Category: Systems Admin

Topics dealing with servers – specifically setup and operation, in particular on Amazon’s cloud computing infrastructure.

Starting Varnish – Amazon’s Linux

I decided to install the new version of Varnish (3.0.1) using the Varnish repository (instead of amzn repository). The installation progressed without issue (you do need to override the default priorities of the repositories though), however, I ran into an issue trying to start Varnish. Every time I tried to start Varnish I would simply… Continue reading Starting Varnish – Amazon’s Linux

Building an Nginx RPM on Amazon’s Linux

If no customizations are desired, a far simpler way to get the RPM, than that outlined below, is to use the nginx repository, available from nginx’s download page. After deciding to change my server stack today (based on Amazon’s Linux), I noted that, despite the current version of Amazon’s Linux being hardly a few days… Continue reading Building an Nginx RPM on Amazon’s Linux

Upgrading Amazon’s Linux

Today, after looking over the changes in the new version of Amazon’s Linux AMI, I decided to upgrade (from 2011.02 to 2011.09). After running yum upgrade, I ran into an error (below) with compat-openldap. Error: Package: compat-openldap-2.4.19_2.3.43-15.11.amzn1.i686 (@upgrade-updates/2010.11) Requires: openldap = 2.4.19-15.11.amzn1 Removing: openldap-2.4.19-15.11.amzn1.i686 (@upgrade-updates/2010.11) openldap = 2.4.19-15.11.amzn1 Updated By: openldap-2.4.23-15.13.amzn1.i686 (amzn-main) openldap = 2.4.23-15.13.amzn1… Continue reading Upgrading Amazon’s Linux

Installing Heartbeat on Amazon’s EC2

I am currently working on setting up a small high availability server cluster on Amazon’s EC2 cloud. Such a setup requires several underlying technologies to work together. Common among these are a distributed file system, a load balancer, and some form of monitoring and resource control. This article looks at the one aspect of ‘monitoring’… Continue reading Installing Heartbeat on Amazon’s EC2

Rotating EBS Snapshots: ec2-prune-snapshots

Following the significant disruption of EBS volumes in April, the importance of backups was once again brought to the forefront. Amazon’s method of generating EBS backups is the ‘snapshot’ – a differential backup stored in S3. While Amazon provides tools for creating snapshots (either command line, or via their API), a script that is quite… Continue reading Rotating EBS Snapshots: ec2-prune-snapshots

Generating a pure-ftpd RPM for Amazon’s Linux

The only ftp server the amzn repository has is vsftpd. While, as the name suggests, vsftpd is supposed to be ‘very secure’ many other ftp servers have a comparable track record for security. Of these, pure-ftpd is easily configured and offers a wealth of features. Pure-FTPd is easily configured, and as it comes with an… Continue reading Generating a pure-ftpd RPM for Amazon’s Linux

ec2-consistent-snapshot on Amazon’s Linux AMI

Update: the complementary article to this one, on Rotating EBS snapshots has now been posted. After the recent failure of EBS volumes on Amazon’s cloud, backup is quite likely something to be considering. If, during the aforementioned incident, recent snapshots of the affected EBS volumes were available, it might have been possible to relaunch instances… Continue reading ec2-consistent-snapshot on Amazon’s Linux AMI

DKIM/Domainkeys signing via DKIMproxy

With the ever increasing volume of SPAM being transmitted, many email services look toward more elaborate ways to authenticate email. Beyond the obvious – content – two commonly used methods (perhaps with some variations), include sender policy framework (SPF), and DomainKeys Identified Mail (DKIM). Both of these require the use of DNS records to function.… Continue reading DKIM/Domainkeys signing via DKIMproxy

Setting up Subversion

Subversion is a versatile version control system. This article looks at how to set up subversion on Amazon’s Linux (RHEL/CentOS derived), and the necessary setup for using it with Apache (proxied through Nginx), as well as the setup of a repository, and the use of hooks to automatically update a live (non-production) working copy. Basic… Continue reading Setting up Subversion

Setting up NodeJS

It is quite unfortunate that one only has a finite number of hours to dedicate to learning new things, for inevitably there are things we skim over, or worse yet, don’t even know exist. Today, as I was looking for efficient ways of implementing server push for a project of mine, I came across NodeJS.… Continue reading Setting up NodeJS

Escalating Consequences with IPTables

I have previously written a bit about using IPTables to limit brute-force attacks. For the past month, that system has been working quite well. The typical attack pattern resembled that in [graph 1, graph2]. A few days ago, however, an attack was implemented which ‘fell under the radar’, so to speak – instead of being… Continue reading Escalating Consequences with IPTables