No i have not try IPv6 . I don't know related or not but i also have following configs echo 1025 65000 > /proc/sys/net/ipv4/ip_local_port_range echo 0 > /proc/sys/net/ipv4/tcp_syncookies echo 131072 > /proc/sys/net/ipv4/tcp_max_syn_backlog echo 1 > /proc/sys/net/ipv4/ip_forward echo 0 > /proc/sys/net/ipv4/conf/lo/rp_filter echo 1 > /proc/sys/net/ipv4/ip_forward echo 2 > /proc/sys/net/ipv4/conf/default/rp_filter echo 2 > /proc/sys/net/ipv4/conf/all/rp_filter echo 0 > /proc/sys/net/ipv4/conf/p2p1/rp_filter echo 524288 > /proc/sys/net/netfilter/nf_conntrack_max and enabled/disabled following #echo 0 > /proc/sys/net/ipv4/tcp_window_scaling #echo 0 > /proc/sys/net/ipv4/tcp_ecn Here is route rules /sbin/iptables -t mangle -N DIVERT /sbin/iptables -t mangle -A DIVERT -j MARK --set-mark 1 /sbin/iptables -t mangle -A DIVERT -j ACCEPT /sbin/iptables -t mangle -A PREROUTING -p tcp -m socket -j DIVERT /sbin/iptables -t mangle -A PREROUTING -p tcp --dport 80 -j TPROXY --tproxy-mark 0x1/0x1 --on-port 3129 ip rule add fwmark 1 lookup 100 ip route add local 0.0.0.0/0 dev lo table 100 *Connection to providers is over GRE Tunnel .* -- View this message in context: http://squid-web-proxy-cache.1019090.n4.nabble.com/Squid-transparent-proxy-connection-fails-on-specific-sites-tp4658746p4658826.html Sent from the Squid - Users mailing list archive at Nabble.com.