Technology Insights

List All IP Addresses Making Port 80 Connections To Linux Server

Earlier while analyzing a Linux server it was pointed out to me that the Apache logs were filling up with constant connections requesting domains that were not configured on the server. To me it looked as if a load balancer somewhere was misconfigured and sending traffic to our IP address by mistake but I needed to open a ticket with the colocation provider to have them look into the issue further since the network in this case is not something I have any control over. Below is a quick Linux command that will output a list of IP addresses making port 80 connections to your server.

Technology Insights

CentOS Linux: sort: invalid option — R, Try sort –help for more information

I was working on an article a couple days ago with a friend and he had sent over some commands for me to reference in the article which included the “sort -R” command. The sort -R switch will randomly sort the contents of a file which is very useful in certain situations. The problem is that the sort command which is installed by the coreutils RPM package on CentOS does not include the -R switch because it is to old. Below I describe the issue in more detail and provide references on how you could upgrade sort on CentOS Linux.

Technology Insights

Install Or Upgrade One Application From coreutils Package On CentOS Linux

Yesterday I needed to upgrade a single application on CentOS Linux. First I figured out that the application was part of the coreutils RPM package which is currently only available up to version coreutils 5.97-23 on CentOS. The current coreutils package is already up to coreutils 8.5 and upgrading coreutils is near impossible on CentOS because of other package requirements that it needs. Below are instructions on how to download the coreutils source, build the coreutils applications in a new directory, and then upgrade one application.