NFS: Network File Sharing Service (Server)

NFS (Network File System) is a protocol used for file sharing within UNIX environments. Windows users typically cannot access these shared files, as NFS is specifically designed for UNIX systems.

Key Information

• Package Name: nfs-utils
• Service Name: nfs
• Port Information: NFS does not have a specific port; it relies on the portmapper service, which operates on port 111. To check the status of the portmapper service, use:

service portmap status
netstat -atnp | grep 111

Configuration Path: /etc/exports Log File: /var/log/messages

Sharing Files and Directories

To share a file or directory, you need to specify its path in the /etc/exports file using the following format:

sharename ID/IP permissions Configuration Examples:

• Read-Only with Sync: /crackers *(ro,sync) This shares the /crackers directory with read-only access and ensures that new files are visible only after they are fully copied.
• Read-Write with Async: /crackers *(rw,async) This shares the /crackers directory with read-write access, allowing users to see new files before they are fully copied.
• Read-Write for a Specific Subnet: /crackers 192.168.0.0/255.255.255.0(rw,sync) This grants read-write access to all IPs within the specified subnet.
• Domain-Based Access: /crackers *.blackhats.com(rw,sync) This shares the /crackers directory with all users from the blackhats.com domain with read-write permissions.
• Mixed Permissions: /crackers *.blackhats.com(ro,sync) EXCEPT godfather.blackhats.com(rw,async) This grants read-only access to all users from the blackhats.com domain, while godfather.blackhats.com has read-write access with async visibility.

Accessing NFS Shares

To access network shares, you must mount them using the following command:

mount /source:/path@server /Destination For example:

mount /192.168.0.1:/crackers /mnt/nfsshares Whenever you create a new mount point, restart the NFS service. However, during file replication, avoid restarting the NFS service. Instead, use the following commands to update:

exportfs -ra # Updates NFS exports exportfs -v # Displays current mounts It’s crucial that the root user sets appropriate permissions on these shares to allow user access.

NFS also facilitates installations within UNIX environments, making it a versatile tool for network file management.