Using SOCKS 4/5 proxy is no easy task:
- a machine may well be able to reach the proxy, even if it is not on the same sub-net(s) as the machine itself (absolutely legitimate)
- tsocks.conf needs a list of so-called 'local' networks that can be reached without the need for a SOCKS connection
- SOCKS proxies are expected to be in 'local' networks
- there is absolutely NO way to tell what networks are local, besides the sub-net(s) the machine is in
Therefore, appropriate configuration of SOCKS 4/5 configuration is really complex, and attempts to correctly overcome this issue are doomed.