transbind

Enable transparent binding on applications that don't allow it natively.

This library is still experimental. It is based on LD_PRELOAD to set socket options before any bind() calls.

• For IPv4 : IP_TRANSPARENT or IP_FREEBIND
• For IPv6 : IPV6_TRANSPARENT

How To

LD_PRELOAD=<installation path>/transbind.so <server application>

The environment variable TRANSBIND_VERBOSITY allows to enable/disable debug messages. A value greater than 0 will enable debug messages. The default is to not log anything.

Tested applications (IPv4 only)

• nginx
• varnish

Side notes

iptables -t mangle -N DIVERT
iptables -t mangle -A PREROUTING -p tcp -m socket -j DIVERT
iptables -t mangle -A DIVERT -j MARK --set-mark 1
iptables -t mangle -A DIVERT -j ACCEPT

ip rule add fwmark 1 lookup 100
ip route add local 0.0.0.0/0 dev lo table 100

iptables -t mangle -A PREROUTING -p tcp --dport <port> -j TPROXY --tproxy-mark 0x1/0x1 --on-port <port>