Don't forget it's userspace equiv (strace is syscalls), ltrace. This tracks all lib calls made by process.

Under windows, strace is an SSL/TLS monitoring tool (also hella useful). It shows payloads passed to CryptoAPI/CNG libs so you can easily troubleshoot explicitly encrypted protocols like ldaps. Especially useful if you use client authenticated TLS where is is not possible to use a TLS mitm proxy to snoop the layer 7 data.