Error listening on port 80

[TravelingTechGuy]

1. Started htracr 80 -> got "Server running on port 80".
2. Browsed to localhost
3. Clicked start -> got "Sniffing on en0"
4. Browsed to another page -> got:

/opt/local/lib/node_modules/htracr/htracr.js:276
    if (packet.link.ip.tcp.dport == 80) {
                      ^
TypeError: Cannot read property 'tcp' of undefined
    at Object.htracr.save_packet (/opt/local/lib/node_modules/htracr/htracr.js:276:23)
    at Pcap.<anonymous> (/opt/local/lib/node_modules/htracr/htracr.js:93:12)
    at Pcap.emit (events.js:95:17)
    at packet_ready (/opt/local/lib/node_modules/htracr/node_modules/pcap/pcap.js:42:12)
    at SocketWatcher.pcap_read_callback [as callback] (/opt/local/lib/node_modules/htracr/node_modules/pcap/pcap.js:62:43)

[mnot]

• What user are you running as?
• What versions of nodejs / pcap, etc?
• Is anything else listening to 80?

[TravelingTechGuy]

• Admin user (sudo ...)
• Node 0.10.32, NPM 2.1.2, pcap - not sure, how do I find out?
• No. At least not on the machine itself. I am in a corporate environment though, so who knows.

I did verify it's not a collision, by actually changing the port to one that my current node app is using. It quits with a proper error.