SBC to force all home DSL to PPPoE
mail-e-68e69c860e3a46b658 at kimihia.org.nz
Sun Aug 5 15:39:31 PDT 2001
Lewis E. Wolfgang wrote:
: two different domain names pointing at it. Given that I have
: DNS A records pointing to my @Home IP, how could I replicate
: that functionality with PPPoE? I've seen some ISP's take
: a full week to flush their DNS caches once an IP changed.
The components you need are:
1- Gadget to check for changed IP (eg, in your ppp scripts, if-up or
somewhere - I run it from cron every 15 minutes and compare it against
a stored value)
2- Gadget to update your zones
3- DNS server
The first step can be replaced with anything you like. Even something
$ echo 127.0.0.1
I wrote a little perl script that parses the output of the 'show ip if'
command on the modem. It finds the current IP of the external interface
and prints that to standard output which is then used by ...
The second bit is just sed + rsync. sed to create real zones from the
templates. rsync to copy them to the secondaries.
And for the final bit, a couple of mates running djbdns. There may be
people here that could help you with that, but I'll let them come forward.
Regarding flushing the DNS cache, you can set that yourself. In your DNS
zone you can specify a TTL (Time To stay aLive - I know it isn't the
correct expansion, but it isn't ambiguous this way). I set it to 300
seconds, which is the length of time between DNS reloads on the servers.
High enough to be useful to caches, low enough to not be a problem should
the IP change.
Stephen Cope - http://sdc.org.nz/
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