I like to travel, f*ck with technology, and partake in the occasional tropical drink.
I am also a co-host on The NBD Show podcast.
Follow Me


So the F5 is a tricky beast often refereed to as the swiss army knife of network appliances. The appliances primary role in many networks is to load balance and is a beast negotiating SSL. That being said its not always easy to determine how to configure the clients SSL profiles to be secure and still service the public. F5s documentation is helpful but designed to be vague because cipher suites and browser support is always changing. https://support.f5.com/csp/article/K8802


SSL Labs has become the de-facto to use tool that helps the public understand the nuances of SSL by giving an easy to understand letter grade, https://www.ssllabs.com . The website runs a multitude of tests from insuring your certificate is chained correctly to end device OS and browser simulations, to commonly found vulnerability testing. The down fall of having such a sophisticated tool issuing a simple letter score, is not every environment can be configured for an A or B plus.


So I wanted to through an F5 Client SSL Profile out there that at the time of testing got a solid A- and still supported a ton of OS and browser combinations. You will mostly want to keep the defaults but I will highlight what changes you will want to make to get an A. You will need to select Advanced to see some of these settings.

  • The first step is to add your public certificate and the intermediate certificates if applicable as well as the key.
    •  this is what create the certificates chain
  • Next you will want to customize the Ciphers that will be used by the F5 to negotiate SSL with the client. This is where 99% of the magic will happen.
    • DEFAULT:HIGH: (are pre canned cipher settings created by F5, the additional settings are additional customization.
    • !RSA: Do not use RSA ciphers
    • !SSLV3: Do not use SSL version 3
    • !RC4: Do not use RC4 ciphers
    • !EXP: Do not use Cipher length of 40 or 56 bits export strength
    • !DES: Do not use Des or triple Des ciphers
    • !TLSv1_1: Do not use TLS version 1.1
    • !TLSv1: Do not use TlS version 1.0
    • !ADH: Do not use ADH ciphers
    • !EXPORT: Do not use EXPORT grade (weak) ciphers
    • !SHA: Do not use Message Authentication Code SHA 128
  • The complete string looks like this:
  • Lastly you will want to set up strict SSL renegotiation:
    • Check the  Renegotiation box
    • Next set Secure Renegotiation to "Require Strict"


From here save your SSL client profile, apply it to a public accessible virtual server, and run SSL labs against your server. Its kind of fun testing and playing around to see what modifying the cipher settings.




I have noticed that after upgrading Ubuntu to 20.04 or 22.04 I have run into a little snag.  It appears that the upgrade over rights the sysctl.conf file back to default values. The symptom is your wiregurad server will not be forwarded IP V4 or V6 traffic. 
To resolve the issue perform the following steps.
  1. sudo nano /etc/sysctl.conf
  2. net.ipv4.ip_forward = 1
  3. sudo sysctl -p
WireGuard is a simple, fast, and secure VPN that utilizes state-of-the-art cryptography. With a small source code footprint, it aims to be faster and leaner than other VPN protocols such as OpenVPN and IPSec. WireGuard is still under development, but even in its non optimized state it is faster than the popular OpenVPN protocol. In fact it connects so quickly you'll likely find your self going to whats my IP to insure your traffic is actually being tunneled.

The WireGuard configuration is as simple as setting up SSH. A connection is established by an exchange of public keys between server and client. Only a client that has its public key in its corresponding server configuration file is allowed to connect. WireGuard sets up standard network interfaces (such as wg0 and wg1), which behave much like the commonly found eth0 interface. This makes it possible to configure and manage WireGuard interfaces using standard tools such as ifconfig and ip. I was going to post a guide but there are so many good guides already on the internet just google it. Also the official documentation is really good and has some install guides as well.

Enjoy, be safe, support and contribute to WireGuard.