If you are not a developer, you probably do not need this.
Cycript CYListenServer on port 8556 for iOS 11.
Utilizing a standard tweak, an executable and a bash script, when combined with the official version of Cycript (plus Electra entitlement signatures), cyrun allows Cycript to be loaded into most Apps/Processes on your device. It uses Cycript's built in CYListenServer at 127.0.0.1:8556, so only one instance can be running at a time.
You will probably need to manually install the official version of Cycript since Saurik's repo is not available in Cydia on iOS 11.