While searching for a method to update 'tcpdump' (packet sniffer) in Sierra I came across a PPC GUI front end to 'tcpdump' called MacSniffer. Having retired my PPC systems I'm not able to test this program, but will gladly update this post (to make it easier for future viewers) with feedback. Here is a description of MacSniffer: MacSniffer is a front end to the built-in 'tcpdump' packet sniffer on Mac OS X. MacSniffer allows you to view all of the traffic on a network connection, such as ethernet. MacSniffer includes a filter editing interface and a filter library to easily construct and reuse packet filters to view a subset of all the traffic on the connection, such as just that destined for a specific host or port. You can choose the level of detail you want captured, from just the minimal packet headers (showing source and destination hosts and ports) up to a full hex and ASCII dump of the packet contents. MacSniffer can be useful for diagnosing many network problems, debugging client/server programs, and scanning for particular network exploits in real time. The original publisher is gone, but it can still be downloaded via the Internet Wayback machine at this URL: https://web.archive.org/web/20110628222003/http://personalpages.tds.net/~brian_hill/downloads.html The man page for tcpdump is available here: http://ss64.com/osx/tcpdump.html NOTE: See post #9 from @Lastic RE: needed permission changes.