1 COP 4343 Unix System Administration Unit 15: file server – ftp – nfs

2 File server Remote access to files ftp –put/get files from remote hosts nfs –tight integration in Unix environment samba –share access to/from Windows systems

3 File Transfer Protocol designed for efficient distribution of a single file to multiple remote clients design characteristics –operates in real-time –to be used by general public anonymously userid: ftp –very effective for transferring large files –not designed as a “shared local disk”

4 FTP clients Command line: –ftp, lftp, sftp, ncftp GUI-based: –gftp web browsers via URL –ftp://mirror.cs.fiu.eduftp://mirror.cs.fiu.edu

5 FTP server vsftpd “Probably the most secure and fastest FTP server for UNIX-like systems” vsftpd.beasts.org to install on Fedora: –yum install vsftpd

6 vsFTPd server configuration: /etc/vsftpd/vsftpd.conf anonymous_enable=YES local_enable=YES write_enable=YES listen=YES tcp_wrappers=YES check run level & start daemon: –chkconfig vsftpd on –service vsftpd start

7 vsFTPd server security open firewall to ports –20: ftp data –21: ftp control enable ftp connection tracking –add module: ip_conntrack_ftp –to: /etc/sysconfig/iptables-config list of non-allowed users: –/etc/vsftpd.ftpusers

8 Network File Systems NFS makes remote files part of the local directory structure –designed for permanent, long-term connections where remote file systems are used as part of the regular user environment –designed with a trusted network in mind –UNIX-centric and does not typically perform well with Windows servers

9 NFS client mount command: mount blitz:/disk/137/ege /mnt –mount point must exist –remote host must export directory

10 NFS client, mount options hard –if remote access fails, request will hang until server resumes –option: intr allows hanging process to be killed soft –if remote access, error will be reported

11 NFS client, mount options permission ro: read-only rw: read and write nosuid: disable setuid behavior more options available for server

12 NFS client automatic mounting at system startup /etc/fstab: blitz:/disk/137/ege /mnt/ege nfs rw,hard,intr 0 0

13 NFS server NFS uses RPC –similar to xinetd : uses RPC number –portmap listens for rpc requests, then maps them to TCP or UDP ports –NFS uses the rpc.mountd daemon to make new connections check services in run level: –portmap –nfs

14 NFS server: export configuration: /etc/exports ex: /home blitz(rw) /home *.cs.fiu.edu(ro,root_squash) options: –rw, ro –root_squash –all_squash –anonuid

15 NFS server: firewall problem: RPC mechanism uses random ports solution: –open firewall to trusted machines rule option: -s /32