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4-point checklist to update Centos 6 kernel with minimal server downtime

In our Server administration services, we perform a wide range of tasks from server hardening to service optimization. Kernel updates are vital in our services, especially in scenarios where a vulnerability or exploit make the servers susceptible to hacks.

We perform kernel updates in all Linux flavours, and the procedure varies with the type of the OS installed in the server and its version. If not done with proper planning and caution, a kernel update can mess up with your server.

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Upgrade CentOS 5 in your servers with Zero downtime

Upgrade CentOS 5 in your servers with Zero downtime

OS upgrades can get cumbersome at times, causing server down time or improper web site functioning. That is often the reason why some hosting providers shy away from upgrading their server OS in a timely manner.

But updating the server OS to the latest stable version is vital to protect it from hacks and vulnerabilities. That’s why, at Bobcares, our security experts stay alert to vulnerability updates and latest versions of all server software and applications. (more…)

How to fix error ‘Could not access KVM kernel module’ in Proxmox, Virtualizor, SolusVM, Redhat, CentOS and Ubuntu

How to fix error ‘Could not access KVM kernel module’ in Proxmox, Virtualizor, SolusVM, Redhat, CentOS and Ubuntu

KVM is a Linux virtualization technology that’s used in many virtualization solutions such as Proxmox, Virtualizor and SolusVM. All major Linux systems like RedHat, CentOS, Debian and Ubuntu have in-built support for KVM.

Bobcares helps VPS providers and server owners setup and maintain virtualization systems through our Server Management services. A common error found during the initial setup of KVM is “Could not access KVM kernel module“. (more…)

Identifying resource usage and performing migration to address performance issues in a Xen server virtualization environment

Identifying resource usage and performing migration to address performance issues in a Xen server virtualization environment

When Netflix faced an outage in 2011, they had to offer a 3% credit to their customers. The outage was due to a resource crunch in the Amazon cloud they were hosted in. It’s tough for a business to survive if such outages happen frequently.

A cloud hosting provider achieves economies of scale by sharing resources between multiple tenants in the cloud. These resources include computing, storage and network devices. But at times, the cloud provider may oversell the resources to achieve high-density or a single tenant can abuse the server resources. This can affect the performance of the cloud system. (more…)

DoS vulnerability in BIND DNS servers

DoS vulnerability in BIND DNS servers

On 28th July Internet Systems Consortium announced a critical vulnerability (CVE-2015-5477) in all BIND DNS server versions from 9.1.0 to 9.9.7-P1 and 9.10.2-P2. It allows a remote attacker to exploit an error in handling TKEY queries to launch a Denial of Service (DoS) attack which will cause the BIND DNS server to crash. (more…)

How to fix libuser root privilege and DoS attack vulnerability

How to fix libuser root privilege and DoS attack vulnerability

Qualys reported on 23rd July an important root privilege escalation vulnerability (CVE-2015-3246), and DoS attack vulnerability (CVE-2015-3245) for Linux servers using RedHat’s libuser package. Here’s how you can protect your CentOS and RedHat server from these vulnerabilities. (more…)