Ftp to run two modes of operation mode and standalone mode --xinetd
Like other daemons, like, vsftpd provides standalone and inetd (inetd or xinetd) two modes of operation. Briefly explain, standalone one-time activation, during operation has been resident in memory, the advantage of quick access signal response, the disadvantage is the loss of a certain amount of system resources, so often applied to real-time response requirements of high professional FTP server . inetd On the contrary, because the process is called only when the FTP connection request is sent externally, and therefore not suitable for connecting a larger number of systems at the same time. In addition, inetd mode does not take up system resources. In addition to the two effects of reaction speed and footprint, vsftpd also provides some additional advanced features such as inetd mode support per_IP (single IP) restrictions, while standalone mode is more conducive to the application of PAM authentication functions.
1. xinetd mode of operation
Most newer system uses xinetd super service daemon. Use "vi /etc/xinetd.d/vsftpd" look at its contents, as follows:
disable = NO
socket_type = Stream
the wait = NO
This indicates that the device is activated, it is using the standard TCP Sockets.
If there is "/etc/vsftpd.conf" option in the "listen = YES", it is written off
the final restart xinetd, the following command:
$ /etc/rc.d/init.d/xinetd restart
should be noted that " /etc/xinetd.d "directory can only open an FTP service.
2. standalone mode
standalone mode PAM facilitate verification. This mode is entered under the first close vsftpd xinetd, set
"disable = yes", or written off "/etc/inetd.conf" in the corresponding row. Then modify "/etc/vsftpd.con
f" option in the "listen = YES".
The difference between “standalone mode” and “xinetd mode” is who will accept the initial connection request. The “standalone mode” will accept the request by itself, but “xinetd mode” will use xinetd to accept the request, fork a server process, and redirect the connection to the new process.
If standlone mode, then it is launched as a separate service, the system does not need cooperation, not as a system service,
If we become xinetd mode, it is necessary to service the restricted system services, such as creating a new service process, but there are also disadvantages, if xinetd service itself is a problem, then the associated services will also be affected.
Difference xinetd mode and standalone mode
Xinetd mode service indicates that the service is running in daemon process is not executed, for example in order to process it FTPD, run the service with xinetd mode, that is the case, is in itself FTP service listens on port 21, but at this modes run this service, then port 21 by xinetd process to monitor (this time FTPD service is not running), if your card has received port 21 request, the process will have to call FTPD xinetd program, will be 21 port received request data handed over to the FTPD process to deal with, dealt with FTPD process exits, and xinetd process continue to monitor port 21, which is somewhat similar to the windows svhost process; the service running in standalone mode is the service process as ftpd as a daemon running in memory after receiving the request from the port 21 of the fork a child process fTPD process for processing, and the original process continues to listen on port 21.
