iodine

tool for tunneling IPv4 data through a DNS server
This is a piece of software that lets you tunnel IPv4 data through a DNS
server. This can be usable in different situations where internet access is
firewalled, but DNS queries are allowed.
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iodine is similar to nstx but has password authentication, brings up the
tun interface automatically and lets the user specify the IP address as a
command line option.