Source URL: https://utcc.utoronto.ca/~cks/space/blog/sysadmin/RsyncForLimitedRemoteWrite
Source: Hacker News
Title: Using rsync to create a limited ability to write remote files
Feedly Summary: Comments
AI Summary and Description: Yes
Summary: The text outlines a method for securely backing up data between two sensitive machines, emphasizing a limited trust model. It employs rsync’s daemon mode over SSH for data transfer, detailing configuration settings that enhance security and ensure only necessary permissions are granted.
Detailed Description:
The text presents a practical solution for backing up data between a high-security source machine and a backup machine that also has sensitive data, while limiting trust between the two. This scenario is becoming increasingly relevant in environments where data security and compliance are critical. Key points include:
– **Isolation and Trust Management**:
– Emphasizes the need for an isolated environment where machines do not fully trust each other.
– Suggests pushing data instead of pulling it to mitigate risks.
– **Implementation Using rsync and SSH**:
– Recommends using rsync in daemon mode on the backup host combined with SSH for secure data authentication and encryption.
– Points out that rsync’s daemon mode allows for granular control of access via configuration files (rsyncd.conf).
– **Configuration Details**:
– Example rsyncd.conf settings provide insight into restricting directory permissions, limiting allowed hosts, and using chroot to enhance security.
– Discusses the necessity of a shell script to enforce rsync’s daemon operation with specific configurations.
– **Secure SSH Key Management**:
– Outlines the requirement for creating a secure SSH key pair and configuring the .ssh/authorized_keys file to restrict what can be executed on the backup machine.
– Highlights the importance of configuring SSH commands to prevent potential misuse by the source machine.
– **Backup Operations and Flexibility**:
– Provides options for configuring rsync behavior, such as setting it to writing only, which prevents the high-security machine from retrieving files unnecessarily.
– Mentions that this setup is easy to implement, particularly if a similar setup exists for read-only replication.
This approach is of substantial interest to security professionals, as it not only addresses practical backup needs but also incorporates essential security principles such as minimal trust, controlled access, and encrypted data transfer. Such configurations can be critical for compliance with security policies and regulations, making it a valuable reference for those looking to implement best practices in their data management strategies.