Month: September 2021

nmap scaning ciphers and ssl

Posted on by soban

Nmap – scanning SSL/TLS ciphers on Debian 11

In this example we are working on Debian 11 (Bullseye). First, let’s confirm the system version:

Nmap is one of the most powerful network scanning tools available on Linux. It allows you to scan open ports, detect running services, identify software versions and analyze supported SSL/TLS protocols and cipher suites.

Installation on Debian 11 is simple:

After installation, we can test a remote HTTPS server. For example:

The -sV option enables service version detection and --script ssl-enum-ciphers checks supported TLS versions and encryption ciphers. This allows you to verify which TLS versions are enabled (TLS 1.0, 1.1, 1.2, 1.3), whether weak ciphers like 3DES are supported and if potential cryptographic vulnerabilities exist.

Nmap is slower than tools like sslscan, but the level of detail is very good and useful especially for internal infrastructure testing.

TLS 1.0:

TLS 1.0 scan result using Nmap

TLS 1.1:

TLS 1.1 scan result using Nmap

TLS 1.2:

TLS 1.2 cipher suites detected by Nmap

The most important thing when analyzing SSL/TLS configuration is checking for weak or vulnerable ciphers. For example, if you see: “64-bit block cipher 3DES vulnerable to SWEET32 attack”, it means the server still supports 3DES, which is vulnerable to the SWEET32 attack. In production environments such ciphers should be disabled.

If you are testing a public website, you can also use https://www.ssllabs.com/ssltest/. However, for internal servers, staging environments or private infrastructure, using Nmap directly from your Debian system is often the best solution. Regular SSL/TLS scanning helps keep your infrastructure secure and ensures that outdated protocols and weak encryption methods are eliminated.

sslscan tool for scaning SSL

Posted on by soban

SSLScan is a command-line tool used for SSL/TLS vulnerability scanning. It is used to detect SSL/TLS vulnerabilities and weaknesses on servers that use SSL/TLS. SSLScan supports all SSL and TLS protocols and cipher suites, including new ones such as TLS 1.3.

SSLScan can be used to identify various SSL/TLS vulnerabilities, such as weak ciphers and encryption algorithms, insecure renegotiation, and Heartbleed attacks. It can also identify unsupported SSL/TLS versions and protocols, as well as expired or self-signed certificates.

SSLScan works by connecting to the target server and sending a series of SSL/TLS handshake messages to determine the supported protocols and cipher suites. It then checks for vulnerabilities and weaknesses by trying various attacks against the server, such as malformed SSL/TLS packets and invalid certificates.

SSLScan can be run from the command line and supports various options and flags to customize the scan. For example, it can be used to scan a specific port, specify the SSL/TLS version, or use a specific cipher suite.

Overall, SSLScan is a useful tool for checking SSL/TLS vulnerabilities and ensuring that servers are secure. It is commonly used by security professionals and system administrators to identify and mitigate SSL/TLS vulnerabilities on their networks.

In debian 11:

One of the best tool for scaning ssl is sslscan in Linux.
You can install on debian like this as root of course:

and than we can check for example google.com:

As you see, google use now tls 1.0, 1.1, 1.2 and 1.3:

Expired domain nginx

Posted on by soban

Script to help check if the domain is expiring (don’t forget change e-mail in script – now is soban@soban.pl):

This way you can download the script and give it permission to run:

And now we can add it to crontab, on monday for example: