1. Chapter 19 FTP: Transferring Files Across a Network
FTP Client
JumpStart: Downloading Files Using fip Notes
Anonymous FTP
Automatic Login
Binary versus ASCII Transfer Mode
ftp Specifics
FTP Server (vsftpd)
JumpStart: Starting a vsftpd Server
Testing the Setup
vsftpd.conf: Configuring vsftpd
Dumb versus terminal emulation
Palette computers
Wyse terminals
blue screen terminals
dial-in
telnet
Passwords selection - currently ssn
Commands
date
Fri Aug 29 10:00:12 MST 1997
who
resparza tty12 Aug29 10:00
johnson
johnson: not found
cal
finger
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2. Introduction
ftp has been around as one of the original TCP/IP protocols
ftp and vsftpd – this chapter will focus more on vsftpd since it is provided with Fedora
Security – vsftp is secure, ftp is not
Connections – passive is client initiated connection, active is if server initiates
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3. FTP Client ftp – command line, Linux or Windows
sftp – secure ftp, part of OpenSSH
gftp – graphical ftp, supports ftp, SSH, and HTTP
ncftp – Fedora text-based utility with more features than standard ftp
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4. Standard ftp screen
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5. gFTP
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6. NcFTP
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7. ]umpStart: Downloading Files Using ftp
Basic commands:
ftp ftp.server.net
ftp> open ftp.server.net
ftp> user
ftp> get (mget)
ftp> put (mput)
ftp> prompt
ftp> hash
ftp> ascii or binary
ftp> cd and lcd
ftp> quit or bye
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8. Anonymous FTP Can use user id of either
anonymous or
ftp (some systems)
Enter address as password if necessary, see automatic login below
ftp server can use reverse DNS to verify
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9. Automatic Login
Place ~/.netrc file in your home directory to allow automatic login:
$ cat .netrc
machine bravo login jimbo password xyz123
Make readable only by owner!
Can defeat at ftp server config file
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10. Binary versus ASCII Transfer Mode
Binary mode (default for some systems) provides a byte by byte exact transfer
ASCII (ascii) mode converts end of line characters between Windows and Unix systems
Can also use dos2unix or unix2dos
Security – always use binary mode
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11. ftp Specifics Format – ftp [-options] server Options: -i interactive
-g globbing, file name expansion with wild cards
-v verbose
-n no automatic login with .netrc
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12. ftp commands Shell command = !command (!ls) Transfer files:
append local remote
get remote-file [new local file name]
mget remote-file-list [wild cards allowed]
put local-file [new remote file name]
mput remote-file-list [wild cards allowed]
newer remote-file [new local file name]
reget remote-file [new local file name]
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13. status ascii – sets transfer mode to ASCII
binary – sets transfer mode to binary
close – quits ftp server without leaving ftp
open [server name] – opens new ftp connection
hash – shows hash marks (#) during transfers
prompt – toggles prompts for transfers
passive – toggles between passive and active
user – sign in as different user
quit or bye – exits ftp site and closes ftp
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14. Directories cd - changes directories on ftp server/site
lcd – changes local directories on your machine
Do not use ftp> ! cd newdirectory
Remember that the environment does not change in a spawned process!
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15. Files chmod – to change permissions on files
delete – to delete remote file(s) if allowed
mdelete remote-file-list
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16. Display Information dir – like ls but has file option:
dir [remote-dir] file
(file saved on your local system with contents of the remote directory listing)
ls – same as dir but with more information
help – shows commands
pwd – print working remote directory
status – status information
verbose – to see all that is happening
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17. FTP Server (vsftpd)
The vsftpd package is installed by default on Red Hat systems
Modes:
Standalone – set listen parameter to “yes” in vsftpd.conf file
Normal – use xinetd superserver to start and stop, set to normal by default
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18. JumpStart: Starting a vsftpd Server
Make sure service is running:
# /sbin/service vsftpd status
vsftpd (pid 3022) is running . . .
Check permissions in /var/ftp directory
# ls –ld /var/ftp
drwxr-xr-x 4 root root 4096 Aug 12 /var/ftp
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19. vsftpd connection from localhost
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20. vsftpd connection from remote host
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21. vsftpd.conf: Configuring vsftpd
Standalone – listen=yes
listen_port (default 21)
listen_address – defaults to any network interface
max_clients – set to 0 for unlimited
max_per_ip – set to 0 for any IP address allowed
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22. Logging in
userlist_enable – yes further checks userlist_deny, no does not check the list, more secure is no
userlist_deny – list of users denied access
userlist_file – name of user list file
local_enable – allows users in /etc/passwd file to log onto system
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23. Anonymous Users anonymous_enable – yes allows anonymous
no_anon_password – yes won’t ask for password
deny_ _enable – yes checks if password
user is denied access to system
banned_ _file – list of denied users by
address
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24. Working Directories and chroot jail
chroot_list_enable – sets user in jail either in their home directory or in /var/ftp
chroot_local_user – if set to no local user can move around directory structure
chroot_list_file – naem of the file if chroot_list_file is set to yes
passwd_chroot_enable – allows local user to cd to home directory (/home/./jones)
secure_chroot_dir – empty directory that is not writeable by user ftp, a secure chroot jail
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25. Messages dirmessage_enable – yes displays .message
banner_file – file that is displayed at login, overrides ftpd_banner
ftpd_banner – overrides the standard vsftpd greeting banner at connection time
And speaking of banners:
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26. Any Questions?
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