Heavy Networking 625: Home IoT Networking At Scale

How To Use Grep + Regex To Match Non-200 HTTP Status Codes In Apache Server Logs

When parsing Apache web server logs on Linux, I find it interesting to monitor access requests resulting in HTTP status codes other than 200s. An HTTP status code in the 200s mean the request was successful, and hey–that’s boring.

I want to see the requests that my dear Apache instance is upset about. So the question becomes…how do I filter the logs to show me every entry that doesn’t have a status code in the 200s?

Let’s back our way into this. We’ll start with the answer, then explain how we got there.

The Answer

This CLI incantation will get the job done.

sudo grep -E '\" [1345][01235][0-9] [[:digit:]]{1,8} \"' /var/log/apache2/access.log

If you’d like to watch the log entries scroll by in real time, try this.

sudo tail -f /var/log/apache2/access.log | grep -E '\" [1345][01235][0-9] [[:digit:]]{1,8} \"'

Comprehending The Regex

Let’s focus on the regular expression (regex) grep is using to find the matches. In plain English, the grep utility is using an extended -E regex to display all lines in the file /var/log/apache2/access.log matching the regex.

The regex portion of the command is as follows.

'\" [1345][01235][0-9] [[:digit:]]{1,8} \"'

The regex is enclosed in single quotes Continue reading

Can Fantastical Openings Replace Calendly?

TL;DR

Fantastical Openings can’t replace Calendly for my scheduling needs yet, but it’s close.

The Rest Of The Story

I use Calendly so that folks can schedule me for appointments. I send people a Calendly link, and they choose an available time slot. Calendly creates calendar invitations and sends them to me and the requestor. Calendly also integrates with Zoom, so that an invite comes with a Zoom meeting already attached.

In my years of Calendly use, I’ve found it to be…

• Reliable. It just works.
• Flexible. The availability rules engine allows me to configure conditions such as “leave a gap of X minutes between appointments” that I rely on to keep my calendar sane.
• Expensive. $144/year for the features I need.

I also use Fantastical by Flexibits. In my few months as a Fantastical user, I’ve found it to be…

• Beautiful. It’s the best calendaring interface of anything I’ve tried.
• Integrated. I use Fantastical to integrate with multiple calendars, Zoom, and the Todoist task manager. I use Fantastical both on my Mac and iOS devices.
• A super power. Fantastical happens to be highly compatible with how I work. I am more productive with Fantastical.
• Affordable. $40/year for the features Continue reading

Career Advice I’d Give To 20, 30 and 40-Something Year Old Me

Career Advice To 20-Something Year Old Me

Start that business. You have sufficient technical & business skills, and you can figure out what you don’t know. Take the chance now while you have little at risk.

You’re not the standard everyone else is supposed to live up to. Work on your own faults. They are legion.

Your boss is your boss for a reason. You’re not the boss for a reason, too. When you understand and accept those reasons, you’ll reduce the workplace friction you keep experiencing.

Meritocracy doesn’t mean what you think it means. Being good at your job doesn’t mean you deserve a promotion.

More responsibility comes easy, because no one wants it. More compensation comes hard, because everyone wants it.

Business owners who cheat their partners & customers will cheat their employees, too. Run at the first sign of dishonest business dealings.

Career Advice To 30-Something Year Old Me

Define your goals so you know when you’ve reached them. Otherwise, you’ll exhaust yourself with endless effort.

You are your own worst critic. Take yourself less seriously.

When you work for someone else, you are a replaceable component in a larger machine. This is by design.

You don’t Continue reading

Heavy Networking 623: Growing From Junior To Senior Engineer

Today's Heavy Networking is a roundtable conversation about career growth. Maybe your title is junior engineer, but you want to be a senior engineer. Be careful what you wish for! Maybe your title is junior but you feel you’re doing the job of a senior. Are you really? How would you justify this to your manager? We address these and other questions and issues including certs vs. experience, paying dues, the importance of communication skills, and more.

The post Heavy Networking 623: Growing From Junior To Senior Engineer appeared first on Packet Pushers.

