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Regex Collection

May 14, 2015 – 12:29 pm |

Just a small collection of POSIX regular expressions that may come in handy for writing sysadmin scripts.

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Networking

Unix and Linux network configuration. Multiple network interfaces. Bridged NICs. High-availability network configurations.

Applications

Reviews of latest Unix and Linux software. Helpful tips for application support admins. Automating application support.

Data

Disk partitioning, filesystems, directories, and files. Volume management, logical volumes, HA filesystems. Backups and disaster recovery.

Monitoring

Distributed server monitoring. Server performance and capacity planning. Monitoring applications, network status and user activity.

Commands & Shells

Cool Unix shell commands and options. Command-line tools and application. Things every Unix sysadmin needs to know.

Commands & Shells, Networking »

Detecting Synology NAS with nmap

May 29, 2015 – 3:07 pm |

Just a quick note for myself on how to find Synology NAS servers on the network without having to use the bulky Windows utility that ships with these systems. Read the full story »

Dealing With Prolific Emailers

May 26, 2015 – 2:39 pm |

So you come back from vacation, open Outlook and see thousands of unread emails. Who sends all this stuff? There’s an easy way to identify the sources of this background noise. In Outlook’s inbox, select …

BASH History Control

May 12, 2015 – 12:01 pm |

The standard output of the “history” command will show you the last one thousand commands executed by the user. This is useful, of course, but there are a few issues. Sometimes it’s important to know …

Verify Email SSL Certificate from CLI

May 8, 2015 – 10:36 am |

Just a quick reference for validating SSL certs on mail servers. This is not something I have to do often, but when the need arises, I find myself googling the answer every single time. So …

Extending Swap on LVM2 Logical Volume

May 7, 2015 – 11:16 am |

To grow swap on LVM you will need to temporarily disable the swap LV. This will leave without swap space, which may upset some applications (Oracle). So the first step should be to set up …

Faking the Uptime in Linux

May 4, 2015 – 10:05 pm |

If, for whatever reason, you need to fake the Linux server uptime, there is a hacked kernel module you can use. The instructions are below.

Resetting HP ILO from OS

May 4, 2015 – 11:02 am |

You can use ipmitool package in Linux to reset your HP server’s ILO password. The basic instructions are below.

Removing CTRL-M from Unix Files

April 16, 2015 – 4:44 pm |

This is a simple but annoying and persistent problem: text files edited on Windows and the uploaded to Unix acquire the “^M” character at the end of each line. In my experience, this little problem …

Observium Agent Installation on Pidora

April 13, 2015 – 11:50 am |

Just some quick notes on installing Observium agent on Raspberry Pi running Pidora. Pretty much the same process applies to any Fedora-like flavor.

Log Event Time Distribution

April 2, 2015 – 11:04 am |

When “once in a while” answer is insufficient and you need to know exactly how often a particular event occurs on the system, there are a few easy things you can try from command line.

Late Night Rant #26

March 30, 2015 – 12:30 am |

When you’ve ls’d, grepped, catted, piped and tailed everything on your computer and there is absolutely nothing left to do, there’s always this…

Login Monitor

March 6, 2015 – 12:02 am |

Sometimes after a couple of beers I start feeling paranoid. I make sure the door is locked and check my firewall logs. Here’s a very basic script to monitor your server’s login record and notify you about …

Installing Salt Minion on RHEL5

February 19, 2015 – 10:38 am |

As of recently, python26-distribute has been removed from EPEL5 due to lack of support and attempting to install salt-minion on RHEL5 will throw a dependency error. If you are still running RHEL5, you would need …

Late Night Rant #25b

February 17, 2015 – 5:41 pm |

No sooner than I stopped complaining about HP’s “holy” Web site, I ran into a similar issue with Red Hat’s site. And that doesn’t happen very often. Unlike HP, Red Hat folks tend to take better …

Late Night Rant #25: HP’s Web Site Fail

February 12, 2015 – 6:24 pm | One Comment

I’ve already mentioned my dislike for the epic mess of broken links HP gingerly called its Web site. Nearly a year-and-a-half later the situation did not improve. Actually, it might have gotten worse.

Memory Utilization-by-User

February 10, 2015 – 5:13 pm |

Here’s a useful one-liner (sort of) that will show you memory utilization details by user ID on Linux (RHEL, Fedora, CentOS) systems. This may come in handy when trying to figure out who is eating …

Late Night Rant #24: North Korean Internet

December 22, 2014 – 8:05 pm |

Today was the day the North Koreans would have learned they had the Internet and the Americans DDOSed it. Unfortunately, they had no Internet, poor bastards. But, as long as this keeps us entertained… Hey, …

Late Night Rant #23: Kim The Sony-Slayer

December 17, 2014 – 10:09 pm |

Sony execs are shedding crocodile tears over the latest IT security breach that brought substantial financial losses to the company. Let’s not dwell on the trivial: who did it and why are irrelevant technicalities. How …

RHEL/CentOS Yum Operations

December 14, 2014 – 11:42 pm |

The Yellowdog Updater, Modified has more features than most of us will ever need. Below are some hopefully useful examples that will help keep your system maybe secure by replacing old known bugs with new …

Using Pflogsumm Postfix Log Analyzer

December 4, 2014 – 12:29 am |

Pflogsumm is an oldie but a goodie. It’s a Perl script that sifts through your Postfix server maillog and provides you with a neat summary of events and some statistics. This information can be useful …

Visualizing Apache Logs with Logstalgia

December 4, 2014 – 12:01 am |

The Logstalgia is a cool graphical utility for visualizing the Apache access_log files. The practical value of Logstalgia is debatable, but it’s entertainment value is not in question. The managers and NOC operators can stare …

Sending Attachments Using Mailx

December 3, 2014 – 2:32 pm |

Sometimes it’s just better to attach a file to your email than to “cat” the contents into the email body. You will need the “uuencode” utility installed. On CentOS/RHEL you can install it by doing …

Fail2ban Whitelist IPs

December 2, 2014 – 9:16 pm |

Fail2ban is an excellent security tool that will do a good job safeguarding your server. However, using fail2ban you may run into two issues: friendly fire and inability to permanently ban hostile networks. I already …