又是一个关于UCD的问题！

我在写一个小程序，编译时遇到以下问题，
/usr/local/lib/libsnmp.so: undefined reference to `EVP_DigestInit\'
/usr/local/lib/libsnmp.so: undefined reference to `EVP_DigestFinal\'
/usr/local/lib/libsnmp.so: undefined reference to `EVP_md5\'
/usr/local/lib/libsnmp.so: undefined reference to `HMAC\'
/usr/local/lib/libsnmp.so: undefined reference to `EVP_sha1\'
/usr/local/lib/libsnmp.so: undefined reference to `des_cbc_encrypt\'
/usr/local/lib/libsnmp.so: undefined reference to `des_key_sched\'
/usr/local/lib/libsnmp.so: undefined reference to `EVP_DigestUpdate\'
/usr/local/lib/libsnmp.so: undefined reference to `RAND_bytes\'
/usr/local/lib/libsnmp.so: undefined reference to `des_ncbc_encrypt\'

请问是怎么回事啊？

谢谢回复，
对的，库是libssl.so
现在已经好了