Heavy Networking 623: Growing From Junior To Senior Engineer

Tech Bytes: The Advantages Of Singtel SD-WAN For Cloud Access (Sponsored)

On today's Tech Bytes with sponsor Singtel, we look at SD-WAN as a critical network feature for cloud access, including the use of overlays to simplify operations. We also discuss why organizations might consider a service provider for SD-WAN and dig into Singtel's SD-WAN offering.

The post Tech Bytes: The Advantages Of Singtel SD-WAN For Cloud Access (Sponsored) appeared first on Packet Pushers.

Tech Bytes: The Advantages Of Singtel SD-WAN For Cloud Access (Sponsored)

How To Fix Ubuntu 18.04 ‘apt update’ Throwing An NGINX Repository i386 Package Error

When running ‘apt update’ on Ubuntu 18.04 to prepare for routine system patching, the system kicked back the following error.

N: Skipping acquire of configured file 'nginx/binary-i386/Packages' as repository
'http://nginx.org/packages/ubuntu bionic InRelease' doesn't support architecture 'i386'

The issue is that the existing sources list file for NGINX has gone stale, and appears to be requesting the i386 package. NGINX does not support i386 on Ubuntu 18.04 (Bionic). The solution is to update the sources list file for NGINX.

OLD /etc/apt/sources.list.d/nginx.list

deb http://nginx.org/packages/ubuntu bionic nginx

NEW /etc/apt/sources.list.d/nginx.list

deb [arch=amd64] http://nginx.org/packages/mainline/ubuntu/ bionic nginx

After this change, the error should be gone when running ‘apt update’.

For More Information

NGINX Linux Packages

NGINX update issue (Ubuntu 18.04 Bionic) – Vesta Control Panel Forum

Ubuntu Server 18.04 Nginx i386 – StackOverflow

Heavy Networking 621: Get Scalable Network Automation With Itential (Sponsored)

On today's Heavy Networking, sponsor Itential joins us to discuss how you can deliver a scalable and sustainable network automation system for your enterprise. Our guest is Peter Sprygada, VP of Product Management at Itential.

The post Heavy Networking 621: Get Scalable Network Automation With Itential (Sponsored) appeared first on Packet Pushers.

Heavy Networking 621: Get Scalable Network Automation With Itential (Sponsored)

How To Create A Python Function You Can Call From Other Scripts

Python gives you the ability to write a bit of code and the call that code as a function. You can call the function from within the same script where the function is defined, or you can save the function in a separate script and then import the function inside of other scripts.

Writing and calling functions is a key component of the Don’t Repeat Yourself (DRY) principle of software development. Creating a function in a single script and calling that function from other scripts is preferable to performing copypasta of the same bit of code throughout several scripts. When a function lives in a single script, it only needs to be updated in that one place when it inevitably needs updating.

While Python functions can perform isolated tasks, my typical use cases send values into the function and receive a value returned from the function. In this example, I’ll import a Python function used to refresh an access token required to authenticate to a remote API endpoint. I’ll pass other tokens required to refresh the access token into the function, and the function will return the refreshed access token back to the calling script.

The Function

The names of Continue reading

Heavy Networking 620: High Frequency Trading And Big Data Network Design

Network design for high frequency trading and big data networks is the topic of today’s Heavy Networking. If you’re interested in what it’s like to carefully manage data center latency and maintain your sanity in a zero downtime environment, this is your show. Our guests are are Jeremy Filliben and Marc Washco of Jump Trading.

The post Heavy Networking 620: High Frequency Trading And Big Data Network Design appeared first on Packet Pushers.

Heavy Networking 620: High Frequency Trading And Big Data Network Design

How To Blackhole (Null Route) An IPv6 Block On Linux Using ‘ip -6 route’

If there’s an IPv6 netblock you’d like your host to stop responding to, one tactic is to blackhole the traffic. That is, send any traffic from your host destined to the troublesome IPv6 netblock into a blackhole. Blackholes are also called null routes.

A Simple Example

Let’s say I’m getting repeated SQL injection attacks from various hosts in IPv6 block 2a09:8700:1::/48. Just a totally random example with no basis in reality whatsoever, whoever you are in Belize. There are various ways I can defend against this, but one (sorta ugly) option (I don’t actually recommend, read to the bottom to see my logic) is to create a blackhole aka a null route.

