I get 'Server Connectivity' error at google webmaster tool. I suspect it is because of iptables rules that I've set to counter some DDoS attacks, thugh I'm not sure which rules could be relevant. This may also help to know that I use Varnish/nginx combo as webserver and a standard robots.txt.
Here are the iptables rules
Chain INPUT (policy ACCEPT)
target prot opt source destination
fail2ban-ssh tcp -- anywhere anywhere multiport dports ssh
DROP udp -- anywhere anywhere udp dpt:fsp
DROP tcp -- anywhere anywhere tcp flags:!FIN,SYN,RST,ACK/SYN state NEW
DROP all -f anywhere anywhere
DROP tcp -- anywhere anywhere tcp flags:FIN,SYN,RST,PSH,ACK,URG/FIN,SYN,RST,PSH,ACK,URG
DROP udp -- anywhere anywhere udp dpt:54243
DROP udp -- anywhere anywhere udp dpt:53331
DROP udp -- anywhere anywhere udp dpt:19147
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:11211
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
I appreciate your hints to resolve this.