求助：编译问题

系统装了ucd-snmp－4.2.3，利用它的API编了个简单的程序，从agent取系统描述。
使用下面的命令编译：
gcc -g -I/usr/local/include -o snmpapp snmpapp.c -L/usr/local/lib -lsnmp
系统提示错误信息如下：
/usr/local/lib/libsnmp.a(keytools.o): In function `generate_Ku\':
/usr/local/ucd-snmp/snmplib/keytools.c:124: undefined reference to `EVP_md5\'
/usr/local/ucd-snmp/snmplib/keytools.c:126: undefined reference to `EVP_sha1\'
/usr/local/ucd-snmp/snmplib/keytools.c:126: undefined reference to `EVP_DigestInit\'
/usr/local/ucd-snmp/snmplib/keytools.c:141: undefined reference to `EVP_DigestUpdate\'
/usr/local/ucd-snmp/snmplib/keytools.c:153: undefined reference to `EVP_DigestFinal\'
/usr/local/lib/libsnmp.a(scapi.o): In function `sc_random\':
/usr/local/ucd-snmp/snmplib/scapi.c:150: undefined reference to `RAND_bytes\'
/usr/local/lib/libsnmp.a(scapi.o): In function `sc_generate_keyed_hash\':
/usr/local/ucd-snmp/snmplib/scapi.c:255: undefined reference to `EVP_md5\'
/usr/local/ucd-snmp/snmplib/scapi.c:258: undefined reference to `EVP_sha1\'
/usr/local/ucd-snmp/snmplib/scapi.c:258: undefined reference to `HMAC\'
/usr/local/lib/libsnmp.a(scapi.o): In function `sc_hash\':
/usr/local/ucd-snmp/snmplib/scapi.c:345: undefined reference to `EVP_md5\'
/usr/local/ucd-snmp/snmplib/scapi.c:348: undefined reference to `EVP_sha1\'
/usr/local/ucd-snmp/snmplib/scapi.c:348: undefined reference to `EVP_DigestInit\'
/usr/local/ucd-snmp/snmplib/scapi.c:353: undefined reference to `EVP_DigestUpdate\'
/usr/local/ucd-snmp/snmplib/scapi.c:354: undefined reference to `EVP_DigestFinal\'
/usr/local/lib/libsnmp.a(scapi.o): In function `sc_encrypt\':
/usr/local/ucd-snmp/snmplib/scapi.c:592: undefined reference to `des_key_sched\'
/usr/local/ucd-snmp/snmplib/scapi.c:596: undefined reference to `des_ncbc_encrypt\'
/usr/local/ucd-snmp/snmplib/scapi.c:600: undefined reference to `des_ncbc_encrypt\'
/usr/local/lib/libsnmp.a(scapi.o): In function `sc_decrypt\':
/usr/local/ucd-snmp/snmplib/scapi.c:715: undefined reference to `des_key_sched\'
/usr/local/ucd-snmp/snmplib/scapi.c:718: undefined reference to `des_cbc_encrypt\'
collect2: ld returned 1 exit status

是什么问题？？