On many flavors of Linux, including Ubuntu 18.04, 20.04, and 22.04, I can accomplish this task with the ip route utility. Let’s take a look at our existing host routing table.

user@host:~$ ip route
default via 123.94.146.1 dev enp1s0 proto dhcp src 123.94.146.227 metric 100
169.254.169.254 via 123.94.146.1 dev enp1s0 proto dhcp src 123.94.146.227 metric 100
123.94.146.0/23 dev enp1s0 proto kernel scope link src 123.94.146. Continue reading

What Does An ‘R’ Before A String Mean In Python?

R Means ‘Raw String’

An ‘r’ before a string tells the Python interpreter to treat backslashes as a literal (raw) character. Normally, Python uses backslashes as escape characters. Prefacing the string definition with ‘r’ is a useful way to define a string where you need the backslash to be an actual backslash and not part of an escape code that means something else in the string.

Examples

1. In this example, Python will interpret each ‘\t’ found in this string as a tab. That is, the backslash+t is interpreted as an escape sequence with a special purpose.

>>> 'path\to\the\thing'
'path\to\the\thing'
>>> print('path\to\the\thing')
path o he hing
>>>

2. By adding the leading r, Python will know that the backslashes are to be interpreted as literal characters and not escape sequences. Interestingly, note how Python represents the literal backslash–as an escape sequence of backslash + backslash.

>>> r'path\to\the\thing'
'path\\to\\the\\thing'
>>> print(r'path\to\the\thing')
path\to\the\thing
>>>

3. This means another way to handle the literal backslash problem is to use backslash + backslash in your string definition. However, this feels like a clunkier way to define the string to me when compared to using ‘r’. Using ‘r’ makes for, I think, more readable Continue reading

Podcast Guest: Can You Have A Successful IT Career Without A Degree?

I was a guest on the February 22, 2022 episode of the So You Wanna Be In IT podcast.

Certifications

I chatted with hosts Pat & Dean about how my career got started. I’ve been around IT since the 90s, so my start was with Novell certification that became Microsoft certification that became Cisco certification. We talk about certs and the job opportunities I took advantage of driven by those certs.

Can You Have A Successful IT Career Without A Degree?

Along the way, we discussed whether or not someone can have a successful IT career without a college degree. Put another way, are IT certifications good enough? I think that yes, you can have a successful IT career without a degree, but that the question, “College degree. Yes or no?” deserves more analysis than a simple yes or no answer offers. Like anything, choosing not to attend university has tradeoffs. We discuss this at some length in the podcast.

What IT Roles Are In Demand In 2022?

The degree vs. certifications part of the discussion transitioned into my takes on IT careers in 2022–especially related to infrastructure. 2022 is an interesting time to be in IT. There are Continue reading

Heavy Networking 618: Building Virtual Networks With Console Connect (Sponsored)

On today’s Heavy Networking episode we talk with sponsor Console Connect, which provides software-defined interconnections for enterprises and service providers. Guests Paul Gampe and Jay Turner dig into the Console Connect catalog, including Internet On-Demand, CloudRouter, and some of the interesting partner integrations that provide unique connectivity options.

The post Heavy Networking 618: Building Virtual Networks With Console Connect (Sponsored) appeared first on Packet Pushers.

Heavy Networking 618: Building Virtual Networks With Console Connect (Sponsored)

How To Pass Environment Variables To A Remote SSH Deployment With PyCharm

I pass access tokens, authentication keys, and other secrets to Python scripts via environment variables rather than encode these values into the scripts themselves. If I was a real boy, I’d use a solution like Hashicorp Vault or other secrets management tool (there’s a bunch of them), but I haven’t yet found the motivation to learn such a tool.

I’m not sure I’d want to build and maintain such a tool if I did find the motivation. I’m sort of lazy sometimes is what I’m saying. So for now, environment variables it is.

PyCharm allows for the passing of environment variables from the IDE to a script, whether that script is running locally or in a remote SSH deployment you’ve configured for your project.

To set the environment variables, select Edit Configurations from the Run menu.

Or in the project bar above the code window, click the dropdown with your script name, and select Edit Configurations.

Either way brings up the following configuration window for the scripts in your project. In the Environment variables: field, click the icon.

That will bring up the following window you can use to configure the environment variables.

Fantastic. But how do we assign the Continue reading