Comments for Andrew's personal weblog

Comment on High availability of services with ZABBIX and DNS failover by Scott McDonald

Scott McDonald — Wed, 24 Nov 2010 16:17:09 +0000

Andrea – the DNS updates flow through mysql replicaton. Powerdns has a “native” mode that can be used with the mysql backend. When zabbix detects an outage, it updates the RR directly in one of two mysql master servers. Those masters have power dns running in “native” mode. Each one of my masters then has several slave servers, that pull a slave only mysql replicaton feed, with powerdns running locally on them hitting their slave database in native mode. The system does not depend on notify or AXFR methods – but depends on changes to the database backend propagated through mysql replication to the various name servers. I then configured powerdns to key off the priority field with a custom resolver query… an A record with a value equal to or greather than 0 gets resolved by powerdns, an A record with a value less than 0 is not resolved by powerdns. One of my zabbix servers simply updates the the priority field column in the powerdns record to place it in or out of service (created triggers to fire when sites go down and when they come back up). The updates flow to all of the dns servers through replication almost instantly.

The whole system is dependent on keeping mysql replication working smoothly which is easy with zabbix monitoring. I setup zabbix to monitor replication status on all dns servers closely. I’ve worked in high volume environments pushing tremendous amounts of data through mysql replication farms and trust it completely in this DNS scenerio with much smaller replication volumes.

Thanks,
-Scott

Comment on High availability of services with ZABBIX and DNS failover by Andrea Valsania

Andrea Valsania — Tue, 09 Nov 2010 20:09:24 +0000

Yes, I thought to use the “remote command” operation type too, but it can only make a ZABBIX agent to launch a script, which is not what I was looking for (even if I could run an agent on the server itself).
Obviously my need is “specular” to yours: in my case the ZABBIX server and authoritative DNS servers are behind my ISP-failover enabled firewalls, and I aimed to run the nsupdate command by using as few pieces as possible, considering every further bit a source of unreliability.
By using this approach I only have two possible failure elements: the ZABBIX server process and the dynamic DNS server… both of whom I’m pretty confident with!

Your service seems to be pretty well designed. The only thing I don’t understand well is about the update method: you change the zone data by updating the RR directly in the MySQL database, and then you rely on standard DNS notify and AXFR methods to replicate to other name servers?

Comment on High availability of services with ZABBIX and DNS failover by Scott McDonald

Scott McDonald — Tue, 09 Nov 2010 19:10:28 +0000

Thanks for sharing your script. I had considered this approach a couple months back but took a different path.

Zabbix also has Actions which can be used to call external scripts and pass arguments. This combines nicely with PowerDNS when using a native mysql backend (with mysql replication to redundant name servers). Zabbix monitors site IPs and when it detects an outage or unacceptable response time triggers an action script. In my setups the action scripts verifies the outage from other Zabbix server locations – then modifies mysql dns records which replicate and almost instantly change the DNS resolutions from geographically distributed powerdns servers. I’ve used this approach to provide automated DNS failover, failback, and loadbalancing for several large clients in the past (and this is the combination I settled on using as the engine for my startup company http://www.cnamefailover.com).

Comment on CommuniGate VoIP services by Esteban Reveal

Esteban Reveal — Sun, 08 Aug 2010 09:55:49 +0000

Interesting that a few years back people were questioning the viability of VoIP (ie. Vonage fiasco). Now everywhere you turn its widely accepted and has become very established.

Comment on New Cisco router by Nicole

Nicole — Wed, 21 Apr 2010 09:41:58 +0000

Not new lol,……

Comment on wpDirAuth 1.4 patch by Trm

Trm — Fri, 25 Sep 2009 10:26:42 +0000

Sorry to bother, I actually fixed my issue by editing the line
“elseif ($userID = wp_create_user($userLogin, $password, $userEmail)) {” by adding the users_can_register option verification like this =
“elseif (($userID = wp_create_user($userLogin, $password, $userEmail)) && ( get_option(‘users_can_register’) ) ) {”
Hope this helps other users

Comment on wpDirAuth by Trm

Trm — Thu, 24 Sep 2009 19:57:19 +0000

Hello, I’ve been using the plugin successfully, but now I’m facing an issue, I would like to disable user registration, I mean I have all my necessary ldap users already subscribed, and don’t want other random ldap user to subscribe anymore, I thought that just de-activating the option to register in WP would be enough, but it isn’t, every user from my ldap can still subscribe, if I deactivate wpdirauth plugin, nobody can enter the WP admin panel no more, so I’m desperately seeking a solution, and can’t find any support (the google group isn’t working anymore), thank you if you can help me !

Comment on wpDirAuth 1.4 patch by Andre

Andre — Tue, 31 Mar 2009 11:56:43 +0000

I’m not working with WP 2.7, when I try to login it shows me this error message:

Directory Login Error:
wpDirAuth config error: No directory server available for authentication, OR pre-binding credentials denied.

I try to hack the code and add a custom connection string “uid=username,ou=people,dc=domain,dc=com” which has worked but now I have the followed message:

Directory Login Error: Could not authenticate user. Please check your credentials. [user_xpto]

Any hints?

Comment on wpDirAuth versions by Delta Phi

Delta Phi — Mon, 16 Mar 2009 08:42:24 +0000

wpDirAuth-Versionen…

wpDirAuth ist ein aeussert praktisches Plugin, um WordPress-Accounts aus LDAP zu beziehen. Leider scheint sich der urspruengliche Entwickler, Stephane Daury, nicht mehr um das Plugin zu kuemmern. Somit verfaellt also seine Projektseite, die WordPress E…

Comment on wpDirAuth 1.4 patch by tina

tina — Mon, 16 Mar 2009 02:50:13 +0000

thank for your sharing