From d48cb0050b6483c8d3367ffa3c20171b489f112c Mon Sep 17 00:00:00 2001
From: Simon Kuenzer <simon@unikraft.io>
Date: Wed, 3 Sep 2025 21:47:38 +0200
Subject: [PATCH] feat(netutils): An Alpine-based image having SSH and net CLI
 utils

Signed-off-by: Simon Kuenzer <simon@unikraft.io>
---
 netutils/Dockerfile   | 21 +++++++++++++++++++++
 netutils/Kraftfile    | 12 ++++++++++++
 netutils/README.md    | 37 +++++++++++++++++++++++++++++++++++++
 netutils/dropbeard.sh | 18 ++++++++++++++++++
 netutils/motd         | 20 ++++++++++++++++++++
 netutils/profile      |  1 +
 6 files changed, 109 insertions(+)
 create mode 100644 netutils/Dockerfile
 create mode 100644 netutils/Kraftfile
 create mode 100644 netutils/README.md
 create mode 100755 netutils/dropbeard.sh
 create mode 100644 netutils/motd
 create mode 100644 netutils/profile

diff --git a/netutils/Dockerfile b/netutils/Dockerfile
new file mode 100644
index 00000000..8da0e7f6
--- /dev/null
+++ b/netutils/Dockerfile
@@ -0,0 +1,21 @@
+FROM alpine:latest
+WORKDIR /
+
+RUN set -xe; \
+    apk update; \
+    apk add --no-cache \
+        socat \
+        dropbear \
+        tcpdump \
+        iputils \
+        traceroute \
+        bind-tools \
+        socat
+
+RUN echo "root:unikraft" | chpasswd
+
+COPY ./motd /etc/motd
+COPY ./profile /etc/profile
+
+RUN mkdir -p /opt/unikraft
+COPY ./dropbeard.sh /opt/unikraft/dropbeard.sh
diff --git a/netutils/Kraftfile b/netutils/Kraftfile
new file mode 100644
index 00000000..ae2fe410
--- /dev/null
+++ b/netutils/Kraftfile
@@ -0,0 +1,12 @@
+spec: v0.6
+
+runtime: base-compat:latest
+
+labels:
+  cloud.unikraft.v1.instances/scale_to_zero.policy: "off"
+  cloud.unikraft.v1.instances/scale_to_zero.stateful: "false"
+  cloud.unikraft.v1.instances/scale_to_zero.cooldown_time_ms: 1000
+
+rootfs: ./Dockerfile
+
+cmd: ["/opt/unikraft/dropbeard.sh"]
diff --git a/netutils/README.md b/netutils/README.md
new file mode 100644
index 00000000..91716ce4
--- /dev/null
+++ b/netutils/README.md
@@ -0,0 +1,37 @@
+# Netutils Example image
+
+This image contains a minimal user space environment based on Alpine Linux.
+A SSH server is launched and a couple of essential networking tools such as
+`nslookup`, `ping`, `traceroute`, `ip`, `socat`, and `tcpdump` are preloaded.
+
+To run this example on Unikraft Cloud, first [install the `kraft` CLI tool](https://unikraft.org/docs/cli).
+Then clone this examples repository and `cd` into this directory, and invoke:
+
+```console
+kraft cloud deploy
+```
+
+Alternatively, you can deploy the image accepting your public key by handing it over the `PUBKEY`
+environment variable, for example:
+
+```console
+kraft cloud deploy  -e PUBKEY="$( cat $HOME/.ssh/id_rsa.pub )"
+```
+
+After deploying, you can connect to the console via SSH through a tunnel.
+Run the command below:
+
+```console
+kraft cloud tunnel 2222:<instance-name>:22
+```
+
+Then connect to the instance via SSH using (default password is `unikraft`):
+
+```console
+ssh root@localhost -p 2222
+```
+
+## Learn more
+
+- [Unikraft Cloud's Documentation](https://unikraft.cloud/docs/)
+- [Building `Dockerfile` Images with `Buildkit`](https://unikraft.org/guides/building-dockerfile-images-with-buildkit)
diff --git a/netutils/dropbeard.sh b/netutils/dropbeard.sh
new file mode 100755
index 00000000..c4e2f76c
--- /dev/null
+++ b/netutils/dropbeard.sh
@@ -0,0 +1,18 @@
+#!/bin/sh -e
+export HOME=/root
+
+mkdir -p "${HOME}"
+chmod 700 "${HOME}"
+cd "${HOME}"
+
+# Install public key if given by user
+if test -n "${PUBKEY}"; then
+	mkdir -p  "${HOME}/.ssh"
+	chmod 700 "${HOME}/.ssh"
+	echo "${PUBKEY}" >> "${HOME}/.ssh/authorized_keys"
+	chmod 600 "${HOME}/.ssh/authorized_keys"
+	unset PUBKEY
+fi
+
+# Launch dropbear SSH server
+exec /usr/sbin/dropbear -ERF
diff --git a/netutils/motd b/netutils/motd
new file mode 100644
index 00000000..158ef1d5
--- /dev/null
+++ b/netutils/motd
@@ -0,0 +1,20 @@
+ _   :=:
+| |:=:
+| |__:=: UNIKRAFT
+ \_____/ CLOUD
+
+Welcome to Unikraft Cloud!
+
+This is the netutils example image, its user space
+is built on Alpine Linux: <https://wiki.alpinelinux.org/>.
+For details about this image, visit:
+<https://github.com/unikraft-cloud/examples/netutils>.
+
+This image comes preloaded with essential networking
+tools such as nslookup, ping, traceroute, ip, socat,
+and tcpdump. Need more? Just install additional
+packages using apk. But keep an eye on your free
+RAM.
+
+Enjoy!
+
diff --git a/netutils/profile b/netutils/profile
new file mode 100644
index 00000000..3d3caa31
--- /dev/null
+++ b/netutils/profile
@@ -0,0 +1 @@
+PS1='# '