It's messages from the kernel firewall (netfilter/iptables): someone with IP 202.70.73.167 tried to connect (witness the TCP SYN flag at the end) to your TCP port 3128 (probably squid?)
Somehow you or a colleague of you ordered the firewall to log this kind of packets... You can see the firewall rules by doing "iptables -L -v" -- "man iptables" for more info, or visit
www.netfilter.org
Greetings
nukkel