modem7/network-multitool

Network-Multitool

A (multi-arch) multitool for container/network testing and troubleshooting. The main docker image is based on Alpine Linux. There is a Fedora variant to be used in environments which require the image to be based only on RedHat Linux, or any of it's derivatives.

The container image contains lots of tools, as well as a nginx web server, which listens on port 80 and 443 by default. The web server helps to run this container-image in a straight-forward way, so you can simply exec into the container and use various tools.

The docker repository to pull this image is now: https://hub.docker.com/r/modem7/network-multitool

Or:

docker pull modem7/network-multitool

Supported platforms:

• linux/amd64
• linux/arm64

Downloadable from Docker Hub:

• https://hub.docker.com/r/modem7/network-multitool (An automated multi-arch build)

Variants / image tags:

• latest, alpine-minimal ( The main/default 'minimal' image - Alpine based )
• alpine-extra (Alpine based image - with extra tools )

Remember, this multitool is purely a troubleshooting tool, and should be used as such. It is not designed to abuse openshift (or any system's) security, nor should it be used to do so.

Tools included in "latest, alpine-minimal":

• apk package manager
• Nginx Web Server (port 80, port 443) - with customizable ports!
• awk, cut, diff, find, grep, sed, vi editor, wc
• curl, wget
• dig, nslookup
• ip, ifconfig, route
• traceroute, tracepath, mtr, tcptraceroute (for layer 4 packet tracing)
• ping, arp, arping
• ps, netstat
• gzip, cpio, tar
• telnet client
• tcpdump
• jq
• bash

Size: 16 MB compressed, 38 MB uncompressed

Tools included in "alpine-extra":

All tools from "minimal", plus:

• iperf3
• ethtool, mii-tool, route
• nmap
• ss
• tshark
• ssh client, lftp client, rsync, scp
• netcat (nc), socat
• ApacheBench (ab)
• mysql & postgresql client
• git

Size: 64 MB compressed, 220 MB uncompressed

How to use this image?

How to use this image in normal container/pod network ?

Docker:

$ docker run  -d modem7/network-multitool

Then:

$ docker exec -it container-name /bin/bash

How to use this image on host network ?

Sometimes you want to do testing using the host network. This can be achieved by running the multitool using host networking.

Docker:

$ docker run --network host -d modem7/network-multitool

Note: If port 80 and/or 443 are already busy on the host, then use pass the extra arguments to multitool, so it can listen on a different port, as shown below:

$ docker run --network host -e HTTP_PORT=1180 -e HTTPS_PORT=11443 -d modem7/network-multitool

Configurable HTTP and HTTPS ports:

There are times when one may want to join this (multitool) container to another container's IP namespace for troubleshooting, or on the host network. This is true for both Docker and Kubernetes platforms. During that time if the container in question is a web server (nginx, apache, etc), or a reverse-proxy (traefik, nginx, haproxy, etc), then network-multitool cannot join it in the same IP namespace on Docker, and similarly it cannot join the same pod on Kubernetes. This happens because network multitool also runs a web server on port 80 (and 443), and this results in port conflict on the same IP address. To help in this sort of troubleshooting, there are two environment variables HTTP_PORT and HTTPS_PORT , which you can use to provide the values of your choice instead of 80 and 443. When the container starts, it uses the values provided by you/user to listen for incoming connections. Below is an example:

$ docker run -e HTTP_PORT=1180 -e HTTPS_PORT=11443 \
    -p 1180:1180 -p 11443:11443 -d local/network-multitool
4636efd4660c2436b3089ab1a979e5ce3ae23055f9ca5dc9ffbab508f28dfa2a


$ docker ps
CONTAINER ID        IMAGE                     COMMAND                  CREATED             STATUS              PORTS                                                             NAMES
4636efd4660c        local/network-multitool   "/docker-entrypoint.…"   4 seconds ago       Up 3 seconds        80/tcp, 0.0.0.0:1180->1180/tcp, 443/tcp, 0.0.0.0:11443->11443/tcp   recursing_nobel
6e8b6ed8bfa6        nginx                     "nginx -g 'daemon of…"   56 minutes ago      Up 56 minutes       80/tcp                                                            nginx


$ curl http://localhost:1180
Praqma Network MultiTool (with NGINX) - 4636efd4660c - 172.17.0.3/16 - HTTP: 1180 , HTTPS: 11443


$ curl -k https://localhost:11443
Praqma Network MultiTool (with NGINX) - 4636efd4660c - 172.17.0.3/16 - HTTP: 1180 , HTTPS: 11443

If these environment variables are absent/not-provided, the container will listen on normal/default ports 80 and 443.

FAQs

Why this multitool runs a web-server?

Well, normally, if a container does not run a daemon/service, then running it (the container) involves using creative ways / hacks to keep it alive. If you don't want to suddenly start browsing the internet for "those creative ways", then it is best to run a small web server in the container - as the default process.

This helps you when you are using Docker. You simply execute:

$ docker run  -d modem7/network-multitool

The multitool container starts as web server - so it remains UP. Then, you simply connect to it using:

$ docker exec -it some-silly-container-name /bin/sh 

Why not use LetsEncrypt for SSL certificates instead of generating your own?

There is absolutely no need to use LetsEncrypt. This is a testing tool, and validity of SSL certificates does not matter.

Why use a daemonset when troubleshooting host networking on Kubernetes?

One could argue that it is possible to simply install the tools on the hosts and get over with it. However, we should keep the infrastructure immutable and not install anything on the hosts. Ideally we should never ssh to our cluster worker nodes. Some of the reasons are:

• It is generally cumbersome to install the tools since they might be needed on several hosts.
• New packages may conflict with existing packages, and may break some functionality of the host.
• Removing the tools and dependencies after use could be difficult, as it may break some functionality of the host.
• By using a daemonset, it makes it easier to integrate with other resources. e.g. Use volumes for packet capture files, etc.
• Using the daemonset provides a 'cloud native' approach to provision debugging/testing tools.
• You can exec into the daemonset, without needing to SSH into the node.