hi all,
I try to install kamailio with enable TLS module, but it raise error.
when i enable module TLS and run command make all,make install, the error is :

#make install

Makefile.defs defs skipped
make[1]: Entering directory `/usr/src/kamailio-3.0.1/modules/tls'
MAIN_NAME=kamailio ./sip-router_cert.sh -d /usr/local/etc/kamailio/
hostname: Unknown host
./sip-router_cert.sh: line 142: which: command not found
Could not find openssl command
Set OPENSSL environment variable properly (see -h for more info)
make[1]: *** [install-tls-cert] Error 1
make[1]: Leaving directory `/usr/src/kamailio-3.0.1/modules/tls'
make: *** [install-modules] Error 1
[root@appliance kamailio-3.0.1]#


please help me find and fix this problem,
thanks for help me.
Beter_green.