[ 33%] Generating conf.token.cpp
cd /home/user/shrew-2.2.1-release/obj-i486-linux-gnu/source/iked && /usr/bin/flex -d -oconf.token.cpp conf.token.ll
flex: can't open conf.token.ll
make[3]: *** [source/iked/conf.token.cpp] Error 1
make[3]: Leaving directory `/home/user/shrew-2.2.1-release/obj-i486-linux-gnu'
make[2]: *** [source/iked/CMakeFiles/iked.dir/all] Error 2
make[2]: Leaving directory `/home/user/shrew-2.2.1-release/obj-i486-linux-gnu'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/home/user/shrew-2.2.1-release/obj-i486-linux-gnu'
dh_auto_build: make -j1 returned exit code 2
make: *** [build] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2