Tag Archives: MySQL

BIND 10: Configuring DHCP for DHCPv4 Clients

The fourth article in my series covering BIND 10 has nothing to do (directly) with DNS. This one describes how to configure the DHCP4 component of BIND 10 to provided DHCP service for IPv4 clients in my lab network. I used bind10-1.0.0-rc.

There is quite an important caveat to note from the RC release notes:

As you can see, DHCPv4 clients must be connected to the DHCP server via a relay. As I have no Cisco devices on my home network running ip-helper or similar, I used dhcrelay to provide DHCP relay services. I configured my network as per the following diagram, utilising three CentOS 6.3 x86_64 VMs:

b10-dhcp4

gooby will provide DHCP service to the 192.168.172.0/24 network via its eth1 interface. spooderman‘s dhclient will come online and make a multicast discovery request. dhcrelay on gooby will relay that message out of eth0 to dolan and b10-dhcp4. b10-dhcp4 will assign an IP address based upon configuration and current leases, and hand the offer back to gooby. dhcrelay will receive this offer, and relay it back out over eth1 via broadcast. spooderman will pick up this offer, and acknowledge it. Once b10-dhcp4 receives the acknowledgment, it commits the lease to the MySQL database. dhclient configures spooderman‘s eth0 interface, and the exercise is complete.

As 172.16.18.0/24 is my NATted network out of my test workstation, VMware provides its own DHCP service on the host OS - ensure this is shut down prior to commencing work. If your networks do not already run a DHCP service, you don’t need to worry about that - if they do, shut them down before proceeding (as long as this isn’t production :/) …

With the network planned and any existing DHCP services disabled, we can continue.

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Secure MySQL Replication over SSL

MySQL is a popular open-source relational-database management system. One of its core features is replication, and in this article I will be showing how to configure a master and slave MySQL instance, and then configure replication from master to slave over SSL. Encryption will help protect the replication from snooping. This type of replication has many uses, for example: disaster-recovery scenarios whereby the slave can be switched to a master role in the case of a master outage, for performance where all reads can take place on the slave with writes and updates occurring on the master, and so on. Replication can be configured without encryption, but encrypting with SSL is preferred as part of a defence-in-depth strategy - it’s an extra layer of security.

This article already presumes a good working knowledge of MySQL. The master server is centosa with IP address 10.1.1.150, and is running a minimal installation of CentOS 6.4 x86_64. The slave, centosb, is running the same OS and has IP address 10.1.1.151. MySQL will be installed from the latest current stable RPMs available at dev.mysql.com, rather than using the upstream versions. The latest stable version available at the time of writing is 5.6.14.

This article will cover the configuration of an SSL-encrypted replicated environment from scratch - it does not cover the migration of an existing replicated configuration to an SSL-encrypted replicated configuration, or the migration of any existing data to a new slave.

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MySQL Cluster: Adding New Data Nodes Online

MySQL Cluster has a pretty cool feature that allows you to add new data nodes whilst the cluster is online, thus avoiding any downtime. This is incredibly useful for scaling out the data nodes and adding additional node groups. In this article, I’ll show how to add two new data nodes to an existing cluster that has two data nodes defined. I’ll also explain what needs to happen after the configuration change to ensure that any existing data is correctly partitioned across the new nodes.

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