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SFTP integration package

Introduction

Requirements

  • Plakar version: “1.0.2 or >=1.0.3”
  • Integration version: “0.1.0”
  • SFTP/SSH server accessible with read/write permissions

This integration enables backing up, restoring, and storing remote directories using Plakar’s built-in SFTP connector over SSH. SFTP is supported natively, requiring only that the target system has SSH and SFTP access enabled.

Snapshots are stored in a Kloset store with full deduplication, encryption, and immutability, whether hosted locally or on an SFTP-accessible remote server. All data transfers are encrypted end-to-end, and Plakar automatically verifies each snapshot to ensure data integrity.

Use cases:

  • Secure, encrypted backups of remote Linux, BSD, or application servers
  • Hosting Kloset stores on remote SFTP servers for offsite or air‑gapped backup
  • Disaster recovery and rapid restoration of server directories over SSH
  • Automated compliance backups of sensitive or regulated data
  • Centralized archiving of distributed infrastructure into a single Plakar Kloset

Target technologies:

  • Supported versions: Any system with OpenSSH 7.0+ or equivalent SFTP implementation
    • System compatibility: Compatible with on-premise, cloud-hosted, or hybrid Linux servers.
  • Unsupported variants:
    • Legacy SSH servers below 7.0
    • Proprietary or vendor-specific SFTP implementations that do not follow standard SSH protocol

Architecture

Components provided:

  • Source Connector: Extracts files and directories from remote servers over SFTP for secure, verifiable backups into a Kloset store.
  • Destination Connector: Restores Plakar snapshots to the original SFTP server or any compatible SSH-accessible resource.
  • Storage Connector: Supports hosting Kloset stores on SFTP servers, enabling offsite, encrypted, and air‑gapped snapshot storage.
  • Viewer: Accessible via the Plakar CLI or UI, allowing users to browse, search, and verify snapshots stored on SFTP-hosted Kloset stores.

Installation

This integration is bundled natively with Plakar. No additional package installation is required.

Verify SFTP Support:

1plakar/v1.0.2
2
3importers: fs, ftp, s3, sftp # <--- SFTP LISTED
4exporters: fs, ftp, s3, sftp # <--- SFTP LISTED
5klosets: fs, http, https, ptar, s3, sftp, sqlite # <--- SFTP LISTED

Check that SFTP is listed in your available connectors by running the command plakar version.

You should see sftp listed under importers, exporters, and klosets, for example:

This verifies integration is now ready for use.

Configuration

No special installation is required to use SFTP with Plakar.

Using direct SFTP URLs

1# Create a Kloset store on the local SFTP server
2plakar at sftp://sftpuser@localhost/uploads create
3
4# Backup data into the SFTP store
5plakar at sftp://sftpuser@localhost/uploads backup /home/<user>/Documents

Direct URLs are the simplest way to use SFTP with Plakar:

Direct URLs are fully self‑contained and require no prior configuration, ideal for ad‑hoc or one‑off operations.

Configure a named remote

1plakar config remote create mysftp
2
3# Point 'mysftp' to your SFTP server via an SSH host alias
4plakar config remote set mysftp location sftp://local-sftp/uploads

Named remotes let you simplify and reuse SFTP URLs in Plakar commands without typing the full connection string each time. This allows using sftp://local-sftp instead of the full sftp://sftpuser@localhost.

Configure an SSH host alias

(required) create an SSH host alias

1Host local-sftp
2    HostName localhost # <--- Creates the alias used in the Plakar URL
3    User sftpuser # <--- Specifies the SFTP account
4    IdentityFile ~/.ssh/id_ed25519_plakar # <--- Enables passwordless SSH for reliable backups

Test the alias

1# If it logs in without a password, the alias works
2sftp local-sftp

Since local-sftp is not a real hostname, you must define it in your ~/.ssh/config:

Ensure passwordless SSH access

1#  Must connect without a password for Plakar.
2ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519_plakar
3sftp -i ~/.ssh/id_ed25519_plakar sftpuser@localhost

Plakar relies on unattended SSH sessions for SFTP operations. To avoid interruptions or failed backups, configure passwordless login with an SSH key:

Test passwordless login with

sftp -i ~/.ssh/id_ed25519_plakar sftpuser@localhost

The command should log in directly without prompting for a password, this verifies that Plakar can reliably perform backups and restores over SFTP.

5. Setup backup model with SFTP Integration

6. Integration-specific behaviors

6.1 Limitations

The following are not included in SFTP snapshot backups:

  • System-wide configuration (e.g., SSH server settings, firewall rules)
  • User accounts and permissions on the remote host
  • Active processes or running services
  • Monitoring or telemetry configurations
  • Any server-side scripts or binaries outside the backed-up directories

Only the following are backed up:

  • Files and directories accessible via the configured SFTP path
  • File metadata such as timestamps, permissions, and sizes

6.2 Restore behavior specifics

Recommended best practices for restoring SFTP snapshots:

  • Always restore to a temporary or namespaced directory (e.g., sftp://myserver/restore-preview/) to avoid overwriting live data directly
  • Verify restored data integrity and completeness before promoting it to production paths
  • Use Plakar’s verification commands or checksum tools to validate snapshot correctness
  • Consider restoring snapshots to local filesystem first for inspection before pushing to remote servers

7. Troubleshooting

Credential / SSH errors If you see Permission denied or Connection refused:

  • Verify SSH key, username, and remote host configuration.

Host key issues Host key verification failed, Add the host to ~/.ssh/known_hosts or set insecure_ignore_host_key=true.

Permission denied on paths Ensure the SFTP user has read/write access to the source or destination directories.

8. Backup Strategy

  • Schedule daily or weekly snapshots with cron or timers.
  • Keep multiple snapshots for rollback and auditing.
  • Store backups on a separate SFTP store or local FS for safety.
  • Periodically verify snapshots with plakar ls or plakar verify.

9. Appendix

Plakar CLI Reference Plakar Architecture (Kloset Engine) OpenSSH / SFTP Documentation

Frequently Asked Questions

How do I configure username, port, or identity file? Use your SSH config (~/.ssh/config) to set HostName, User, Port, and IdentityFile for your SFTP host.

How can I avoid SSH passphrase prompts? Use an ssh-agent to cache your passphrase; Plakar will connect via $SSH_AUTH_SOCK if available.

Can I disable host key checks? Yes, set insecure_ignore_host_key=true on your remote.