---
name: "sfscd"
section: "8"
platform: "linux"
package: "sfs-client"
version: "1:0.5k-8"
release: "Debian 3.0 (Woody)"
platforms: ["linux"]
url: "https://new.carta.tech/sfs"
---

# sfscd(8)

Self Certifying Filesystem

Part of [sfs(7)](/sfs/7.md).

## NAME

SFS - Self Certifying Filesystem

## DOCUMENTATION

This manpage was written as short description and as pointer to  more complete documentation. Up to date documentation can be  found as Info-pages of SFS or from /usr/share/doc/sfs-common  in Debian systems. You can access the Info pages with command "info sfs".

## DESCRIPTION

SFS is a secure, global network filesystem with comple- tedly decentralized control. It takes NFS shares expor- ted from localhost and transports them securely to other  hosts; NFS services do not need to be exposed to network.

SFS features key management and authorization separated from  filesystem with key revokation separated from key distribution.

More information and new versions can be found from:

http://www.fs.net

## GLOBAL NAMESPACE

SFS mounts directories from fileservers under a directory in the form:

/sfs/**Location**:*HostID*

**Location** is either ip address or hostname of the server.

*HostID* is a collision-resistant cryptographic hash of  Location and the file server's public key.

## CLIENT DESCRIPTION

Client side operation of SFS consists of following prog- rams:\

- **sfscd**

  creates and serves /sfs directory on client machine. Also starts nfsmounter and sfsrwcd as needed. \

- **nfsmounter**

  mounts and unmounts NFS filesystems as kernel NFS client accesses them.\

- **sfsrwcd**

  is a daemon that implements normal read/write filesystem protocol. It acts as a NFS server to local NFS client.

## USER PROGRAMS

On client machine user normally uses the following prog- rams:\

- **sfsagent**

  handles authentication as user moves to new filesystems. It also can fetch new HostIDs and perform revocation checks on them.\

- **sfskey**

  manages user and server keys and is used to configure sfsagent for different situations.

## SERVER DESCRIPTION

Server side consists of following programs:\

- **sfssd**

  handles incoming connections and spawns sfsrwcd and sfsrwcd as needed.\

- **sfsrwcd**

  is a daemon that implements normal read/write filesystem protocol and  talks to local NFS server.\

- **sfsauthd**

  handles user authentication. It communicates directly with sfsrwsd  to authenticate users of the file system. It also accepts connections  over the network from sfskey to let users download their private keys  or change their public keys.

## HELPER BINARIES

There are few small programs to help with misc tasks:\

- **rpcc**

  To be documented.\

- **funmount**

  To be documented.\

- **dirsearch**

  can be used with **sfskey certprog** command to configure certification paths --lists of directories in which to look for symbolic links to *HostID*s.

Usage is:\

- **dirsearch** \[**-clpq**\] dir1 \[dir2 ...\] name

  **dirsearch** searches through dir1-x untill it finds the file "name" and prints "dir/name". Following options affect this:\

- **-c**

  Print the contents of the file to standard output, instead of its pathname. \

- **-l**

  Require that "dir/name" be a symbolic link, and print the path of the link's destination, rather than the path of the link itself. \

- **-p**

  Print the path "dir/name". This is the default behavior anyway, so the option **-p** has no effect.\

- **-q**

  Do not print anything. Exit abnormally if "name" is not found in any of the directories.\

- **ssu**

  The **ssu** command allows an unprivileged user to become root on the local machine without changing his SFS credentials. **ssu** invokes the command **su** to become root. Thus, the access and password checks needed to become root are identical to those of the local operating system's **su** command. **ssu** also runs /usr/lib/sfs-0.5/newaid to alter the group list so that SFS can recognize the root shell as belonging to the original user.

  Usage:\

- **ssu** \[**-f** \| **-m** \| **-l** \| **-c** command\]

  - **-f**

  - **-m**

  this and **-f** command are passed through to the **su** command.\

- **-l**

  This option causes the newly spawned root shell to behave like a login shell.\

- **-c** command

  Tells ssu to tell su to run command rather than running a shell.

## SEE ALSO

[sfskey(1)](/sfskey/1.md), [nfs(5)](/nfs/5.md), [info(1)](/info/1.md), [sfsagent(1)](/sfsagent/1.md)

## NOTES

Solid NFSv3 support is required from kernel and supporting utilities.

## CAVEATS

You really do not want to kill nfsmounter, as it is responsible for cleaning up and unmounting filesystems on the client side, if sfscd has died or something else happened.

## BUGS

/sfs is not FHS compliant. FHS on the other hand is lack- ing mount points for system mounts.

## AUTHOR

This manpage was written by Jaakko Niemi for sfs packaging in  Debian/GNU Operating System.