tlslookup command not found

Introduction

When you run more command in linux terminal / console, you get the following error message

tlslookup: command not found

or when using sudo you get the following error message

sudo: tlslookup: command not found

Solutions to tlslookup: command not found

How To Fix tlslookup: command not found in Ubuntu / Debian / Kali Linux / Raspbian

In Ubuntu tlslookup is provided by tlslookup package.

tlslookup is:

nss-tls is an alternative, encrypted name resolving library to use with glibc, which uses DNS-over-HTTPS (DoH).

The glibc name resolver can be configured through nsswitch.conf(5) to use nss-tls instead of the DNS resolver, or fall back to DNS when nss-tls fails.

This way, all applications that use the standard resolver API (getaddrinfo(), gethostbyname(), etc’), are transparently migrated from DNS to encrypted means of name resolving, with zero application-side changes and minimal resource consumption footprint. However, nss-tls does not deal with applications that use their own, built-in DNS resolver.

This package contains the utility program to lookup DNS names using libnss-tls.

To fix this problem, we can install more using the command below.

sudo apt-get -y install tlslookup

This command might take some time to finish depending on your machine internet connection.

You can also use apt command to install tlslookup.

sudo apt -y install tlslookup

Or if you have aptitude installed you can use the following command.

sudo aptitude install tlslookup

Summary

In this tutorial we learn how to fix tlslookup command not found error in Ubuntu / Debian / Kali Linux or Raspbian distribution.