modttl 0.1 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The application is included in Internet & Network Tools. According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software.
From the developer:
modttl modifies the TTL (time to live) of outgoing packets.
You may want to check out more software for Mac, such as attach, which might be related to modttl.