vsftpd-1.1.3配制实例之一：INTERNET_SITE

王朝other·作者佚名 2008-05-31

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This example shows how you might set up a (possibly large) internet facing

FTP site.

The emphasis will be on security and performance.

We will see how by integrating vsftpd with xinetd, we get a powerful

combination.

Step 1) Set up your xinetd configuration file.

An example xinetd configuration file "vsftpd.xinetd" is supplied.

To install it:

cp vsftpd.xinetd /etc/xinetd.d/vsftpd

Let's look at the important content in this file and see what it does:

disable = no

socket_type = stream

wait = no

This says that the service is active, and it is using standard TCP sockets.

user = root

server = /usr/local/sbin/vsftpd

The server program /usr/local/sbin/vsftpd is used to handle incoming FTP

requests, and the program is started as root (vsftpd will of course quickly

drop as mUCh privilege as possible). NOTE! Make sure that you have the vsftpd

binary installed in /usr/local/sbin (or change the file path in the xinetd

file).

per_source = 5

instances = 200

For security, the maximum allowed connections from a single IP address is 5.

The total maximum concurrent connections is 200.

no_Access = 192.168.1.3

As an example of how to ban certain sites from connecting, 192.168.1.3 will

be denied access.

banner_fail = /etc/vsftpd.busy_banner

This is the file to display to users if the connection is refused for whatever

reason (too many users, IP banned).

Example of how to populate it:

echo "421 Server busy, please try later." /etc/vsftpd.busy_banner

log_on_success += PID HOST DURATION

log_on_failure += HOST

This will log the IP address of all connection attempts - successful or not,

along with the time. If an FTP server is launched for the connection, it's

process ID and usage duration will be logged too. If you are using RedHat

like me, this log information will appear in /var/log/secure.

Step 2) Set up your vsftpd configuration file.

An example file is supplied. Install it like this:

cp vsftpd.conf /etc

Let's example the contents of the file:

# Access rights

anonymous_enable=YES

local_enable=NO

write_enable=NO

anon_upload_enable=NO

anon_mkdir_write_enable=NO

anon_other_write_enable=NO

This makes sure the FTP server is in anonymous-only mode and that all write

and upload permissions are disabled. Note that most of these settings are

the same as the default values anyway - but where security is concerned, it

is good to be clear.

# Security

anon_world_readable_only=YES

connect_from_port_20=YES

hide_ids=YES

pasv_min_port=50000

pasv_max_port=60000

These settings, in order

- Make sure only world-readable files and Directories are served.

- Originates FTP port connections from a secure port - so users on the FTP

server cannot try and fake file content.

- Hide the FTP server user IDs and just display "ftp" in directory listings.

This is also a performance boost.

- Set a 50000-60000 port range for passive connections - may enable easier

firewall setup!

# Features

xferlog_enable=YES

ls_recurse_enable=NO

ascii_download_enable=NO

async_abor_enable=YES

In order,

- Enables recording of transfer stats to /var/log/vsftpd.log

- Disables "ls -R", to prevent it being used as a DoS attack. Note - sites

wanting to be copied via the "mirror" program might need to enable this.

- Disables downloading in ASCII mode, to prevent it being used as a DoS

attack (ASCII downloads are CPU heavy).

- Enables older FTP clients to cancel in-progress transfers.

# Performance

one_process_model=YES

idle_session_timeout=120

data_connection_timeout=300

accept_timeout=60

connect_timeout=60

anon_max_rate=50000

In order,

- Activates a faster "one process per connection" model. Note! To maintain

security, this feature is only available on systems with capabilities - e.g.

Linux kernel 2.4.

- Boots off idle users after 2 minutes.

- Boots off idle downloads after 5 minutes.

- Boots off hung passive connects after 1 minute.

- Boots off hung active connects after 1 minute.

- Limits a single client to ~50kbytes / sec download speed.

Step 3) Restart xinetd.

(on RedHat)

/etc/rc.d/init.d/xinetd restart

If you run into problems, check:

1) Your /etc/xinetd.d directory only has one FTP service.

vsftpd.conf