OpenSSL and EC Libraries
OpenSSL Without Elliptic Curve Support
Some algorithms in OpenSSL library may be restricted by patent law. Due to strong coupling between the elliptic curve support Bitcoin requires and these nominally non-free algorithms, some Linux distributions (most notably Fedora) ship OpenSSL libraries with elliptic curve support disabled. Since Bitcoin depends on elliptic curve cryptography (although not on any restricted algorithms), it cannot be used with such libraries.
Fixes / Workarounds
One workaround is to compile your own OpenSSL and use this rather than the distribution package manager's library.