Installing TcpPing on Azure App Service Linux

3 minute read | By Toan Nguyen

A useful tool to help with diagnosing network related issues on Azure App Service is TcpPing. Below are the steps for installing the tool for Debian and Alpine based Docker images.

Prerequisites

  • Your Web App must be running
  • If using a custom container, SSH access must be configured.

Installation - Debian

  1. Go to your Kudu site (i.e https://<sitename>.scm.azurewebsites.net/webssh/host) to SSH into your app.
  2. apt-get install tcptraceroute
  3. cd /usr/bin
  4. wget http://www.vdberg.org/~richard/tcpping
  5. chmod 755 tcpping
  6. apt install bc

Sample WebSSH Session

root@0723dbccc05e:/usr/bin# apt-get install tcptraceroute
Reading package lists... Done
Building dependency tree
Reading state information... Done
tcptraceroute is already the newest version.clear
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
root@0723dbccc05e:/usr/bin# cd /usr/bin
root@0723dbccc05e:/usr/bin# wget http://www.vdberg.org/~richard/tcpping
converted 'http://www.vdberg.org/~richard/tcpping' (ANSI_X3.4-1968) -> 'http://www.vdberg.org/~richard/tcpping' (UTF-8)
--2017-10-27 15:10:52--  http://www.vdberg.org/~richard/tcpping
Resolving www.vdberg.org (www.vdberg.org)... 94.142.246.140, 2a02:898:62:f6::8c
Connecting to www.vdberg.org (www.vdberg.org)|94.142.246.140|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 3510 (3.4K)
Saving to: 'tcpping.1'

tcpping.1           100%[=====================>]   3.43K  --.-KB/s   in 0s

2017-10-27 15:10:52 (258 MB/s) - 'tcpping.1' saved [3510/3510]

root@0723dbccc05e:/usr/bin# chmod 755 tcpping
root@0723dbccc05e:/usr/bin# tcpping
tcpping v1.7 Richard van den Berg <richard@vdberg.org>

Usage: tcpping [-d] [-c] [-C] [-w sec] [-q num] [-x count] ipaddress [port]

        -d   print timestamp before every result
        -c   print a columned result line
        -C   print in the same format as fping's -C option
        -w   wait time in seconds (defaults to 3)
        -r   repeat every n seconds (defaults to 1)
        -x   repeat n times (defaults to unlimited)

Installation - Alpine

  1. Go to your Kudu site (i.e https://<sitename>.scm.azurewebsites.net/webssh/host) to SSH into your app.
  2. apk update
  3. apk add tcptraceroute
  4. cd /usr/bin
  5. wget http://www.vdberg.org/~richard/tcpping
  6. chmod 755 tcpping
  7. If you receive an error “cannot find bc. Install bc package:” use, apt install bc

Sample WebSSH Session

  _____
  /  _  \ __________ _________   ____
 /  /_\  \___   /  |  \_  __ \_/ __ \
/    |    \/    /|  |  /|  | \/\  ___/
\____|__  /_____ \____/ |__|    \___  >
        \/      \/                  \/
A P P   S E R V I C E   O N   L I N U X

Documentation: http://aka.ms/webapp-linux

**NOTE**: No files or system changes outside of /home will persist beyond your application's current session. /home is your application's persistent storage and is s
hared across all the server instances.


79eaacc1cd21:/home# apk update
fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/community/x86_64/APKINDEX.tar.gz
v3.12.7-75-gb976e2d90a [http://dl-cdn.alpinelinux.org/alpine/v3.12/main]
v3.12.7-63-gd5f321e0c1 [http://dl-cdn.alpinelinux.org/alpine/v3.12/community]
OK: 12767 distinct packages available
79eaacc1cd21:/home# apk add tcptraceroute
(1/3) Installing libnet (1.1.6-r3)
(2/3) Installing libpcap (1.9.1-r2)
(3/3) Installing tcptraceroute (1.5b7-r2)
Executing busybox-1.31.1-r19.trigger
OK: 224 MiB in 71 packages
79eaacc1cd21:/home# cd /usr/bin
79eaacc1cd21:/usr/bin# wget http://www.vdberg.org/~richard/tcpping
--2021-06-17 18:00:09--  http://www.vdberg.org/~richard/tcpping
Resolving www.vdberg.org (www.vdberg.org)... 136.144.244.145, 2a01:7c8:d006:f0::1
Connecting to www.vdberg.org (www.vdberg.org)|136.144.244.145|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 3510 (3.4K)
Saving to: 'tcpping'

tcpping             100%[===================>]   3.43K  --.-KB/s    in 0s

2021-06-17 18:00:09 (446 MB/s) - 'tcpping' saved [3510/3510]
79eaacc1cd21:/usr/bin# chmod 755 tcpping
79eaacc1cd21:/usr/bin# tcpping
tcpping v1.7 Richard van den Berg <richard@vdberg.org>

Usage: tcpping [-d] [-c] [-C] [-w sec] [-q num] [-x count] ipaddress [port]

        -d   print timestamp before every result
        -c   print a columned result line
        -C   print in the same format as fping's -C option
        -w   wait time in seconds (defaults to 3)
        -r   repeat every n seconds (defaults to 1)
        -x   repeat n times (defaults to unlimited)

See also: man tcptraceroute

79eaacc1cd21:/usr/bin#

TIP

In certain scenarios where the WebApp/container is unable to start or SSH is not configured in the Custom Docker Image, you could use tcpping tool from the Kudu Container. The Kudu container is used for build purpose and has tcpping pre-installed. You can SSH into the Kudu Container via: https://[webappname].scm.azurewebsites.net/newui/kududebug

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