rstash − system for write-only remote file copying The system is a protocol and a pair of programs for transmitting data from one host to another without the need to open shell accounts, network file systems, or full-fledged file transfer protocols. It is useful for transferring backups from a host to a central backup server, for one thing. is based on the concept of "boxes". The server (running provides various boxes into which files can be stashed. The client transmits data to be stored in a particular box with a given name to the server using Names are (restricted) file names, but cannot specify paths; therefore, the client is prohibited by the protocol from writing data to arbitrary locations.

The client can only write data to the server; it cannot read data, list boxes, or list files. It also cannot overwrite data; if a the box already contains a file using the name provided by the client, the write is denied.

provides some light authentication in the form of a challenge-response scheme based on CRAM using the SHA-1 hash. Each box has an authentication key, and file transfers into this box must authenticate with the proper key. While does provide some authentication capabilities, it is recommended that hosts also use firewalls, and other appropriate host-based authentication mechanisms to protect the server process. It is intended, however, that the worst thing an attacker can do is fill disk and take names needed by backup processes (which could be construed as a DoS attack). The strength of the authentication mechanism is unknown. A stronger mechanism (probably based on cryptographic signatures such as DSA) should be developed.

Other bugs may be present and should be reported to the author. Copyright (c) 2008 Michael Ekstrand

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