mangle -A PREROUTING -j NFQUEUE --queue-num 2 sudo iptables -t mangle -A OUTPUT -j NFQUEUE --queue-num 2 l7-filter加载所有的协议，不会给出错误：
Got packet, had no ct: udp 17 src=192.168.1.1 dst=8.8.8.8 sport=45659 dport=53 Got packet, had no ct: udp 17 src=192.168.1.1 dst=8.8.8.8 sport=34234 dport=53
尝试加载ip_conntrack_netlink和nf_conntrack_ipv4模块：
sudo modprobe ip_conntrack_netlink sudo modprobe nf_conntrack_ipv4