Setup a webserver on the Pi that returns "This is the Pi of iam_agf". Or even a dynamic page that returns the IP, something like "192.168.0.15 iam_agf". This is to make sure that it is your device and not he printer or coffee machine.

You can use nmap to see which IPs have a webserver running, and then check those to see if the contain your keyword and the IP.

Once you get back an IP, place it in your /etc/hosts file, so you can easily access the pi by name.

Simple check if it works without nmap, might take some time:

for i in $(seq 1 254); do
    curl "http://192.168.0.${i}" | grep iam_igf
done

Setup a webserver on the Pi that returns "This is the Pi of iam_agf". Or even a dynamic page that returns the IP, something like "192.168.0.15 iam_agf". This is to make sure that it is your device and not he printer or coffee machine.

You can use nmap to see which IPs have a webserver running, and then check those to see if the contain your keyword and the IP.

Once you get back an IP, place it in your /etc/hosts file, so you can easily access the pi by name.

Simple check if it works without nmap, might take some time:

for i in $(seq 1 254); do
    curl "http://192.168.0.${i}" | grep iam_igf
done

There's a plugin for nmap called ssh-brute, you can try this with one fixed username and password combination. https://nmap.org/nsedoc/scripts/ssh-brute.html

Also what you were probably looking for initially:

#this will open an ssh connection and wait for you to type stuff:
ssh user@IP

#this will run a command after the connection is open, then close it
ssh user@IP command

# example
ssh user@IP echo ok

# or just use the true command to avoid output
ssh user@IP true

# so this loop might do what you need, (untested, make backups of /etc/hosts first!)
for i in $(seq 1 254); do
    if ssh "[email protected].${i}" true;
    then
        sed -i "/[0-9.]* mypi/d" /etc/hosts
        echo "192.168.0.${i} mypi" >> /etc/hosts
        break
    fi
done

May