On a windows 7 enterprise host (behind a proxy) I installed virtualbox with an ubuntu guest. Network setting is NAT. After configuring the proxy in the guest (/etc/environment and network manager) I can access the internet via browser but not in a terminal. Hence, I cannot install the guest additions and not update the os.
$ ping 188.8.131.52 PING 184.108.40.206 (220.127.116.11) 56(84) bytes of data. From 18.104.22.168 icmp_seq=1 Destination Host Unreachable
It seems others had that problem before but no one solved it.
I can, however, ping the host from the guest successfully both by ip and hostname. Any ping from the host to external, like 22.214.171.124 doesn't work either. Only internal pings to other pc's work.
What could I else try?