Category Archives: Computers

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Netgear LG 6100D LTE Gateway for Sprint Review – Bad Device, or the Worst Device?

  By Scott • 2014-08-25 , ,
Netgear Joke 9000

I recently obtained a Netgear LG6100D LTE Gateway from Sprint as a backup for my hard internet connections. The device seemed perfect on paper: Cellular connectivity for the home or business network! I’ve used some bad consumer routers in my day, but this is one of the worst I’ve encountered. Or maybe it’s that it looked so promising at first and then let me down so hard. Update (2014-08-26): I found that you can access the native Netgear web GUI. It has a heck of a lot more features, and solves many of the complaints I have with the “correct” way of configuring this device. Upon logging in the user interface is clean, fairly informative, and I noticed that the … Continue reading

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Oh, Pebble! You have a great product that’s being ruined by your support.

  By Scott • 2014-06-16 , ,
pebble_case_24XXXX_mq_sanitized

Two important things before I get started: I really like the original Pebble Smartwatch.  I’d probably like the Steel as well, but I haven’t tried it. I have a lot of respect for Pebble as a company.  It came into being through crowdsourced funding and actually delivered the product it promised. However, after about 6 months of ownership, my watch stopped vibrating.  Trying to resolve this issue was my first interaction with Pebble support, and hopefully will be my last.  Their process is slow, detrimental, and offensive. You may wonder at that last one:  “Offensive?” My gripe isn’t with the particular customer service person that handled my case.  (In fact I’ve redacted their name from this post.)   The CS … Continue reading

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Fix for: Keepalived router enters fault state on link down

  By Scott • 2014-06-06
keepalived_logo

TL;DR: This is the configuration option you want: dont_track_primary At work and at home I have pairs of redundant “core” routers in an active-passive (or master-backup as you like) configuration. They consist of commodity hardware, a few 4-port gigabit NICs, and CentOS. All of these machines had been running flawlessly for anywhere from two to six years (as they were put into service or upgraded). That is until yesterday when my primary router at home had an SSD failure which completely stopped it in its tracks. The backup router took over, and in less than a second traffic was being routed. All of my point-to-point VPNs reconnected within about 20 seconds. In other words, it worked exactly as it should. … Continue reading

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Redundant email servers with soft-fail (450) vs. hard-fail (550)

  By Scott • 2014-02-10
postfix_soft_fail

I manage a fairly large number of incoming mail exchangers, which are numerous both to handle large message volumes as well as to provide redundancy. In most cases, these mail servers are Postfix with MySQL providing virtual alias maps, transport maps, relay domains, and virtual alias domains. Unfortunately the Postfix+MySQL implementation isn’t always 100% great. On very rare occasions the Postfix instance may fail to communicate with the MySQL server, for any number of reasons. From the perspective of the sender’s MX, this usually results in a 550 status code (often given as “Relay access denied”). This is a hard-fail, in that it tells the upstream MX that the recipient they’re trying to reach is permanently unavailable. The upstream MX … Continue reading

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SAN with Linux Cluster and CLVM: Is it Necessary?

  By Scott • 2013-09-04
remove_clustering_services

To answer the title of this post in one word: No. But as with all things computer related, that “no” needs to be followed by the caveat: “Well, it depends upon your needs.” From what I’ve seen, Linux clustering was designed primarily for high-availability services, with only a secondary effort to share disk resources across nodes. I have tried — and would never use in production — Linux clustering services for a VM host cluster. I know other people have done it and will continue to do it, but a properly configured (and managed) VM cluster does not need true clustering. (Again, “depending upon your needs”). Linux clustering requires fencing. (It didn’t always, but now it does). Fencing is a … Continue reading

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Google Chrome Reports “Duplicate headers received from server”

  By Scott • 2013-06-10
Chrome Duplicate Headers Message

It seems that this error message has been around since version 16 of Chrome, and was first reported sometime in 2011. The error message basically says that it received two Content-Disposition headers, and that the response was blocked to prevent HTTP response splitting attacks. However, in most cases this error isn’t caused by malicious code, but rather because of an innocuous comma in the filename parameter of the Content-Disposition header. Here’s an example of an actual response header I received while downloading a resume from a popular career site: Content-Disposition: attachment; filename=Beresky_Resume,6pg.docx That was the only Content-Disposition header in the entire response, which raises the question: Why is this a duplicate header? Because according to the HTTP 1.1 specification, section … Continue reading

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Reducing Fan Noise from a Dell PowerEdge R905

  By Scott • 2013-06-08 ,
Images borrowed from the auction page of red_planet_trading on eBay

If you’re read my blog, you know that I have a quite a few servers in my basement that I use as a home lab environment. For home or low-demand virtualization, you can’t beat the Dell R905 for price. Consider that, as of the time I’m writing this post, you can get an R905 like I did with 128 GB of RAM for about $960. That’s only a little more than the cost of the RAM! That machine has 4x AMD Opteron 8356 quad-core CPUs @ 2.3Ghz and two built-in 10gbps ethernet ports (plus 2 gigabit ports), a PERC6i controller, dual PSUs, and a full enterprise DRAC. It’s a little old, but you can’t get those specs in any other … Continue reading

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Getting Started with Free CDN from KisoLabs

  By Scott • 2013-04-29
KisoLabs Homepage

When I was a teenager I had a basement full of computers. (Which is to say that my parents had a basement full of computers.) It was just a hobby at first, but computers eventually turned into an obsession and a profession for me. I liked every aspect of computers, from building hardware to networking to programming. Stay tuned for the bottom of this article where I’ve posted a referral code good for a $50 KisoLabs account credit. In those days (the mid- to late- 90s) DSL was the only way to get affordable static IPs, and I suffered with 192K SDSL (and later, 384K). Content was a lot lighter back then, but I was still suffering the same problems … Continue reading

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I propose a new approach to email reputation that allows the (legitimate) little guys to compete

  By Scott • 2012-09-28
spam_score_ss

I have a problem… I administrate roughly fifteen domains that send email on a regular basis.   Outbound email is handled by two corporate (and one personal) email servers running Zimbra and Exchange, as well as a couple of mail exchangers that handle automated email from web servers. I also don’t send spam.   All automated emails include a clear unsubscribe link, which is a single-click mechanism resulting in an immediate blacklisting of the user’s email address.  Automated emails also include the name and mailing address of the company from which they were sent, as per US federal law.  Corporate and personal emails are used responsibly;  In other words they are not used for blind solicitation nor for any other purposes … Continue reading

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Finding Out the IP Address of a New Piece of Tech from eBay

  By Scott • 2012-07-15
brocade_traffic_screencap

I’ve been through this many times over, and thought I would share:   I just bought a pair of HP Storageworks 4/8 SAN (AKA: Brocade Silkworm 200E) switches off of eBay.  They were listed as “powered up / as-is” by the seller, but the price was too good not to take a risk on them working properly. Of course, they came with no documentation, and not even a label to identify the IP address they held in their original home.  (I have had luck with other items where the IP and even login/password were labelled onto the front of the case). Most times, the following will work flawlessly: Connect your new piece of tech’s management interface (in this case, we’ll use … Continue reading