Red Hat Knowledgebase

The default value for maximum number of simultaneous vsftpd connections coming from the same source FTP client is unlimited. The max_per_ip vsftpd directive's value of 0 means there is no connection limit.

In order to limit the number of connections from the same source to a specific number, the /etc/vsftpd/vsftpd.conf file should be edited. Listed below is an example vsftpd.conf file:

pam_service_name=vsftpd
userlist_enable=YES
#enable for standalone mode
listen=YES
tcp_wrappers=YES
max_per_ip=2

The example illustrates how one can restrict a specific host to 2 concurrent connections. After modifying the vsftpd.conf file, restart vsftpd for the changes to take effect with:

service vsftpd restart

Once the maximum connection limit is reached, the error listed below will be displayed to the other users from the same source attempting to connect to the same FTP server:

421 There are too many connections from your internet address.