Note that tncfg is only supported on the classic KLIPS stack. It is not supported on any other stack and will be completely removed in future versions. A replacement command still needs to be designed
The historical use of tncfg is to attach/detach IPsec virtual interfaces (e.g. ipsec0) to/from physical interfaces (e.g. eth0) through which packets will be forwarded once processed by KLIPS.
The modern use of tncfg is to create and delete virtual interfaces known as mastXXX. mast stands for Mooring and XXX.
The form with no additional arguments lists the contents of /proc/net/ipsec_tncfg. The format of /proc/net/ipsec_tncfg is discussed in ipsec_tncfg(5).
The --attach form attaches the virtual interface to the physical one.
The --detach form detaches the virtual interface from whichever physical interface it is attached to.
The --clear form clears all the virtual interfaces from whichever physical interfaces they were attached to.
Virtual interfaces typically have names like ipsec0 or mast0 while physical interfaces typically have names like eth0 or ppp0.
ipsec tncfg --create mast12
ipsec tncfg --create ipsec4
ipsec tncfg --attach --virtual ipsec0 --physical eth0
ipsec(8), ipsec_manual(8), ipsec_eroute(8), ipsec_spi(8), ipsec_spigrp(8), ipsec_klipsdebug(8), ipsec_tncfg(5)
Written for the Linux FreeS/WAN project <m[blue]http://www.freeswan.org/m> by Richard Guy Briggs.