Sandra Henry-Stocker, Author at NetworkingNexus.net

Sandra Henry-Stocker

Author Archives: Sandra Henry-Stocker

22 essential security commands for Linux

There are many aspects to security on Linux systems – from setting up accounts to ensuring that legitimate users have no more privilege than they need to do their jobs. This is look at some of the most essential security commands for day-to-day work on Linux systems.sudo Running privileged commands with sudo – instead of switching user to root – is one essential good practice as it helps to ensure that you only use root privilege when needed and limits the impact of mistakes. Your access to the sudo command depends on settings in the /etc/sudoers and /etc/group files. [ Two-Minute Linux Tips: Learn how to master a host of Linux commands in these 2-minute video tutorials ] $ sudo adduser shark Adding user `shark' ... Adding new group `shark' (1007) ... Adding new user `shark' (1007) with group `shark' ... Creating home directory `/home/shark' ... Copying files from `/etc/skel' ... Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully Changing the user information for shark Enter the new value, or press ENTER for the default Full Name []: shark Room Number []: Work Phone []: Home Phone []: Other []: Is the information correct? [Y/n] Y If you run sudo Continue reading

22 essential Linux security commands

How to speak Linux

I didn’t even stop to imagine that people pronounced Linux commands differently until many years ago when I heard a coworker use the word “vie” (as in "The teams will vie for the title") for what I’d always pronounced “vee I”. It was a moment that I’ll never forget. Our homogenous and somewhat rebellious community of Unix/Linux advocates seemed to have descended into dialects – not just preferences for Solaris or Red Hat or Debian or some other variant (fewer back in those days than we have today), but different ways of referring to the commands we knew and used every day.The "problem" has a number of causes. For one thing, our beloved man pages don't include pronunciation guidelines like dictionaries do. For another, Unix commands evolved with a number of different pronunciation rules. The names of some commands (like "cat") were derived from words (like "concatenate") and were pronounced as if they were words too (some actually are). Others derived from phrases like "cpio" which pull together the idea of copying (cp) and I/O. Others are simply abbreviations like "cd" for "change directory". And then we have tools like "awk" that go in an entirely different direction by Continue reading

Blacklisting modules on Linux

The Linux kernel is modular — composed of modules that work together but are largely independent of each other. New functionality can be added when a kernel module is loaded, but there are times when you might need to block functionality because modules interfere with each other or leave a system vulnerable. When that is the case, you can restrict what modules the kernel is able to use by blacklisting the troublemakers. This blocks them from being loaded.Listing Kernel modules You can list kernel modules with the lsmod command. For a taste of what you’re likely to see, the lsmod command below shows us the top of the lsmod command output on a sample system.To read this article in full, please click here

Customizing your text colors on the Linux command line

If you spend much time on the Linux command line (and you probably wouldn't be reading this if you didn't), you've undoubtedly noticed that the ls command displays your files in a number of different colors. You've probably also come to recognize some of the distinctions — directories appearing in one color, executable files in another, etc.How that all happens and what options are available for you to change the color assignments might not be so obvious.[ Also read: Unix tip: Coloring your world with LS_COLORS | Get regularly scheduled insights by signing up for Network World newsletters. ] One way to get a big dose of data showing how these colors are assigned is to run the dircolors command. It will show you something like this:To read this article in full, please click here

What’s behind Cisco’s comeback?

Cisco Systems Inc. (NASDAQ: CSCO) in just the last week or so has taken over the top spot for year-to-date performance among the 30 equities comprising the Dow Jones industrial average, with its shares having risen nearly 20 percent in 2018. That’s a big deal. How did it happen? What pushed Cisco beyond its best-known-router reputation to being a top performer on the DOW?A little history Cisco has been around for nearly as long as I've been working on Unix and Linux systems. Founded in December 1984 by two Stanford University computer scientists and clearly named after San Francisco, its logo clearly depicts the two towers of the Golden Gate Bridge and its line of products have kept it a major player in routers and switches. In fact, Cisco was on top of the tech world before the dot.com meltdown. Then it plunged with the rest of the tech sector.To read this article in full, please click here

What’s behind Cisco’s comeback?

