Linux

I had an interesting design requirement for a network monitoring host. These monitoring hosts, or collectors, are used to monitor our network from an external perspective – via the Internet. They also needed to be reachable from our internal network for central management, and needed access to shared internal services, such as directory services, time servers, and central logging. Design My initial approach was to deploy the hosts in a public subnet, set the default route over the Internet, and add individual host routes via the transit gateway to the subnet routing table. This was not great from an operational perspective and violated the requirements when one of the statically-routed hosts also needed to be monitored externally. ...

I maintain a local mirror site for the Linux distributions we use. This is a simple rsync setup using ftpsync and Apache. I recently added Ubuntu to the list, but ran into an issue when I tested an automated install. The installer complained it was “Unable to locate package puppet.” In the preseed file, I tell the installer to also install this package with a pkgsel directive. (Later, using a late_command directive, the service is configured and started.) ...

Today I was doing some empirical testing of an application’s behavior when one of its authentication servers becomes unreachable. I typically do this with a null route on an upstream device, but noticed that iproute2 has this built in with a nice, memorable syntax. According to ip-route(8), one of the route types is blackhole: blackhole - these destinations are unreachable. Packets are discarded silently. The local senders get an EINVAL error. ...