You can install Apple Network Link Conditioner
In Yosemite:
Network Link Conditioner can be found in the "IO Tools for Xcode Hardware" package. This can be downloaded from the Apple Developer Download Page . Once the download is complete, open the DMG and double-click "Network Link Condition.prefPane" to install ( source ).
Using this settings panel, you can create a profile at a speed of 0 Kbps.

In older versions of OSX:
Mountain Lion / Mavericks: Xcode > Open Developer Tool > More Developer Tools
Leo: /Developer/Applications/Utilities/Network Link Conditioner
Tieme Mar 09 2018-12-12T00: 00Z
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