Wow. Thanks for the fast response. This is amazing.
No, I did not work for that station. I am in San francisco and was in elementary school during the 80s. What does fqdn mean and what is the authoritave server? On Thu, May 3, 2012 at 12:52 PM, Lawrence Statton <lawre...@cluon.com> wrote: > On 05/03/2012 12:25 PM, Terry Shepherd wrote: >> >> For a project at work, I need to have my development machine here at >> my house reachable via a name. >> >> I don't have static IP from my ISP (they offer it, but it's an >> expensive add-on). >> >> I have the router configured so that if you go to >> http://205.178.x../mypage you get to my server, but I need to have it >> reachable via http://somehost.mydomain.com/ >> >> How can I do this with PERL? I looked up "Dynamic DNS" on >> search.cpan.org and did not find anything that seemed appropriate. >> >> Thanks! >> > > Welcome, Terry. > > Did you work for KIXE-TV in the 80s? I knew a Terry Shephard ... or > Shepperd .. or I can't remember how he spelled his name. > > Anyway -- first things first: Perl or perl, *never* PERL :) (Perl is a > programming language, perl is the program that implements Perl, and PERL is > a brand of ant-poison.) > > Yes -- what you want is easily doable. There's a lot of work to getting it > to work, so I'll break it into pieces. > > First: I'm going to assume you're running Bind9 on your name server - I'm > sure there are other DNS implementations that will do it, but bind is the > one I know. If this is wrong - let me know and I'll see what I can do to > adjust my advice. > > On your name server, for the zone "example.com" you need to allow updates. > > It will look something like this: > > zone "example.com" IN { > type master; > allow-update { dyn-dns; }; > journal "/var/cache/bind/example.com.jnl"; > file "/etc/bind/pri/example.com"; > }; > > "dyn-dns" in the config file is the name of an ACL (Access Control List) > which defines "who is allowed to update this record" > > You create the Access Control List by adding something like: > > acl dyn-dns { > key dyn-dns-key; > }; > > > Which says "Any Update transaction signed with dyn-dns-key meets the > requirements of this access list". You may wish to add more constraints to > the Access List ( IP mask etc) depending on your needs. > > Next: You need to CREATE the key dyn-dns-key with a "key" directive. > > key "dyn-dns-key" { > algorithm hmac-md5; > secret "base-64-string"; > }; > > It's a base-64 string on my server, but I honestly can't remember if it MUST > be or if we just made a choice to do that. It might work just as well if > the shared secret is "fredddy-kreuger-is-not-a-nice-man" > > Okay -- now -- restart bind and check the logs (/var/log/daemon on my box - > your mileage may vary) > > NOW - We get to the Perl side. > > Install Net::DNS from CPAN > > The bits you will need are > > Net::DNS::Resolver - This is the object that encapsulate the DNS server. > > Net::DNS::Update - The object that encapsulates the changes. > > Read the doco for each of these,but they're pretty dense and difficult to > read if you don't have the DNS RFC(s) memorized. If you're like me, you'll > get lost in a sea of Resource Record Sets and Resource Records and ... > swoon. > > What you're going to do is create an "update" DNS request that says "Delete > all of the A records for somehost.mydomain.com. Add an A record for > somehost.mydomain.com. that points to 205.178.x.x. Sign that request with > my secret key." > > Then you're going to SEND that request to the Resolver (name server) and > (one hopes) check the return status. > > First - creating the Update request record. > > my $update = Net::DNS::Update->new('mydomain.com.'); > $update->push(update => rr_del('somehost.mydomain.com. A')); > $update->push(update => rr_add('somehost.mydomain.com A 205.178.123.123 > ')); > $update->sign_tsig(q(dyn-dns-key) => 'some-shared-secret'); > > Some "gotchas" to watch out for: > > * the constructor to Update wants the name of the domain the change is going > to happen in. > > * All of the records being added MUST use the fully-qualified-domain-name. > > * the NAME of the key (dyn-dns-key) MUST match the NAME of the key in the > ACL ... if you call it "my-secret-key" you must call it that in both places. > > Now - sending that record off to the server > > my $res = Net::DNS::Resolver->new; > $res->nameservers('fqdn.for.your.authoritative.name.server.net'); > > my $reply = $res->send($update); > > > > Finally - look at the reply status. > > If $reply is undef, you sent nothing, and you can find the reason in > $res->errorstring > > If $reply is defined, it you can get $reply->header->rcode > > If the change was accepted, it will be the string 'NOERROR' > > If there was something wrong, it ($reply->header->rcode) will be a (barely) > useful error message. > > Hope this gets you started down the path of writing some code.
