Is it possible to remotely force a reboot on Ubuntu 20.04.3?

[Robert Heller]

At Mon, 21 Feb 2022 19:40:48 +0100 bo.berglund at gmail.com, "Ubuntu user technical support,? not for general discussions" <ubuntu-users at lists.ubuntu.com> wrote:

> 
> On Mon, 21 Feb 2022 11:22:46 -0500 (EST), Robert Heller <heller at deepsoft.com>
> wrote:
> 
> >At Mon, 21 Feb 2022 16:08:20 +0100 bo.berglund at gmail.com, "Ubuntu user technical support,? not for general discussions" <ubuntu-users at lists.ubuntu.com> wrote:
> >
> >> 
> >> On Mon, 21 Feb 2022 15:44:21 +0100, Bo Berglund <bo.berglund at gmail.com> wrote:
> >> 
> >> >So it seems like it is in real need of a restart...
> >> >
> >> >But is it possible to force such when the situation is as described?
> >> >
> >> 
> >> I have tried this from
> >> https://www.cyberciti.biz/faq/remote-shutdown-linux-computer-from-the-cli/
> >> 
> >> $ ssh -t bosse at aspomint 'sudo reboot'
> >> ssh_exchange_identification: Connection closed by remote host
> >> 
> >> So even this fails...
> >
> >Try:
> >
> >telnet aspomint 22
> 
> $ telnet aspomint 22
> Trying 192.168.117.251...
> Connected to aspomint.
> Escape character is '^]'.
> Connection closed by foreign host.
> 
> >
> >(you might have to do an 'apt install telnet' to get the telnet command)
> >
> >This will test to see if the machine is listening on port 22 -- if not, sshd 
> >crashed, *BUT* if it is listening on port 22, then
> >
> >slogin -v bosse at aspomint
> 
> $ slogin -v bosse at aspomint
> OpenSSH_7.9p1 Raspbian-10+deb10u2+rpt1, OpenSSL 1.1.1d  10 Sep 2019
> debug1: Reading configuration data /etc/ssh/ssh_config
> debug1: /etc/ssh/ssh_config line 19: Applying options for *
> debug1: Connecting to aspomint [192.168.117.251] port 22.
> debug1: Connection established.
> debug1: identity file /home/pi/.ssh/id_rsa type -1
> debug1: identity file /home/pi/.ssh/id_rsa-cert type -1
> debug1: identity file /home/pi/.ssh/id_dsa type -1
> debug1: identity file /home/pi/.ssh/id_dsa-cert type -1
> debug1: identity file /home/pi/.ssh/id_ecdsa type -1
> debug1: identity file /home/pi/.ssh/id_ecdsa-cert type -1
> debug1: identity file /home/pi/.ssh/id_ed25519 type -1
> debug1: identity file /home/pi/.ssh/id_ed25519-cert type -1
> debug1: identity file /home/pi/.ssh/id_xmss type -1
> debug1: identity file /home/pi/.ssh/id_xmss-cert type -1
> debug1: Local version string SSH-2.0-OpenSSH_7.9p1 Raspbian-10+deb10u2+rpt1
> ssh_exchange_identification: Connection closed by remote host

This isn't the Ubuntu machine.  It is a Raspberry Pi.  And for some reason it 
is mapping the bosse user to the pi user...

> 
> 
> >Should give you an idea as to why ssh is not working.
> >
> >Possiblities include a disk problem (/home is in trouble) or sshd is 
> >overloaded (ddos attack) or fail2ban has been triggered for your IP.
> 
> I seriously doubt a ddos attack. The ASUS router is connecting by VPN to my home
> LAN and it is set up to be bidirectional. I can reach everything else on the
> remote LAN from home including pinging the Ubuntu machine, but whatever else I
> do results in an immediate disconnect as seen above.
> 
> >Question: does root itself have a legit password (by default Ubuntu disables 
> >loging in as root directly, by giving root an "invalid" password)?  If root 
> >has a valid passord (or you have placed a SSH public key in 
> >~root/.ssh/authorized_keys), then you can try:
> 
> I have not done anything about root. The system is in that respect as installed
> from the ISO.
> 
> 
> 

-- 
Robert Heller             -- Cell: 413-658-7953 GV: 978-633-5364
Deepwoods Software        -- Custom Software Services
http://www.deepsoft.com/  -- Linux Administration Services
heller at deepsoft.com       -- Webhosting Services