A while back, I wrote about the critical roles CLIs (command-line interfaces) play in just about every facet of the IT infrastructure. I got plenty of nods in agreement via email and in the comments, but I still receive emails claiming that I'm trying to drag computing back to the "dark ages of the C:\ prompt," and there's usually a whole lot of "you want to turn IT back into an Ivory Tower."
I fear I've been misunderstood by some, no matter how well understood by others. I'm going to take a few minutes and give everyone a very concrete example. Forgive me for belaboring the obvious.
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Say there are two companies, precisely the same size and in the same industry. On one side, we have an admin who's using a Cisco ASA (though the make and model could differ), and the other is using an XYZ firewall with only a Web-based GUI interface. Yes, the ASA probably cost a bit more, but it's based on a very mature CLI. The XYZ firewall has no CLI at all. We'll call them CLI Inc. and GUI Industries.
Both companies are fortunate in that a new carrier has come to town and wants to light up their location with fiber. They can finally ditch those expensive T3 circuits, which will represent a massive cost savings, while increasing bandwidth more than 100 percent. Everyone is thrilled -- except the firewall admin with the GUI.
You see, both companies have a significant external presence, are using most of a full class C externally, and will be renumbering to connect to the new service. This means that the translation tables on each company's firewall must change completely. Mind you, we're talking about more than 200 IP addresses. Oh, external DNS will have to change too. Since both companies run their own external DNS servers, they'll have to modify those records to coincide with the cutover.
Naturally, GUI Industries is using Windows as its external DNS server. Meanwhile, CLI Inc. is using a Linux box running BIND9.
The network and DNS admins at both companies get their new subnet assignments and begin mapping the translations. Using a spreadsheet, they have one column with the service name and two columns containing the old and new IP addresses. They're pretty much a 1-to-1 matchup, but they take the opportunity to remove some old addresses that aren't in use any more and move a few services around. They plan carefully and make sure they've covered all their bases, as the cutover date is only a week away so that they can terminate their T3 contracts without getting hit with a wasted month of service.