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Testing if a port can be reached, using built-in tools other than 'good old telnet'

Have you ever wanted to test (from the command line) whether a port on another machine can be reached from yours? When some app of your can't seem to connect to a given port, you may want to test things from the command line. (The problem may be that the service using that port has stopped or is blocked by a firewall--it may be that you're mistaken in the port you are trying to use, or perhaps even the ip address, domain name, or machine name.)

There are in fact many tools which can help with this task, some of which will be familiar to those on *nix systems, but Windows users who've been around a while (or who learned from such folks) may try to rely on the good ol' telnet command (as in telnet [machine] [port]). Unfortunately, they often find out how Microsoft has disabled that tool by default for over a decade (since Windows Vista), and while it can be easily enabled, they may be prevented or understandably reluctant to do that.

In this post, I want to show a couple of command-line alternatives which can do the job easily, one best suited for powershell users (Test-NetConnection), and and two of which would suit those who prefer the command line (cmd) and which are now built-into Windows (the past few years): ssh and curl. No, this is not their primary job but they will suit for this task and it may surprise some to learn they're even built-in options. I'll conclude with still other options available to those on *nix environments (who of course can also use ssh and curl), especially nc (netcat).

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Come see my online talk, "Migrating or Comparing CF Admin Settings", at noon ET on Aug 13

Note: This blog post is from 2020. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
Just thought I'd share a heads-up here on the blog that I'll be the speaker for the Online ColdFusion Meetup this week, Aug 13, at noon ET, presenting a new talk:

Migrating or Comparing CF Admin Settings, between instances, versions, and engines

You can learn more (including the description, the online meeting URL, where the recording will be posted, and more) at the meetup event page. FWIW, the session name had to be shortened a bit as presented on the meetup site there and even in the title here. :-)

As a bonus for you, my blog readers, I'll note that I'll be covering the CF migration and CAR features, the Commandbox CFConfig tool (which can be used for more than just "box" instances) and the CF2020 cfsetup tool (which has been shown publicly already), and more.

I'll also have a special surprise for people who "just want to compare the Admin settings of two instances without resorting to command-line tools, or hopping back and forth between browser tabs", using a free cross-platform GUI compare tool (and a simple trick in the CF Admin) which has delighted nearly everyone I've ever shown it to. And the tool can benefit you for far more than this one task. :-)

Configuring FusionReactor to show "real ip address" when behind a load balancer or other proxy

Note: This blog post is from 2019. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
If your server is behind a load balancer or other sort of proxy, you may have noticed that when you view information about requests in FusionReactor, they all have the same (or nearly the same) IP address. This can be easily fixed, and I show you how in this post.

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VisualVM failing to find plugins/updates? Solving the 503 error with an updated URL

Note: This blog post is from 2017. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
Have you tried to update or simply see the available plugins for VisualVM (the Java monitoring tool built into the JDK), and found that it fails to respond right away (the progress bar will show "checking") and then it reports:

Unable to connect to the Java VisualVM Plugins Center because of Server returned HTTP response code: 503 for URL: http://www.oracle.com/splash/java.net/maintenance/index.html

There is a solution.

TLDR: the quick answer is to change the URL used by the tool (Tools>Plugins>Settings) to use a new URL, such as https://visualvm.github.io/uc/8u131/updates.xml.gz.


For those who'd appreciate more detail, read on.

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Four free tools I (nearly) always install on a new machine and use everyday

Note: This blog post is from 2014. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
I'd like to recommend four free tools that I think everyone (running Windows) should consider installing on their machines, as they can help with day to day tasks that many (certainly I) hit every day.

They don't run in the background, only doing their job when you ask them to, so I find them safe to install and use on production servers, though of course any tool can be abused. I've never seen these to cause a problem in many thousands of uses.

I was reminded to share this list today as I was helping a customer, as I got on their server with them to help them solve a problem. I recommended we install these as I do on nearly all my engagements (and indeed on all my own machines). I think they really are fundamental tools, as I'll explain below.

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Tracking ColdFusion sessions within FusionReactor, by way of FREC logging

Note: This blog post is from 2013. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
Someone asked on the FusionReactor mailing list (a Google Group) whether FusionReactor tracked CF sessions. I started to write a reply, with the good news/bad news in answer to that, and as sometimes happens, it became long enough that I thought it might be better suited as a blog entry that I could point to from the list instead, and which may also help those not on the list (which is a great resource, as a low-volume list with a high signal to noise ratio.)

Anyway, here is the answer I wanted to offer to that question...

