117 lines
3.2 KiB
Plaintext
117 lines
3.2 KiB
Plaintext
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#!/usr/bin/env bash
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# Copyright (c) 2025. LUXIM d.o.o., Slovenia - Matjaž Mozetič.
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# backtunnel-share: Share a folder using reverse SSH for a limited duration
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# Syntax: backtunnel-share /path/to/folder with remoteuser:remotehost for 2h
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# Options: -p|--tunnel-port <PORT> -l|--local-ssh-port <PORT> -h|--help
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set -euo pipefail
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TUNNEL_PORT=2222 # remote-side port exposed via -R
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LOCAL_SSH_PORT=22 # local sshd port to forward to
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DURATION="" # required: e.g. 30m, 2h, 1d
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usage() {
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cat >&2 <<EOF
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Usage:
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$(basename "$0") /path/to/folder with remoteuser:remotehost for <duration> [options]
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Positional (required, in order):
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/path/to/folder Informational only (the actual folder is mounted by backtunnel-access)
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with Literal keyword
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remoteuser:remotehost Or remoteuser@remotehost
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for Literal keyword
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<duration> e.g. 30m, 2h, 1d (passed to 'timeout')
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Options:
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-p, --tunnel-port N Remote tunnel port (default: ${TUNNEL_PORT})
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-l, --local-ssh-port N Local sshd port to expose (default: ${LOCAL_SSH_PORT})
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-h, --help Show this help
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Examples:
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$(basename "$0") ~/projects with alice:vps.example.com for 2h
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$(basename "$0") ~/projects with alice@vps.example.com for 1d -p 4422 -l 2222
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EOF
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exit 1
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}
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# --- basic positional parsing ---
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[[ $# -lt 5 ]] && usage
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FOLDER=$1
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KW1=$2
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REMOTE=$3
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KW2=$4
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DURATION=$5
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shift 5 || true
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[[ "$KW1" != "with" ]] && usage
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[[ "$KW2" != "for" ]] && usage
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# --- optional flags ---
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while [[ $# -gt 0 ]]; do
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case "$1" in
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-p|--tunnel-port)
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[[ $# -lt 2 ]] && usage
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TUNNEL_PORT=$2
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shift 2
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;;
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-l|--local-ssh-port)
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[[ $# -lt 2 ]] && usage
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LOCAL_SSH_PORT=$2
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shift 2
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;;
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-h|--help)
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usage
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;;
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*)
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echo "Unknown option: $1" >&2
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usage
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;;
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esac
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done
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# --- validate duration (timeout supports s,m,h,d) ---
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if [[ ! "$DURATION" =~ ^[0-9]+[smhd]$ ]]; then
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echo "Invalid duration '$DURATION' (use forms like 30m, 2h, 1d)." >&2
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exit 1
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fi
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# --- split remote user/host ---
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REMOTE_USER="" REMOTE_HOST=""
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if [[ "$REMOTE" == *:* ]]; then
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REMOTE_USER=${REMOTE%%:*}
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REMOTE_HOST=${REMOTE#*:}
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elif [[ "$REMOTE" == *"@"* ]]; then
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REMOTE_USER=${REMOTE%%@*}
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REMOTE_HOST=${REMOTE#*@}
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else
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echo "Invalid remote format. Use remoteuser:remotehost or remoteuser@remotehost" >&2
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exit 1
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fi
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# --- deps check ---
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command -v ssh >/dev/null 2>&1 || { echo "ssh not found."; exit 1; }
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command -v timeout >/dev/null 2>&1 || { echo "timeout not found."; exit 1; }
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echo "⏳ Sharing '${FOLDER}' via reverse SSH:"
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echo " local sshd port : ${LOCAL_SSH_PORT}"
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echo " remote bind port : ${TUNNEL_PORT} (on ${REMOTE_HOST})"
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echo " remote user : ${REMOTE_USER}"
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echo " duration : ${DURATION}"
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echo
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echo "Tip: On the remote side, mount with:"
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echo " backtunnel-access '${FOLDER}' from ${REMOTE_USER}@${REMOTE_HOST} -p ${TUNNEL_PORT}"
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timeout "$DURATION" ssh -N \
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-R "${TUNNEL_PORT}:localhost:${LOCAL_SSH_PORT}" \
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-- "${REMOTE_USER}@${REMOTE_HOST}"
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rc=$?
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if [[ $rc -eq 124 ]]; then
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echo "⏹️ Sharing ended: reached duration (${DURATION})."
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exit 0
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fi
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exit "$rc"
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