[vbox-dev] Virtualbox NAT and TTL mangling ISPs

Lucian Adrian Grijincu lucian.grijincu at rosedu.org
Thu Dec 3 14:31:28 GMT 2009


My ISP decided to reduce the number of computers that would connect to
their network on a single connection by mangling with the TTL of IP

For now it sets the TTL of all incoming packets to 1.
When a host receives a packet destined for a Virtualbox vm, it will first
decrement the TTL before deciding where to forward it.
Because TTL is now 1 the host will drop the packet.

This fixes it for me:
  iptables -t mangle -A POSTROUTING -j TTL --ttl-set 64
but it took me a while to come up with the fix.

It would be nice if the Virtualbox GUI or the manual would
list this work-around (or a better one if someone finds something
better) and, ideally, the GUI could provide a way to enable non
experienced users to run this command automagically.

..: Lucian

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