My posts about issues concerning Linux OS and network administration

Server administration

Monitoring postfix with Zabbix (LTS version 3.0)

Posted on:
Friday, May 6th, 2016
Author:
Tomas Brandysky

As we’ve built new monitoring system based on Zabbix LTS version 3.0 I also was looking for solution how to monitor postfix servers. I’ve found few articles regarding this issue but they were either outdated or not very effective. I decided to take the best from what I’ve found but build an own strategy. The […]

Posted in Monitoring | 4 Comments »

How to backup vSphere’s virtual machine configurations automatically

Posted on:
Tuesday, July 8th, 2014
Author:
Tomas Brandysky

We decided to setup some simple solution to backup configurations of all virtual machines in our virtualization cluster as this definitely could come in handy in case of data loss when these virtual machines would need to be restored along with their original configurations. I was searching for a simple solution on Internet for a […]

Posted in Backups, Server administration | 2 Comments »

Advanced Bacula management – getting rid of unused Bacula volumes

Posted on:
Wednesday, December 18th, 2013
Author:
Tomas Brandysky

I’ve been using Bacula software for couple of years in different companies and in different configurations. Bacula is a great and complex backup software which can compete with big commercial backup solutions in some ways but it also have some cons you have to deal with when implementing it in production environment. One of the […]

Posted in Backups | No Comments »

Synchronizing users from LDAP to Active Directory

Posted on:
Thursday, September 5th, 2013
Author:
Tomas Brandysky

Since we decided to implement Active Directory in our company to take control of user’s desktops there rose up the idea of synchronizing users between LDAP and AD. The optimal solution would be two-way synchronization between our LDAP server and Active Directory server including user login, email, full name and his password. After we had […]

Posted in Server administration | No Comments »

Custom maintenance page defined as an DNS record

Posted on:
Thursday, April 25th, 2013
Author:
Tomas Brandysky

If you are running a web page on server which needs to be taken down due to maintenace reasons you probably need to cope with unrachability of your page during the downtime. This is generally done by serving a simple maintenance page explaining the reasons of downtime and estimated time when the page will be […]

Posted in High availability, Server administration | No Comments »

LDAP replication with OpenLDAP 2.3 and Centos/RHEL 5

Posted on:
Thursday, April 25th, 2013
Author:
Tomas Brandysky

OpenLDAP version 2.3 comes with new LDAP Content Synchronization protocol which is described in RFC 4533 and is generally known as syncrepl. The older slurpd approach is obsolete and isn’t supported from OpenLDAP 2.4 Although syncrepl supports both master-slave and multi-master replications, there is only support for master-slave in OpenLDAP version 2.3 which also is […]

Posted in Server administration | No Comments »

How to debug crashing application on RHEL/Centos systems

Posted on:
Tuesday, April 23rd, 2013
Author:
Tomas Brandysky

We are running bunch of our applications on production Centos 5 servers and it happens sometimes that one of the processes crashes unexpectedly but not so often so that we could reproduce the behaviour and localize the problem. At this point having a possibility to turn on the debug mode in Linux definitely comes in […]

Posted in Server administration | No Comments »

AOL’s misconfigured SMTP servers bouncing emails with 521 error

Posted on:
Thursday, January 31st, 2013
Author:
Tomas Brandysky

We’ve fount out there is a problem with AOL SMTP servers that randomly reject emails with this hard error code: 521 5.2.1 “Service unavailable. Please try again later.” In fact this doesn’t happen very often and we may not have noticed something like that even happens if we hadn’t sent newsletters to our customers which […]

Posted in Server administration | 16 Comments »

Centos/RHEL 6 and authentication against LDAP with SSS approach

Posted on:
Friday, December 7th, 2012
Author:
Tomas Brandysky

There was a new approach of how to setup a LDAP authentication presented with RHEL 6. This new method called SSS is a replacement of pam_ldap. SSS states to be more flexible and also includes own caching mechanism which also means that NSCD daemon can’t be setup to cache the users/passwords once you run it […]

Posted in Server administration | No Comments »

Configuring OpenVPN authentication against LDAP (configured on Centos 5.8)

Posted on:
Tuesday, October 2nd, 2012
Author:
Tomas Brandysky

There is a possibility to configure OpenVPN server to authenticate users with additional login/password prompt. This can be used as an only user verification method or in additional to either standard pre-shared keys or certificates exchange configurations. We were using certificate authentication method in our company for a long time waiting to have LDAP configured […]

Posted in Server administration | 1 Comment »

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