TLS

Transport Layer Security

This page is mainly about adding Transport Layer Security TLS (also commonly referred to by it's predecessor 'Secure Sockets Layer or SSL') for your web servers such as Apache or nginx.

If you have a website or other online resources, you should be running them on a Secure webserver. If you need help, call eQuality Technology. We can secure your site very quickly and very cost-effectively, using the highest grade security measures.

Security Check

Instantly check your site's security grade at https://www.ssllabs.com/ssltest/analyze.html (you can also append the domain name like so: ?d=equality-tech.com)

Checking Ciphers

You can use nmap to port scan a host (Do NOT do this on hosts you don't control... it's like poking a hornets nest, you're not sure what's going to happen next but it could be bad). Use this particular invocation to show the SSL ciphers in use on your host. The description below is from /usr/share/nmap/scripts/ssl-enum-ciphers.nse)

This script repeatedly initiates SSL/TLS connections, each time trying a new cipher or compressor while recording whether a host accepts or rejects it. The end result is a list of all the ciphers and compressors that a server accepts.

Each cipher is shown with a strength rating: one of strong, weak, or unknown strength. The output line beginning with Least strength shows the strength of the weakest cipher offered. If you are auditing for weak ciphers, you would want to look more closely at any port where Least strength is not strong. The cipher strength database is in the file nselib/data/ssl-ciphers, or you can use a different file through the script argument ssl-enum-ciphers.rankedcipherlist.

SSLv3/TLSv1 requires more effort to determine which ciphers and compression methods a server supports than SSLv2. A client lists the ciphers and compressors that it is capable of supporting, and the server will respond with a single cipher and compressor chosen, or a rejection notice.

This script is intrusive since it must initiate many connections to a server, and therefore is quite noisy.

nmap --script +ssl-enum-ciphers example.com

Let's Encrypt

We used to run certificates from StartSSL because they offer free one-year certificates. However, today we upgraded to using 'LetsEncrypt' and our certificates are both more secure and easier to manage. Instead of a "B" grade, we now have "A" grade security.

Certbot (code) is a fully-featured, extensible client for the Let's Encrypt CA (or any other CA that speaks the ACME protocol) that can automate the tasks of obtaining certificates and configuring web servers to use them. This client runs on Unix-based operating systems. It requires root access and is beta software.

Until May 2016, Certbot was named simply letsencrypt or letsencrypt-auto, depending on install method. Instructions on the Internet, and some pieces of the software, may still refer to this older name.

Certbot website at EFF.org (the Electronic Frontier Foundation).

Service

Using our Ansible role, we can install the certbot client. Then we can install as many certificates as needed; plus setup an automated job which will renew them every 90 days.

Resources

Transport Layer Security
https://letsencrypt.org/getinvolved/ Get Involved with Lets Encrypt
1. https://letsencrypt.org/getting-started/ Getting Started
2. https://github.com/letsencrypt/letsencrypt Code on GitHub
3. https://letsencrypt.readthedocs.org/en/latest/ Docs
https://wiki.mozilla.org/Security/Server_Side_TLS
https://security.stackexchange.com/
Apache docs
Ubuntu Server Guide - Certificates and Security
Ansible role for LetsEncrypt

TLS