Jakub's questions

I have a Debian Stretch VM that is dynamically migrated between a few hosts. I need to connect a serial (RS-232) modem to it. Unfortunately, I cannot use the hypervisor for this.

I am looking for a reliable method of mapping a serial port from one (physical) server to a VM (in a serial-over-ethernet manner), but there's a requirement that this must provide a virtual device file (like /dev/ttySX) on the VM. Additionally, it'd be highly desired if the whole setup could re-establish the connection after rebooting either of the servers, without requiring manual intervention.

I have a couple of devices with web-based interfaces that I need to regularly check status of.

A server is considered working (healthy) when it is returning 1xx (continue), 2xx (success) or 3xx (redirect) http status code. It is considered dead when it returns 4xx (client error) or 5xx (server error) codes or when it doesn't respond in a given time.

As for obtaining the status code - I have this covered:

curl -I http://server.domain

How to reliably detect timeout (let's say I consider 5 seconds to be too much, it's plenty of time since this is happening in a LAN with little to no traffic) and kill the curl process if the given time passes and there is no response? Or better yet - how to connect them to have a single script that returns TRUE if the server is healthy, and FALSE if the server returns errors or times out?

I own a small home NAS/Server - Zyxel NSA310S. Unfortunately, in the official package repository, only the 5.0.8 version is available. Last year I managed to install the 7.x. version, using the method below:

    (Connect to the NSA as root using telnet - you first need to enable 
    in the administrator's webpanel. Then you can run the commands.)
cd /usr/local/zy-pkgs/gui
wget http://download.owncloud.org/community/owncloud-latest.tar.bz2
tar xjvf owncloud-latest.tar.bz2
cp ownCloud/config/config.php owncloud/config/config.php
vi owncloud/config/config.php
    (To set 'version' to the correct value for the downloaded one.)
cd /usr/local/zy-pkgs/gui/owncloud/lib/private
chmod 660 config.php
cd /usr/local/zy-pkgs/gui
mv ownCloud oldCloud
    (Just to be safe, keeping the old original version at hand for now.)
mv owncloud ownCloud
    (Putting the new version in place of the old one. Now only thing needed 
    is to log in as the admin to the web interface and follow the instruction
    shown on screen - voila, new version installed and working.)

Unfortunately, this method does not work at all with the current version of ownCloud. I don't know what has been changed that broke this method of upgrade, nor which version was the last one to work.

Has anyone experimented with ZyXEL NSA's? Or has any idea which version of the ownCloud might work with this device?

I use the newest version of the firmware - 4.75.