I think it's a good contribution. Couple of things though: - lsof can also print the list of files open by a process. fuser can tell you which process open a s

I think it's a good contribution. Couple of things though: - lsof can also print the list of files open by a process. fuser can tell you which process open a specific file. lsof is mentioned later in the zine though. - sysdig is not mentioned but is great. - wireshark/tcpdump/ngrep/etc might be challenging to practically use in the presence of SSL/TLS. you can mitigate this problem by setting up SSL termination at your network perimeter so you can monitor unencrypted traffic. - additionally to netcat you have curl, httpie and many other clients for similar purposes. in the Chrome developer tools network tab, you can select a request sent when visiting a website and click "Copy as cURL". this will quickly export any request you were making as a cURL command. likewise, proxies like burp also implement this same feature. sometimes you need to debug DNS problems, that is not covered sadly. I use dig for this purposes but I wonder if there's something better. if you are going to be using command line utilities, getting acquainted with cat, grep, cut, sed, awk, tail, head, colrm, tr, sort, uniq, comm, wc, etc. is very recommended. ministat is also cool. then, about java and node... java has excellent profiling tools, including the free jvisualvm tool shipped with Java that does the job for the most part. profiling and debugging node in runtime can be really challenging. specially analyzing node coredumps with mdb_v8 is not for the faint of heart... you need to set up a VM with joyent's SmartOS for this. there's an npm package that simplifies this process called "autopsy". now, flamegraphs might be fine, but i strongly prefer nodegrind + qcachegrind.