Jacob - 2012-06-04

Slirp 1.0.17 with FULL_BOLT is being used to tunnel traffic much like a VPN using only userspace on the server.  This is accomplished using either socat or ssh to transport PPP over TCP.  An obvious problem is that we are using TCP over TCP.

For some reason, each TCP connection over the tunnel is limited to ~30k, but multiple connections can saturate the link.  Can anyone offer any insight as to why this happens?  I believe that this may be due to TCP over TCP, but OpenVPN does not have this problem with TCP over TCP, so there must be a solution.

Socat UDP was attempted as a transport for PPP.  Connection is possible, but performance is dismal.  It would be really cool to add TUN emulation to slirp so we could sidestep any issues with PPP.  I will dive into the code if anyone can offer any insight or interest.