I was setting up a new PBX for my client and I came to a rather unusual problem. The client was using SIP trunk from Slovak Telecom together with a fresh installation of FreePBX (Linux distro based on CentOS with bundled Asterisk and other candy).
Today, I’m going to tell you about one problem, which brought me sleepless night and could be solved with a few lines of code, as usual.
Internet is a dangerous place. And more often also very controversial, just like the following article. Today I’m going to describe a little bit controversial way how to protect our network against malicious websites by changing replies to DNS requests to these sites.
In previous article of this miniseries we showed how to dramatically speed up Nagios by putting the spool directory into RAMdisk. Today we are going to look at speeding up the very basic check of every host. Like the previous improvement, this came up from real need to eliminate false-positives …
If I read manual, I would save a lot of time and trouble. EdgeCore ES3528_52M switches have ability to schedule reboot in exact date and time (assuming you have correctly synchronized time via NTP). Strongly useful for software upgrades.
In our network we have deployed dozens of EdgeCore ES3528M/ES3552M switches. However, after frequent upgrades and configuration changes, often happens that old config files, opcodes, boot-roms will remain int the flash memory and are no longer needed. Fortunately, since opcode version 1.4.4.0 there is command available which deletes all inactive …
Some RouterBOARD devices (those with “P” in the model name) have the ability to power devices through Power-over-Ethernet (PoE for short). It is a very useful thing, especially after the PoE firmware upgrade to the latest version (currently 2.1), which increases the current limit for the device and port, adds …
Yesterday, I discovered one interesting thing. It’s kind a new for me, but nothing special. There is a useful tool for setting system tunables according to the specific use of machine in RHEL based Linux distros like CentOS etc.
DHCP alerting is a feature of RouterOS, which can alert us on rogue DHCP server on the network. The working principle is easy. Router sends DHCPDISCOVER packet on interface and if there’s reply by router not in whitelist, the incident is logged. This script may become handy during mass deployment …
If we are taking the networking seriously, we have to monitor its status and health of its services. In small networks with number of devices in tens is the whole issue quite simple and the default configuration is sufficient. But what if the network has “grown a little bit” to …