Macbook: Fixing the Wireshark Permissions bug “You don’t have permission to capture on that device”

If you see the error “The capture session could not be initiated on the device “en0″ (You don’t have permission to capture on that device)” when trying to start a pcap on wireshare you can try installing ChmodBPF; but I suspect you will need to follow the steps below:

$ whoami
$ cd /dev
/dev $ sudo chown superman:admin bp*
$ ls -la | grep bp
crw-------   1 cp363412  admin     0x17000000 Jan 13 21:48 bpf0
crw-------   1 cp363412  admin     0x17000001 Jan 14 09:56 bpf1
crw-------   1 cp363412  admin     0x17000002 Jan 13 20:57 bpf2
crw-------   1 cp363412  admin     0x17000003 Jan 13 20:57 bpf3
crw-------   1 cp363412  admin     0x17000004 Jan 13 20:57 bpf4
/dev $

Linux: Automatically renew your certs for a wordpress site using letsencrypt

If you want to automatically renew your certs then the easiest way is to setup a cron just to call letsencrypt periodically. Below is an example cron job:

First create the bash script to renew the certificate

$ pwd
$ sudo nano

Now enter the script in the following format into nano:


sudo /opt/bitnami/ stop apache
sudo /opt/bitnami/letsencrypt/lego --path /opt/bitnami/letsencrypt --email="" --http --http-timeout 30 --http.webroot /opt/bitnami/apps/letsencrypt renew --days 90
sudo /opt/bitnami/ start apache

Now edit the crontab to run the renew script:

$ crontab -e
0 0 * * * sudo /home/bitnami/ 2> /dev/null

A simple DDOS SYN flood Test

Getting an application knocked out with a simple SYN flood is both embarrassing and avoidable. Its also very easy to create a SYN flood and so its something you should design against. Below is the hping3 command line that I use to test my services against SYN floods. I have used quite a few mods, to make the test a bit more realistic – but you can also distribute this across a few machines to stretch the target host a bit more if you want to.


-c –count Stop after sending (and receiving) count response packets. After the last packet was sent, hping3 wait COUNTREACHED_TIMEOUT seconds target host replies. You are able to tune COUNTREACHED_TIMEOUT editing hping3.h

-d –data data size Set packet body size. Warning, using –data 40 hping3 will not generate 0 byte packets but protocol_header+40 bytes. hping3 will display packet size information as first line output, like this: HPING (ppp0 NO FLAGS are set, 40 headers + 40 data bytes

-S –syn Set SYN tcp flag

-w –win Set TCP window size. Default is 64.

-p –destport [+][+]dest port Set destination port, default is 0. If ‘+’ character precedes dest port number (i.e. +1024) destination port will be increased for each reply received. If double ‘+’ precedes dest port number (i.e. ++1024), destination port will be increased for each packet sent. By default destination port can be modified interactively using CTRL+z.

–flood send packets as fast as possible, without waiting for incoming replies. This is faster than the -i u0 option.

–rand-source This option enables the random source mode. hping will send packets with random source address. It is interesting to use this option to stress firewall state tables, and other per-ip basis dynamic tables inside the TCP/IP stacks and firewall software.

apt-get update
apt install hping3
hping3 -c 15000 -d 120 -S -w 64 -p 443 --flood --rand-source <my-ip-to-test>

External k8gb presentation to Kubernetes SIG multicluster

Today I am a happy bunny!!!! Yury Tsarev (a very clever dude) did a presentation to one of the Kubernetes co-founders Tim Hockin. The demo was one of absa banks opensource projects called K8GB (a cloud native GSLB for K8s):

Why do I like K8GB? Because it uses a single CRD that integrates to all the big DNS providers (like NS1, Infoblox and Route 53), it then uses zone delegation to allow the developers to manage their GTM in a single CRD. It also has native health checks using the liveliness and readiness kubernates probes (rather than just IMCP or http responses). Put simply it saves a whole bunch of unnecessary yak shaving!

So, if you have a few minutes you can watch the video (the demo starts after 10mins or so):

GIF so happy - animated GIF on GIFER