Stock ipsec-tools v0.7 does not build in RedHat EL 4:
Making all in racoon
make[3]: Entering directory `/home/octeon/src/ipsec-tools-0.7/src/racoon’
if gcc -DHAVE_CONFIG_H -I. -I. -I../.. -I./../libipsec -D_GNU_SOURCE -include ./src/include-glibc/glibc-bugs.h -I./src/include-glibc -I./src/include-glibc -I./../../src/racoon/missing -D_GNU_SOURCE -include ../../src/include-glibc/glibc-bugs.h -I../../src/include-glibc -I../../src/include-glibc -DSYSCONFDIR=\”/usr/local/etc\” -DADMINPORTDIR=\”/usr/local/var/racoon\” -g -O2 -Wall -Werror -Wno-unused -MT isakmp.o -MD -MP -MF “.deps/isakmp.Tpo” -c -o isakmp.o isakmp.c; \
then [...]