Archive for October, 2010

DavMail CLI-only on a Seagate Dockstar running Debian

October 29, 2010

So I have Debian Squeeze running on a Seagate Dockstar… you can google around for this distro running on a 4-watt embedded device — I’m not going to explain it here.

I wanted to get DavMail running on it, so I went to install java packages. I ended up installing default-jre. But I had to update the package lists first — I ended up with some 404s on package names that had been renamed since my last update.

DavMail uses Java.SWT graphical elements by default. By setting davmail.server=true you can run it without an X11 display. All other items in your .davmail.properties can be default.

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Corporate relocation into network strangeness

October 27, 2010

At the old location we had a gateway for the automation network (172.30.x.x) with 2 NICs. One NIC was the 172.30.1.1 and the other NIC was just “another machine on the corporate network”. The IT guys defined for 172.30.x.x to get routed over the corporate network to our gateway… etc.

But then we got bought, and integrated our network into theirs. Fortunately they didn’t have machines on that IPv4 network already, but we still had to fight to preserve our subnet. Because changing over 1000 IPs is a real pain in the ass. (It shouldn’t be, but the implementation is not my choice or design.)

There’s some NAT involved now when we connect between the two networks.. anything from corporate shows up as 192.168.47.254 to the test systems. Can no longer uniquely identify who is logged on to the system :(

Now to the real issue. Since we moved in, some VNC sessions would just… reset over time. My ssh was fine. VNC sessions on *my* systems were fine. Wireshark led to nothing. Upon placing the mouse cursor back into the session, the VNC client would attempt to send a packet and the other end would RST. There was no traffic on the wire for a long time. The connection was dropped by the NAT/firewall.

Why is there no active traffic on those sessions, but on my sessions or ssh? Easy. A blinking cursor or the clock changing every minute generates enough traffic for the VNC session to stay alive – “keepalive traffic”. As for SSH, I’ve had “ServerAliveInterval 600” in my ~/.ssh/config ever since my first (public) server would kick out inactive connections after an hour.

I disabled the screensaver (merely a blanking of the screen for Linuxes) on the suspicious targets and the issue is “gone”.

Flat tire

October 21, 2010

I picked up my car from the shop in LA and went to Long Beach on Saturday night. Assumed 32 PSI all around and went driving around Long Beach and left for the Bay Area at 4pm. The light turned on around 6-7pm between Buttonwillow and Kettleman City (can’t remember). The light came on but I didn’t know the rate of deflation. I *think* the light comes on at 28 PSI, meaning I lost 4 PSI since the time that I hit the nail.

Work has been really busy as well so I didn’t address it for a full 48 hours.

Tuesday 12pm after parking at work, I see that it’s ridiculously flat, enough to warrant fairly immediate action. I actually waited until I got off at 8pm and my emergency kit measured about 10 PSI. At that low of pressure I don’t see any reliable readings. The other tires measured 32 (factory) and 32 at the gas stations (yes, I used 2), but 36 on my emergency kit, so I assumed my meter was +4. I also obtained another meter, with an offset of -1. I figured it was in the low 10s. I pumped it up to 34.

Wednesday morning at 10am, the light wasn’t on. That means it lost less than 6, assuming the light triggers at 28. However when I get off work at 7pm, the light turned on – confirmed the leak. I measured it at 26. In just about 24 hours, it lost 8 PSI.

Using this PSI deflation rate (which is totally inaccurate due to weather, road conditions, speed, etc) I tried to backtrace the series of events that led to this. Losing 4PSI in 12hours meant that I hit the nail Sunday morning around 6-7am, which is the time we went from the hotel to the marathon, which makes sense! So here’s an orderly (and probably errorful – deflation isn’t constant, etc) list:

  1. Sunday 6-7am (32 PSI): Hit nail
  2. Sunday 6-7pm (28 PSI): Light comes on
  3. Monday 10am: Estimated 23 PSI. The tire probably still looked normal at this point.
  4. Monday 9pm: Estimated 19 PSI. Too tired from work and too dark to see anything.
  5. Tuesday 12pm: Estimated 14 PSI. Obviously very flat, but not dead. I wait till off-work to address the issue. Too bad that doesn’t occur until 8pm…
  6. Tuesday 8pm: 12 PSI? no accurate reading at this point. Pump at Chevron (free) to “20”, but it doesn’t go further. Pump at Valero (it works!) to 34.
  7. Wednesday 10am: Light not on, so still above 28 PSI.
  8. Wednesday 7pm (26 PSI): Light on. Estimated 8PSI/12hours deflation rate to figure stuff out.