Cover V10, I04


New Messages

To: Arthur Donkers
Subject: VTun article (October 2000)

Arthur, If the samples of the packet dumps you have given in your VTun article for Sys Admin are real, then I would be very wary of the "encryption" offered by VTun. If you study the packets closely, you will see that the same data appears in the same location in all the packets you showed in your example. This indicates to me (I am no crypto-geek by any means) that the encryption used is a simple bit-swizzle and that with a small amount of effort the key could be extracted from the encrypted data using differential decryption allowing the packets to be decrypted.

Brett Lymn
Computer Systems Administrator

Dear Brett,

The packet dumps are real dumps!

I haven't studied the encryption of VTun that closely to be honest. I paid attention to the authentication part, which makes sure the password is never sent over the tunnel. I will take a closer look at the data encryption now, first by studying the source code.

I must confess that since writing this article, I switched over to IPsec (the FreeS/WAN implementation for Linux) for two reasons:

  • It is a standard and makes interoperation between different platforms and vendors a reality (I tested it between Linux and W2K)
  • It has a better crypto foundation that VTun.

Thanks for pointing this out, and I will investigate it. If I turn up anything interesting, I will let you know.

Arthur Donkers

From: David R. Thome (

Please let me know if you have covered this suggestion in a previous issue. I have a suggestion for very helpful article that I'd like to see in your publication.

For all UNIX platforms, show how an SA would (by using cron) go out and make copies of all critical config files as well as output from commands such as ioscan, sysinfo, dmesg, and critical Veritas commands, etc. Have the cron run them weekly and maybe compare previous weeks in attempt to show potential problems. Also if a server crashes or begins having problems, these files would be good references to compare to. Which system files should be available, which command out would be critical to always have on hand? Does this make sense? Have you had articles on this in the past?

Readers: I don't think Sys Admin has published an article on this topic. If anyone can help, please let me know. Thank you. --AA

From: Jeff Krintila (

I just got around to reading an older edition of your fantastic mag and thought I would offer an additional snippet of info to the letter from Nick Patetta (New Messages in August 2000) regarding "Building a Jumpstart Server for Solaris" (Sys Admin May 2000).

Patetta mentions two cluster-install options (SUNWCuser and SUNWCall). I use the SUNWCXall cluster instead (includes the OEM distribution). I have found that if you are going to be installing Oracle 8.1.6, you need this type of install. Hope someone finds this helpful.


Thanks for the information, Jeff. --AA

From: Victoria Sadoff (
Subject: Viagra: Keeping Services Running on BSD (February 2001)

I find the metaphor implicitly comparing servers with penises used in this article unneccessary, puerile, and unprofessional. Why detract from useful information with infantile drivel?

Victoria, Thank you for taking the time to write to Sys Admin. I appreciate all feedback from readers, and I regret that you found the script name chosen by the author of this article to be unprofessional and immature. Please accept my apology for any offense. --AA

From: Mark E. Dawson, Jr.
Subject: SA feedback

Thanks to fellow member of the AIX-L mailing list, Jonathan Tansley, it was brought to my attention that I made a technical error in my AIX Cloning article (Sys Admin March 2001). I mention in the article that the "mkszfile" command creates BOTH and The truth is that "mkszfile" only creates the file.

To customize the file, you must copy the example file from /var/adm/ras directory, then make your customizations to your copy of that file.

Thanks to Jonathan for bringing that error to my attention.

Mark E. Dawson, Jr.
Unix/Oracle Consultant

From: Ian Jones
Subject: SA feedback

Having just purchased your Feb. 2001 issue, I must tell you that I will not be looking for your next one at the bookstore. I could justify spending $6 on something that imparts useful information or is at least entertaining, but at a slim 80 pages it is quite a stretch.

One of the very few articles you did bother to include didn't even have the program listings (Spamivore). You must concede that a detailed walk-through of the functions in this CGI is fairly useless without the code that it describes. If you did it to save space for more content I would understand, but it seems more like you ran out ink and paper.

You need to get it together if you want to stay afloat. This was a pretty slim offering.

Ian, I appreciate your comments about the magazine and regret that you were unsatisfied with your purchase. In many cases, we do choose to run the code listings only on our Web site so that we can include more articles in the magazine. Our readers generally also find this the easiest way to make use of the code.

Also, the total number of editorial pages we can run every month is based on a number of factors. Basically, however, it boils down to a stated editorial-to-ad ratio that we must maintain. I hope this addresses your concerns, and I thank you for writing. --AA