At some customers or with some friends' adsl connection I have been puzzled to see that I could perfectly surf the web with IE or firefox from a bridged Windows VM but coud not open any site from my linux host.
Recently I was lucky to met a linux guru that explained me why!
This seems to be related to TCP windows scaling .
To fix the problem it is enought to turn it off by doing this as root:
[root@poldon ~]# cd /proc/sys/net/ipv4
[root@poldon ipv4]# echo "0" > tcp_window_scaling
Then edit /etc/sysctl.conf and add a line "net.ipv4.tcp_window_scaling = 0" to make the option persistant across reboots.
Many thanks to Graziano for pointing this out to me!