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How to tell what, if any, hotfixes have been applied to ColdFusion (9 and earlier)

Note: This blog post is from 2012. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
I often see people struggling with confusion over what hotfixes have been applied to CF. They may wonder "which have we applied?", or worse, they may not have applied any and just don't know "how to know" whether they have. I have good news, but it may not be the answer most would suspect.

The common answer offered is that one should use the "system info" page in the CF Admin, and its available "update level" field.

But I will assert that's not the "right answer" after all, or certainly not the "best answer" to really know what hotfixes (plural) have been applied. Know why? If not, I'll explain here, and I'll show what I would say is the "right" answer to "what hotfixes have you applied?"

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Need to solve browser problems? Did you know most modern browsers now have built-in developer tools?

Note: This blog post is from 2012. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
When you're trying to understand why something's not working in your browser (page not rendering as expected, feature not working as expected, page content failing to load), it's useful to use of many any available tools which can show you what's going on, whether with respect to the HTML, CSS, or Javascript that may be running, or perhaps the communications between the browser and server.

For years, experienced developers have recommended client-side proxy tools like Firebug, Fiddler, Charles, and such. I list these and many others as a category in my CF411 site listing over 1800 tools and resources for CFers, in the category, HTTP Debugging Proxies/Sniffers/Web Client Test Tool.

I recently updated the list, though, to point out these "built-in" forms of these tools, now available in most browsers. If you may be in a place where you are "not allowed" to install new software (or are simply disinclined), knowing that the browser may have such a valuable tool built-in can be a real discovery, thus this entry.

Here's the content that I've added to that section:

  • In Chrome, see the Dev Tools, available under the "Customize and control Google Chrome" icon at the top right (the monkey wrench), then Tools>Developer Tools.
  • In Firefox 6 and above, see the "Web Console" feature in the "Web Developer" tools, available under the Tools menu.
  • In Internet Explorer, see the Developer Toolbar which is an ad-on for IE 6 and 7, and the f12 Developer Tools that are built into IE 8 and 9 (in the Tools menu).
  • In Opera, see the Developer Tools in Opera DragonFly, available in the Edit>Developer Tools menu in Windows, and Tools>Advanced on Mac.
  • In Safari, see the "Web Inspector" feature of the Develop menu.
  • I welcome additions/corrections/feedback.

The links I've given for each of these often have friendly introductions to using such tools. I can also commend an old but classic discussion of such tools, here.

Have you used these sort of tools? How have they helped you. Are you surprised to learn that the browsers now have such tools built-in? Chime in and share your thoughts. I may do a later blog entry or talk introducing using these tools for some common problems working with CF.

Need to look at large files? Consider free Universal Viewer

Note: This blog post is from 2010. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
If you have any reason to look at large files (especially log files) on Windows, don't use NotePad (it doesn't like large files)! Sure, you can perhaps use WordPad, or you may be using a favored editor like TextPad, UltraEdit, NotePad++, and so on. But those are editors: they generally presume you want to change the file.

If you just want to look at a file, there's a great free tool to do it: UniversalViewer.

It can open a 1GB file as fast as a 1kb file (because it only pulls in what it needs to show the screen full of text you're looking at.) And there are times when you may well need to look at some very large files, especially when troubleshooting CF servers, like I do.

And actually, as its name implies, UniversalViwer can view far more than just text files, including images and more.

I've just only ever used it for looking at log files, for which it excels (and yes, you can search within the file, set it to tail files, and more.)

I've been touting the tool for years in classes and presentations, and I was about to mention it in another blog entry, but then I realized I'd not blogged about it on its own. Rather than have the reference lost in another blog entry, here's its moment to shine!

And yes, I do realize there are several other tools that can do this. I list this one and several others in a category of my CF411 list: Generic File View/Log Analysis Tools. (Note that there are some nifty tools in that category there for looking specifically at CSV files, as well as other entire categories for specific kinds of logs, like CF logs, web server logs, windows event logs, etc.)

Still suffering from spam/junk email? If using Outlook or Thunderbird, consider CloudMark

Note: This blog post is from 2010. Some content may be outdated--though not necessarily. Same with links and subsequent comments from myself or others. Corrections are welcome, in the comments. And I may revise the content as necessary.
Are you still suffering from spam or junk mail in your email inbox? If you're using Outlook or Thunderbird, you should consider CloudMark, a service I've used for years. I'd like to share a bit about it, for those who may benefit.

Before proceeding though, let me say that I realize there are many spam solutions, including ones based on your mail server instead (that you or your host might implement).

And yes, of course I do realize that folks using Gmail will want to say that they never have to worry about this at all!

Let me please just speak to those who do choose to (or have to) receive email from other mail servers, and perhaps can't control spam handling on the server, or still favor a client solution.

Background

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