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https://github.com/andreaso/ssh-zone-handler

Secondary DNS self-service
https://github.com/andreaso/ssh-zone-handler

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Secondary DNS self-service

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# SSH Zone Handler

* You run your own DNS server(s), providing Secondary DNS to others?
* You want to provide your DNS tenants with a bit of debugging self-service?
* You like SSH, but you don't want to grant people not-you full shell access?

If so, then this might just be the tool for you.

## Usage

Usage example, based on local [Vagrantfile][1] setup.

```
$ vagrant up
```

```
$ alias ssh="ssh -i .vagrant/machines/secondary/virtualbox/private_key"
```

```
$ ssh alice@192.168.63.11 help
usage: command [ZONE]

help Display this help message
list List available zones
dump ZONE Output full content of ZONE
logs ZONE1 [ZONE2] Output the last five days' log entries for ZONE(s)
retransfer ZONE Trigger a full (AXFR) retransfer of ZONE
status ZONE Show ZONE status
$
```

```
$ ssh alice@192.168.63.11 list
example.com
example.net
$
```

```
$ ssh alice@192.168.63.11 logs example.net
Apr 28 17:52:00 szh-secondary named[2821]: zone example.net/IN: Transfer started.
Apr 28 17:52:00 szh-secondary named[2821]: transfer of 'example.net/IN' from 192.168.63.10#53: connected using 192.168.63.10#53
Apr 28 17:52:00 szh-secondary named[2821]: zone example.net/IN: transferred serial 26281038
Apr 28 17:52:00 szh-secondary named[2821]: transfer of 'example.net/IN' from 192.168.63.10#53: Transfer status: success
Apr 28 17:52:00 szh-secondary named[2821]: transfer of 'example.net/IN' from 192.168.63.10#53: Transfer completed: 1 messages, 6 records, 190 bytes, 0.008 secs (23750 bytes/sec) (serial 26281038)
$
```

## Setup instructions

### Create log viewer user with journald access

```
adduser --system --no-create-home --home /nonexistent --shell /usr/sbin/nologin --ingroup systemd-journal log-viewer
```

### Create configuration

Create `/etc/zone-handler.yaml` based on either
[zone-handler.yaml.bind.example][2] or
[zone-handler.yaml.knot.example][3].

### Install application

```
python3 -m venv /opt/ssh-zone-handler
/opt/ssh-zone-handler/bin/pip3 install ssh-zone-handler
```

### Generate sudoers rules

```
/opt/ssh-zone-handler/bin/szh-sudoers | EDITOR="tee" visudo -f /etc/sudoers.d/zone-handler
```

### Configure sshd

```
Match User alice,bob
ForceCommand /opt/ssh-zone-handler/bin/szh-wrapper
PermitTTY no
AllowTcpForwarding no
X11Forwarding no
```

## Known limitations

* Might be Ubuntu distro specific

[1]: https://github.com/andreaso/ssh-zone-handler/blob/main/Vagrantfile
[2]: https://github.com/andreaso/ssh-zone-handler/blob/main/zone-handler.yaml.bind.example
[3]: https://github.com/andreaso/ssh-zone-handler/blob/main/zone-handler.yaml.knot.example