Active Directory Authentication for SAS on Linux (with realmd)

This is another post in the series about configuring a SAS platform on Linux to use Integrated Windows Authentication (IWA), in this post I’m going to jot down some notes on steps 1-7 – configuring the Linux server for Active Directory (AD) Authentication.

Some time has passed since I wrote the original post, and a few things have changed. I’m now running SAS 9.4 M3, but this post should equally apply to SAS 9.4 M2. I have also switched the Linux distribution from Debian to CentOS 7.1. I am also using a much simpler method of joining the Linux server to the AD domain, using the realmd package (previously there were lots of individual steps using the underlying packages but realmd automates most of this). In this post I’m going to outline the simpler method using realmd of course.

Here goes … Continue reading “Active Directory Authentication for SAS on Linux (with realmd)”

IWA with SAS 9.4 M2 on Linux

I’ve just finished a challenging but very rewarding experience configuring a SAS 9.4 M2 platform on Linux to use Integrated Windows Authentication (IWA), for both server and mid-tiers ….. without using Quest Authentication Services.

The SAS platform has supported IWA on Linux since SAS 9.3 but until recently has only supported it when you “purchase, install, and configure an additional third-party product (Quest Authentication Services 4.0)”.

I’ve been wanted to do a SAS + Linux + IWA config for a while but had put it off because of the Quest requirement. What brought it back to the front of my mind was talking to someone recently about implementing IWA for a SAS Visual Analytics installation on Linux. They wanted to provide seamless login via IWA for most users, but also provide form-based logins for people who couldn’t use IWA.

I remembered seeing this section from the What’s New in SAS 9.4 (SAS 9.4 Intelligence Platform):

In the second maintenance release for SAS 9.4, Integrated Windows Authentication on Linux systems no longer requires the use of Quest Authentication Services. SAS can leverage the libraries that are shipped with the supported operating system or that are provided in most third-party authentication solutions.

It sounded like SAS 9.4 M2 would allow me to build such a config, without using Quest, and use the standard Linux libgssapi_krb5 package instead. At the same time I also remembered reading a great SAS Global Forum paper by Zhiyong Li on mid-tier fallback authentication: this is where you can configure the SAS mid-tier to fallback to form-based authentication in situations where IWA is not available or has been disabled (like you might do when you want to login using a different second identity). These both sounded like great challenges [ and fun 🙂 ], so I set about confirming my understanding of these possibilities with SAS 9.4 M2 by doing both at the same time.

After a few days of research, implementation, testing and debugging, I finalized the config last night. I got quite a buzz out of some of the mind-bending troubleshooting sessions and it was a very rewarding outcome. Other than a few relatively minor issues to resolve, it is all working very well now.

If I get some time I’ll try to write up a few blog posts with more detail on the steps, issues, troubleshooting techniques and resolutions. In the meantime here’s an outline of the approach I took:
Continue reading “IWA with SAS 9.4 M2 on Linux”

SAS & IWA: Check the Logs

When testing Integrated Windows Authentication (IWA) based client connections to SAS® platform servers, it is well worth checking the SAS logs to verify the connections are being made the way you expect. SAS has a variety of methods up it’s sleeve to get you authenticated, including cached credentials, retrieving stored credentials from metadata, SAS token authentication etc. Looking in the SAS server logs will help you identify the connection/authentication events and methods used. In the past I’ve thought I was using IWA+Kerberos but when I looked in the log it was obvious I wasn’t! I think it’s essential when testing/troubleshooting a new IWA configuration to review the SAS server logs for both failed and successful connections.

In a previous post “SAS and IWA: Two Hops” I mentioned how sometimes it’s necessary to force the use of Kerberos with IWA to be able to make IWA delegated connections to secondary servers. So here’s some examples of what we might see in SAS server logs Continue reading “SAS & IWA: Check the Logs”

SAS & IWA: Reviewing SPNs

My last post was about configuring additional Service Principal Names (SPNs) in Active Directory to support the use of Integrated Windows Authentication (IWA) in a SAS® platform installation that uses host name aliases in preference to physical host names.

When working on a SAS & IWA setup like this, I’d start by reviewing the currently registered SPNs for all of the SAS servers involved (as well as any other servers that might be accessed from a SAS server using IWA). This gives an idea of what SPNs might have already been added, which ones still need to be added, and potentially which ones might need to be removed.

This is the command I use Continue reading “SAS & IWA: Reviewing SPNs”

SAS & IWA: Host Name Aliases and SPNs

I’m quite keen on using host name aliases, rather than their physical host names, when referring to machines in SAS® platform installations. It does however mean a little extra configuration is required when using Integrated Windows Authentication. That is what this post is about: configuring Active Directory with additional Service Principal Names (SPNs) based on the aliases.

Host name aliases have several benefits over using physical host names. They can be easier to remember (e.g. sasmeta v.s. p106547). They can be easily redirected from primary environments to disaster recovery environments (e.g. sasmeta from p106547 to d106547) with no client reconfiguration requirements. They also allow host machines to be readily renamed if/when required with little or no changes to SAS configuration files, programs and/or metadata.

Whilst they have obvious benefits, Continue reading “SAS & IWA: Host Name Aliases and SPNs”