Azure Nibble - How to get TcpPing on Linux Azure App Service

Ping vs. TcpPing?

Ping is a computer network administration software utility used to test the reachability of a host on an Internet Protocol (IP) network using Internet Control Message Protocol (ICMP).

There can be instances where a remote host, has blocked ICMP traffic, which in turn means we cannot test/check to connectivity to the remote host. In this kind of a situation, what you can do to check the host's presence is to telnet to a known port or to try making a TCP connection to the host.

This is where tcpping comes in and is a TCP oriented ping alternative. It is used to test the reachability of a service on a host using TCP/IP and measure the time it takes to connect to the specified port. It is a very useful tool to help with diagnosing network related issues on Azure App Service.

Windows based app services in Azure automatically have tcpping enabled, however this valuable tool is missing on linux based app services, so in todays tutorial we will look at how we can get and run tcpping on linux based app services.

Installation

Go to your app service Kudu site: https://[sitename].scm.azurewebsites.net/webssh/host to establish a SSH web session. Or use the azure portal to navigate to the kudu site as follow:

Run the following:

1. apt-get install tcptraceroute (Required: if not already present.)
2. apt-get install bc (Required: if minimal Linux Runtime used, e.g. docker.)
3. cd /usr/bin
4. wget http://www.vdberg.org/~richard/tcpping
5. chmod 755 tcpping

How to use

tcpping [-d] [-c] [-r sec] [-x count] ipaddress [port]

• [-d]: print timestamp before each result.
• [-c]: use columned output for easy parsing.
• [-r]: interval in seconds between consecutive probes (1 second by default).
• [-x]: repeat n times (unlimited by default).
• [port]: target port (80 by default).

I hope you have enjoyed this post and have learned something new. ❤️

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