A jump script for the mobile shell (Mosh) when used to connect to Proxmox containers/VMs via its root PVE node

proxmosh.sh

#!/usr/bin/env bash

# The public IP address or the Dynamic DNS hostname of the 
# proxmox host, which can be resolved to a public IP address 
PROXMOX_HOST=host.dyndns.org
# A single TCP port that is used for initiating a connection
PROXMOX_TCP_PORT=2222
# A range of UDP ports that can be used for each Mosh session
PROXMOX_UDP_PORTS=60001:60008

PROXMOSH_BIN=/root/.local/bin
PROXMOSH_LOG=$PROXMOSH_BIN/proxmosh.log

# This is a new feature I added considering how painful are
# the qm and the pct commands to use. Instead, now you have
# the choice of configuring SSH so that it can be used instead
# to access the container/VM from the root PVE node.
USE_SSH_WHEN_POSSILE=1

declare -A container=(
    [singular]='LXC container'
    [plural]='LXC containers'
    [base_command]='pct'
    [list_subcommand]='list'
    [jump_subcommand]='console' 
)

declare -A vm=(
    [singular]='VM'
    [plural]='VMs'
    [base_command]='qm'
    [list_subcommand]='list'
    [jump_subcommand]='terminal' 
)

technologies=(container vm)

find_target() {
    # the first argument contains the name of the VM or the container
    if [[ -z "$1" ]]; then return 1; fi
    
    local return_code
    local output
    
    for ref in "${technologies[@]}"; do
        declare -n tech="$ref"

        output=$("${tech[base_command]}" \
            "${tech[list_subcommand]}" | awk -v name="$1" '
        function get_field(field_name) {
            temp = substr($0, col_pos[field_name])
            match(temp, /\S+/)
            value = substr(temp, RSTART, RLENGTH)
            return value
        }
        NR == 1 {
            for (i = 1; i <= NF; i++) {
                col_pos[tolower($i)] = index($0, $i)
            }
            exit_code = -1
            next
        }
        get_field("name") == name {
            vmid   = get_field("vmid")
            status = get_field("status")
            if (status != "running") {
                print "Error: '"${tech[singular]}"' " name " is " status > "/dev/stderr"
                exit_code = 1
            } else {
                print vmid
                exit_code = 0
            }
        }
        END { 
            if (exit_code == -1) {
                exit_code = 2;
            }
            exit exit_code
        }')

        return_code=$?

        if [[ $return_code -eq 0 ]]; then 
            declare -gir TARGET_ID="$output";
            declare -gr  TARGET_TECH="$ref";
        fi

        if [[ $return_code -ne 2 ]]; then
            break
        fi
    done

    if [[ $return_code -eq 2 ]]; then
        local plural_terms=()
        for ref in "${technologies[@]}"; do
            declare -n tech="$ref"
            plural_terms+=("${tech[plural]}")
        done 
        
        local IFS='/'
        echo "Error: no ${plural_terms[*]} were found using the name '$1'." >&2
    fi

    return $return_code
}

running_in_proxmox=1

for ref in "${technologies[@]}"; do
    declare -n tech="$ref"
    if ! command -v "${tech[base_command]}" &>/dev/null; then
        running_in_proxmox=
    fi
done 

if [[ -n "$running_in_proxmox" ]]; then
    target_invoked=

    if [[ -n "$1" ]]; then
        if [[ -n "$USE_SSH_WHEN_POSSILE" ]]; then
            ssh -T "$1" true &>/dev/null
            if [[ $? -eq 0 ]]; then
                target_invoked=1
                exec ssh "$1"
            fi
        fi

        if [[ -z "$target_invoked" ]] && find_target "$1"; then 
            mkdir -p "$PROXMOSH_BIN"
            declare -n tech="$TARGET_TECH"

            jump_command="${tech[base_command]} ${tech[jump_subcommand]}"
            echo "$(date): $jump_command '$TARGET_ID'" >> "$PROXMOSH_LOG"
            
            target_invoked=1
            $jump_command "$TARGET_ID"
        fi
    fi

    if [[ -z "$target_invoked" ]]; then
        exec /usr/bin/env bash -l
    fi
else 
    ssh -p $PROXMOX_TCP_PORT $PROXMOX_HOST "mkdir -p $PROXMOSH_BIN"
    ssh_command="ssh -p $PROXMOX_TCP_PORT"

    if command -v rsync &>/dev/null; then 
        rsync -az -e "$ssh_command" "$0" $PROXMOX_HOST:"$PROXMOX_BIN/proxmosh"
    elif command -v scp &>/dev/null; then 
        scp -P "$PROXMOX_TCP_PORT" "$0" $PROXMOX_HOST:"$PROXMOSH_BIN"
    else 
        echo "Error: script requires either 'rsync' or 'scp' to be installed." >&2
        exit 1
    fi

    if [[ $? -ne 0 ]]; then
        exit 1
    fi

    mosh --ssh="$ssh_command" -p "$PROXMOX_UDP_PORTS" $PROXMOX_HOST -- "$PROXMOSH_BIN/proxmosh" "${1:-}"
fi

Setup: Change the values of PROXMOX_HOST, PROXMOX_TCP_PORT, and PROXMOX_UDP_PORTS to match your setup.

Usage: proxmosh to connect via Mosh to the root node, and proxmosh name to connect to a container/VM with the name name. In case of preferring SSH, be sure to add the public PVE node SSH certificate to authorized_hosts on the container/VM and configure the user you wish to log in using in /root/.ssh/config on the root PVE node.

For more information, check the supporting tutorial at https://forum.proxmox.com/threads/use-mobile-shell-mosh-with-proxmox.173209/