ddclient and wrong IP address

Luc484 · Veteran Joined: 26 Mar 2005 Posts: 1035 Location: Italy

Hi! It's been some time since I started to have this problem: it seems ddclient is not upgrading correctly my IP address. This is what I find in my logs:

Wormo · Posted: Wed May 21, 2008 1:59 am Post subject:

The warning does look pretty suspicious to me too.

Looking in the /etc/init.d/net.* scripts, see that they call themselves "inactive" if called in the background. So, it seems your net.ppp0 is getting called in the background, which could cause confusion if it was setting up the network in parallel with ddclient using network info. That would be a race condition, where a little change in timing (say faster response from the server ddclient talks to) might cause things to suddenly break.

Solution would be to enforce proper ordering by running net.ppp0 in the foreground so it finishes before ddclient gets to run. Do you know why net.ppp0 is currently running in the background -- do you have RC_PARALLEL_STARTIP enabled in conf.d/rc for instance?

Luc484 · Veteran Joined: 26 Mar 2005 Posts: 1035 Location: Italy

Well, I'm using baselayout 2 so I think RC_PARALLEL_STARTUP now is this:

Wormo · Posted: Wed May 21, 2008 6:59 pm Post subject:

Are you saying that you can start net.ppp0, wait until you see a new ip address and route established, now start ddclient, and ddclient still sees your previous dynamic ip??

If so, is your old ip still assigned as one of multiple ips, i.e. do you see both old and new when running 'ip addr list' ?

Luc484 · Veteran Joined: 26 Mar 2005 Posts: 1035 Location: Italy

Well, yes. That's what I'm saying. Look, here it is what I can do. This is my state with everything working:

PaulBredbury · Watchman Joined: 14 Jul 2005 Posts: 7310

Perhaps you need in /etc/sysctl.conf

Luc484 · Veteran Joined: 26 Mar 2005 Posts: 1035 Location: Italy

I changed it and rebooted. After the boot net.ppp0 was started and I checked with:

Wormo · Posted: Mon May 26, 2008 1:03 am Post subject:

Ok, this is a real puzzle. PaulBredbury's suggestion was a good one; too bad it didn't work.

If I were you, I would definitely be pulling out wireshark to do a couple of network captures: one for the situation where ddclient fails, and one where it works.

Luc484 · Veteran Joined: 26 Mar 2005 Posts: 1035 Location: Italy

Ok, I can do it, but what should I look for? I don't know how ddclient works. Where does ddclient take the current IP address? This is something I can't understand.

I noticed something else: if I try to set the IP manually using the web interface of dyndns.com, there is a link where you can click to set the current IP address which is determined some way, instead of manually writing it. That is wrong too, just like the one which is found by ddclient. Where is that IP taken from? Anyone knows?

Wormo · Posted: Mon May 26, 2008 6:33 am Post subject:

Luc484 · Veteran Joined: 26 Mar 2005 Posts: 1035 Location: Italy

Ok, this is strange, maybe I gave you wrong information. I just rebooted and now it seems connection is not working correctly. Maybe I was mistaken because I see that when I start pppoe net.ppp0 is started as well, maybe from some services. It is interesting because it seems incoming packets reach the ethernet layer but not ppp0. Systems behind NAT are working correctly but not Gentoo, which runs NAT. Wireshark shows no packet reaches ppp0 when using net.ppp0 (it seems some reach it, but only a few, I mean 1 per minute, no more, and the web is almost impossible to use). Using pppoe-start hundreds of packets reach ppp0.

If I try to use net.ppp0 and capture packets on eth0 I see the packets which go to ipdetect.dnspark.com and the source address is 192.168.1.3, which is the address of the interface eth0.

Wormo · Posted: Thu May 29, 2008 6:35 am Post subject:

It sounds like you've got something not quite right with your PPP configuration in /etc/conf.d/net, but /etc/ppp/pppoe.conf was set up correctly for the older PPoE method via ppoe-start, which still works for now (you've rp-ppoe installed right?)

Maybe you'd like to post the relevant section of conf.d/net ?

Luc484 · Veteran Joined: 26 Mar 2005 Posts: 1035 Location: Italy

I tried almost any possible configuration, this is what I have now:

mrness · Posted: Sun Jun 01, 2008 9:08 am Post subject:

Starting net.pppX only puts the service in the inactive state. Transitions between inactive to active states (and vice-versa) are performed by pppd through execution of /etc/ppp/ip-{up,down} scripts, scripts which are executed when the actual PPP link goes up/down.

Luc484 · Veteran Joined: 26 Mar 2005 Posts: 1035 Location: Italy

It seems those scripts can be executed without errors in the output. Does this mean those are ok?

mrness · Posted: Mon Jun 02, 2008 6:58 pm Post subject:

Those scripts must be executed with some parameters to actually do something. But you are not supposed to run them by hand; if you are curious when the scripts are executed and which code do they return, just add "debug" to your pppd_pppX.

Anyway, I don't think is anything wrong with your PPP link. I suspect you have a transparent web proxy between you and ipdetect.dnspark.com. If they also have their pages available through https, try to use this instead http.