Cisco Systems Inc. (NASDAQ: CSCO) in just the last week or so has taken over the top spot for year-to-date performance among the 30 equities comprising the Dow Jones industrial average, with its shares having risen nearly 20 percent in 2018. That’s a big deal. How did it happen? What pushed Cisco beyond its best-known-router reputation to being a top performer on the DOW?A little history about Cisco Cisco has been around for nearly as long as I've been working on Unix and Linux systems. Founded in December 1984 by two Stanford University computer scientists and clearly named after San Francisco, its logo clearly depicts the two towers of the Golden Gate Bridge and its line of products have kept it a major player in routers and switches. In fact, Cisco was on top of the tech world before the dot.com meltdown. Then it plunged with the rest of the tech sector.To read this article in full, please click here

How to share files between Linux and Windows

Many people today work on mixed networks, with both Linux and Windows systems playing important roles. Sharing files between the two can be critical at times and is surprisingly easy with the right tools. With fairly little effort, you can copy files from Windows to Linux or Linux to Windows. In this post, we'll look at what is needed to configure your Linux and Windows system to allow you to easily move files from one OS to the other.Copying files between Linux and Windows The first step toward moving files between Windows and Linux is to download and install a tool such as PuTTY's pscp. You can get PuTTY from putty.org and set it up on your Windows system easily. PuTTY comes with a terminal emulator (putty) as well as tools like pscp for securely copying files between Linux and Windows systems. When you go to the PuTTY site, you can elect to install all of the tools or pick just the ones you want to use by choosing either the installer or the individual .exe files.To read this article in full, please click here

How to do math on the Linux command line

Can you do math on the Linux command line? You sure can! In fact, there are quite a few commands that can make the process easy and some you might even find interesting. Let's look at some very useful commands and syntax for command line math.expr First and probably the most obvious and commonly used command for performing mathematical calculations on the command line is the expr (expression) command. It can manage addition, subtraction, division, and multiplication. It can also be used to compare numbers. Here are some examples:Incrementing a variable $ count=0 $ count=`expr $count + 1` $ echo $count 1 Performing a simple calculations $ expr 11 + 123 134 $ expr 134 / 11 12 $ expr 134 - 11 123 $ expr 11 * 123 expr: syntax error <== oops! $ expr 11 \* 123 1353 $ expr 20 % 3 2 Notice that you have to use a \ character in front of * to avoid the syntax error. The % operator is for modulo calculations.To read this article in full, please click here

Finding what you’re looking for on Linux

It isn’t hard to find what you’re looking for on a Linux system — a file or a command — but there are a lot of ways to go looking.7 commands to find Linux files find The most obvious is undoubtedly the find command, and find has become easier to use than it was years ago. It used to require a starting location for your search, but these days, you can also use find with just a file name or regular expression if you’re willing to confine your search to the local directory.$ find e* empty examples.desktop In this way, it works much like the ls command and isn't doing much of a search.To read this article in full, please click here

Fedora 28 Beta is ready for you to test

Fedora 28 has just been released in its Beta version. That means that it isn’t likely to be completely free of bugs and that you have a chance to participate in ensuring that it’s ready to go public on May 1st.This news won’t be particularly surprising to the more enthusiastic Fedora users. Fedora’s release cycle is a fairly regular after all. Every 6 months, more or less, a new Fedora release is published. Many Fedora users have come to expect to see them around May Day and Halloween each year. Yet, while not surprising, the news is still exciting because of a number of new and enhanced features.So, what do you have to look forward to in this Beta release or the planned May release?To read this article in full, please click here

Fedora 28 beta is ready for you to test

Fedora 28 has just been released in its beta version. That means it isn’t likely to be completely free of bugs and that you have a chance to participate in ensuring that it’s ready to go public on May 1.This news won’t be particularly surprising to the more enthusiastic Fedora users. Fedora’s release cycle is a fairly regular after all. Every six months, more or less, a new Fedora release is published. Many Fedora users have come to expect to see them around May Day and Halloween each year. Yet, while not surprising, the news is still exciting because of a number of new and enhanced features.Also read: Review: Free Linux Fedora server offers upgrades as they become available – no wait | Sign up: Subscribe to receive daily Network World updates New features in Fedora 28 beta So, what do you have to look forward to in this beta release or the planned May release?To read this article in full, please click here

Simplifying Linux with … fish?

