Networking on smcleod.net

Broadcom, Or How I Learned To Start Worrying And Drop The Packet

Fri, 13 Oct 2017 00:00:00 +0000

Earlier this week we started the process to upgrade one of our hypervisor compute clusters when we encountered a rather painful bug with HP’s Broadcom NIC chipsets.

We were part way through a routine rolling pool upgrade of our hypervisor (XenServer) cluster when we observed unexpected and intermittent loss of connectivity between several VMs, then entire XenServer hosts.

The problems appeared to impact hosts that hadn’t yet upgraded to XenServer 7.2. We now attribute this to a symptom of extreme packet loss between the hosts in the pool and thanks to buggy firmware from Broadcom and HP.

Speeding Up rsync

Tue, 03 May 2016 00:00:00 +0000

The most common way to use rsync is probably as such:

rsync -avr user@<source>:<source_dir> <dest_dir>

Resulting in 30-35MB/s depending on file sizes

This can be improved by using a more efficient, less secure encryption algorithm, disabling compression and telling the SSH client to disable some unneeded features that slow things down.

With the settings below I have achieved 100MB/s (at work between VMs) and over 300MB/s at home between SSD drives.

Replacing Junos Pulse with OpenConnect

Tue, 22 Sep 2015 00:00:00 +0000

In an attempt to avoid using the Juniper Pulse (Now Pulse Secure) VPN client we tried OpenConnect but found that DNS did not work correctly when connected to the VPN. This bug has now been resolved recently but has not made it’s way into a new build, in fact there have been no releases for 6 months.

Luckily the OpenConnect was not too difficult to build from source.

Build OpenConnect on OSX

Remove old openconnect and install deps

brew remove openconnect
brew install libxml2 lzlib openssl libtool libevent

Build openconnect

wget git.infradead.org/users/dwmw2/openconnect.git/snapshot/0f1ec30d17aa674142552e275bf3fac30d891b39.tar.gz
tar zxvf 0f1ec30d17aa674142552e275bf3fac30d891b39.tar.gz
cd openconnect-0f1ec30

LIBTOOLIZE=glibtoolize ./autogen.sh
PATH=/usr/local/opt/gettext/bin:$PATH
./configure
make
make install

To connect

sudo openconnect --juniper -u myusername www.myserver.com

If you’re comfortable with allowing admin users to run openconnect without entering a sudo password, add the following using sudo visudo: