Note to self...

Discussion in 'NZ Computing' started by Lawrence D'Oliveiro, Jun 5, 2008.

  1. ....in future, do not use a Gentoo system as a critical central router in my
    office.

    I had the USB ADSL modem working off it, it was my Internet router, and also
    a DHCP server for my other machines. It had been running happily without
    interruption for some months. Then this evening there was a power failure
    for ten minutes, and when power came back on, I couldn't start up my ADSL
    any more.

    Looks like, in amongst all the software upgrades I had been doing over that
    time, I had managed to install a version of PPP without PPP-over-ATM
    support. The previous version I was running kept on running without a
    hiccup, but of course when it went to start up again, the ATM support
    module had gone. I wanted to look for a PPP-over-ATM module to install ...
    except of course I had no Internet connection that I could use to download
    the software to install.

    Yes, I could have resurrected the old D-Link which I had been using for my
    ADSL before, but there was one other option to try first.

    I moved the USB ADSL modem to my older Shuttle, which had a relatively safe,
    unexciting SuSE 10.2 installation on it. It got recognized and connected
    fine, and it took only a little massaging of the PPP configuration to get
    that running. So that machine, at least, was back on the Internet.

    Next step was to enable it as a router for the rest of my office. I checked
    some iptables settings--what's this? No NAT function available?

    OK, I'll admit it wasn't a completely vanilla SuSE installation. I'd
    replaced the kernel with a custom one, because the standard SuSE kernel has
    problems driving a Digium TDM400P telephony card. In configuring my kernel,
    I had neglected to select the necessary netfilter functionality--which of
    course I hadn't needed before. Recheck my kernel config--no option to
    select NAT? Checking the various Kconfig files, turns out you need to
    enable the netfilter connection-tracking option first, and _then_ that
    makes the NAT option available for selection.

    OK, reconfigure the kernel source, and rebuild the kernel (takes about 20
    minutes). Install it, reboot--and it can't find my hard drive. Couldn't
    load the driver module. Of course I'd forgotten to do a "make clean" to get
    rid of the outdated object files from before the configuration change. OK,
    do the make clean, build the kernel again, install it again.

    Now I have NAT. Execute the same script I used to set up the
    routing/firewall rules on the newer Shuttle--hit an error saying something
    like unable to match state/target combination. What now? Forgot to enable
    another netfilter kernel config option. Do that, do yet another kernel
    build. Install, reboot. Success! It can now do routing for my other
    machines.

    So I'm back on the air again. There's still the problem of that TDM400P
    card--I've rebuilt the zaptel driver against my new kernel, but it still
    won't load properly. I'll deal with that tomorrow--it's time for bed.

    And a good-night to all.
    Lawrence D'Oliveiro, Jun 5, 2008
    #1
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  2. Lawrence D'Oliveiro

    EMB Guest

    Lawrence D'Oliveiro wrote:
    > ...in future, do not use a Gentoo system as a critical central router in my
    > office.
    >
    > I had the USB ADSL modem working off it, it was my Internet router, and also
    > a DHCP server for my other machines. It had been running happily without
    > interruption for some months. Then this evening there was a power failure
    > for ten minutes, and when power came back on, I couldn't start up my ADSL
    > any more.
    >
    > Looks like, in amongst all the software upgrades I had been doing over that
    > time, I had managed to install a version of PPP without PPP-over-ATM
    > support. The previous version I was running kept on running without a
    > hiccup, but of course when it went to start up again, the ATM support
    > module had gone. I wanted to look for a PPP-over-ATM module to install ...
    > except of course I had no Internet connection that I could use to download
    > the software to install.


    In future TEST ALL UPGRADES/PATCHES BEFORE APPLYING THEM TO A CRITICAL
    SYSTEM. Don't blame Gentoo/Ubuntu/Suse/Windows/whatever, the problem is
    totally human in nature.
    EMB, Jun 5, 2008
    #2
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  3. In article <>, EMB did write:

    > In future TEST ALL UPGRADES/PATCHES ...


    On what?
    Lawrence D'Oliveiro, Jun 6, 2008
    #3
  4. Lawrence D'Oliveiro

    EMB Guest

    Lawrence D'Oliveiro wrote:
    > In article <>, EMB did write:
    >
    >> In future TEST ALL UPGRADES/PATCHES ...

    >
    > On what?


    A test system.
    EMB, Jun 6, 2008
    #4
  5. In article <4848d8cd$>, EMB did write:

    > Lawrence D'Oliveiro wrote:
    >
    >> In article <>, EMB did write:
    >>
    >>> In future TEST ALL UPGRADES/PATCHES ...

    >>
    >> On what?

    >
    > A test system.


    That's a circular statement.
    Lawrence D'Oliveiro, Jun 6, 2008
    #5
  6. Lawrence D'Oliveiro

    EMB Guest

    Lawrence D'Oliveiro wrote:
    > In article <4848d8cd$>, EMB did write:
    >
    >> Lawrence D'Oliveiro wrote:
    >>
    >>> In article <>, EMB did write:
    >>>
    >>>> In future TEST ALL UPGRADES/PATCHES ...
    >>> On what?

    >> A test system.

    >
    > That's a circular statement.


    How so?

    We have a development system in which we build apps.

    We then use a test system to check them for errors in a "production"
    environment by restoring a current backup of the live production system
    and then installing the new software and/or OS patches obnto that system.

    The test system then undergoes quite extensive functional and
    integration tests before being signed off as suitable for installation
    and use in the live system that runs the enterprise.

    Any migration of the changes to the live system are scheduled for a time
    when any unexpected outcomes (ie someone/something fucks up) will have
    minimal business impact, and a full team of technical staff are on call
    to ensure any problems can be rectified quickly.
    EMB, Jun 6, 2008
    #6
  7. In article <g28pme$b0j$>, Lawrence D'Oliveiro did write:

    > Looks like, in amongst all the software upgrades I had been doing over
    > that time, I had managed to install a version of PPP without PPP-over-ATM
    > support.


    I think I've figured out what happened. The Gentoo build for the "ppp"
    package by default does not include ATM support. I must have done a
    one-time override of the USE flags to include this (which the Gentoo folks
    recomment you _not_ do), and then forgotten I'd done so. So when the next
    version became available, and I upgraded, naturally it reverted back to no
    ATM support.

    It's OK, I've added an entry to my /etc/portage/package.use to make this a
    permanent setting. Though I still don't think I'll be moving the ADSL modem
    back to the Gentoo machine. :)
    Lawrence D'Oliveiro, Jun 13, 2008
    #7
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