No, the title for this post is not a mistake. I’m not referring to the gill-bearing aquatic craniate animals that lack limbs with digits or the shark-shaped magnetic Linux emblem that you might have stuck to your car. The “fish” that I’m referring to is a Linux shell and one that’s been around since 2005. Even so, it’s a shell that a lot of Linux users may not be familiar with.The primary reason is that fish isn't generally installed by default. In fact, on some distributions, the repository that provides it is one your system probably doesn't access. If you type "which fish" and your system responds simply with another prompt, you might be missing out on an interesting alternative shell. And, if your apt-get or yum command can't find what you're looking for, you will probably have to use commands like those shown below to get fish loaded onto your system.To read this article in full, please click here

Working with calendars on Linux

Linux systems can provide more help with your schedule than just reminding you what day today is. You have a lot of options for displaying calendars — some that are likely to prove helpful and others that just might boggle your mind.date To begin, you probably know that you can show the current date with the date command.$ date Mon Mar 26 08:01:41 EDT 2018 cal and ncal You can show the entire month with the cal command. With no arguments, cal displays the current month and, by default, highlights the current day by reversing the foreground and background colors.$ cal March 2018 Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Also read: 5 top Linux server distros for enterprises | Sign up: Receive daily Network World updates If you want to display the current month in a “sideways” format, you can use the ncal command.To read this article in full, please click here

Reviewing logins on Linux

The last command provides an easy way to review recent logins on a Linux system. It also has some useful options –- such as looking for logins for one particular user or looking for logins in an older wtmp file.The last command with no arguments will easily show you all recent logins. It pulls the information from the current wtmp (/var/log/wtmp) file and shows the logins in reverse sequential order (newest first).$ last shs pts/1 192.168.0.15 Mon Mar 19 17:48 still logged in shs tty2 /dev/tty2 Mon Mar 19 17:37 still logged in shs pts/2 192.168.0.15 Mon Mar 19 17:22 - 17:23 (00:00) jdoe pts/3 192.168.0.15 Mon Mar 19 16:51 - 17:22 (00:31) To look for logins for just one particular user, supply their username as an argument.To read this article in full, please click here

A new telepresence robot takes the stage

AvaⓇ Robotics, a startup with strong technical ties to iRobot, has just announced its telepresence robot. Her name is Ava and she’s likely to win a lot of hearts. For one thing, Ava is quite perceptive, using video technology from Cisco and integrating with Cisco Spark (which provides tools for team messaging, online meetings, and white boarding). Ava is also quite friendly. She allows her users to participate in remote meetings, wander down hallways at other facilities while chatting with colleagues, and enjoy face to face discussions with people who may physically be thousands of miles away.Telepresence robots provide a lot of benefits to companies that are spread across many locations – especially those spanning continents -- or with staff who work from home. They make work relationships considerably more productive -- even for individuals who may have never met in person. Carrying on casual conversations and checking remote data centers and manufacturing facilities (sometimes safer than being there in person) can make huge differences in how staffs coordinate and get important work done.To read this article in full, please click here

A new telepresence robot takes the stage

Ava Robotics, a startup with strong technical ties to iRobot, just announced its telepresence robot. Her name is Ava, and she’s likely to win a lot of hearts.For one thing, Ava is quite perceptive, using video technology from Cisco and integrating with Cisco Spark (which provides tools for team messaging, online meetings, and white boarding). Ava is also quite friendly. She allows her users to participate in remote meetings, wander down hallways at other facilities while chatting with colleagues, and enjoy face-to-face discussions with people who may physically be thousands of miles away.Also read: Customer reviews: Top Remote Access Tools Telepresence robots provide a lot of benefits to companies that are spread across many locations — especially those spanning continents — or with staff who work from home. They make work relationships considerably more productive — even for individuals who may have never met in person. Carrying on casual conversations and checking remote data centers and manufacturing facilities (sometimes safer than being there in person) can make huge differences in how staffs coordinate and get important work done.To read this article in full, please click here

How to check your network connections on Linux

The ip command has a lot to tell you about the configuration and state of your network connections, but what do all those words and numbers mean? Let’s take a deep dive in and see what all the displayed values are trying to tell you.When you use the ip a (or ip addr) command to get information on all the network interfaces on your system, you're going to see something like this:$ ip a 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: enp0s25: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 00:1e:4f:c8:43:fc brd ff:ff:ff:ff:ff:ff inet 192.168.0.24/24 brd 192.168.0.255 scope global dynamic enp0s25 valid_lft 57295sec preferred_lft 57295sec inet6 fe80::2c8e:1de0:a862:14fd/64 scope link valid_lft forever preferred_lft forever The two interfaces on this system — the loopback (lo) and network (enp0s25) — are displayed along with a lot of stats. The "lo" interface is clearly the loopback. We can see the loopback IPv4 address (127.0.0.1) and the loopback Continue reading

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