Archive for 'Linux Networking'

Good write up Linux consistent network device naming

In RHEL 6.1 the default names assigned to Dell server network interfaces changed from ethX to emX and pXpX. The new names describe where a network interface physically resides in the system, and will have the following format: emX – the X (first, second, etc.) onboard interface pXpY – PCI device X port Y Dell […]

Speeding up SSH (SCP) data transfers

I’ll be the first to admit that I’m an SCP addict. It doesn’t matter what kind of data I’m working with, if it can be turned into an object that I move around with scp I’m in! One thing I’ve always noticed with scp is the dismal out of the box performance. I read quite […]

Using netstat and dropwatch to observe packet loss on Linux servers

Anyone that is running a modern Operating System is most likely utilizing TCP/IP to send and receive data. Modern TCP/IP stacks are somewhat complex and have a slew of tunables to control their behavior. The choice of when and when not to tune is not always super clear cut, since documentation and the advice of […]

Using the Linux arping utility to send out gratuitious ARPs

I managed a number of Redhat and Heartbeat clusters. On a couple of occassions the services that manage the virtual IPs have misbehaved, and the storage has ended up on one node and the virtual IP on another. To fix this I need to manually move the virtual IP to the host it belongs on, […]

Stopping your RHEL virtual interfaces from starting at boot. ONPARENT you say?

I recently debugged a pretty interesting problem with one of my clusters. When I rebooted one of the nodes, I noticed that a virtual interface that had ONBOOT set to no was started when the network interfaces were initialized. For those not familiar with RHEL systems, the ONBOOT directive tells the network initialization scripts not […]

How to learn everything you ever wanted to know about Linux sockets

Viewing network socket data is something SysAdmins do often. We could be called on to see if a connection is established to a host, if an application is listening on a given port, or we may need to review the network connection table as a whole to see what a server is doing (this is […]

« Older Entries