Two modes of FTP operation--XINETD run mode and standalone mode
Original link http://blog.chinaunix.net/uid-22889411-id-59432.html
Like other daemons, VSFTPD provides both standalone and inetd (inetd or xinetd) modes of operation. Simple explanation, standalone one-time start, the operation has been resident in memory, the advantage is that the response to the access signal fast, the disadvantage is the loss of a certain system resources, and therefore often used in the immediate response to the high demand for professional FTP server. inetd on the contrary, because the FTP process is called only when the external connection sends the request, it is not suitable for applications that have a large number of simultaneous connections. In addition, the inetd mode does not occupy system resources. In addition to the effects of both reaction speed and resource occupancy, VSFTPD offers some additional advanced features such as inetd mode support for PER_IP (single IP) restrictions, while standalone mode is more conducive to Pam validation.
1. XINETD operating mode
Most newer systems use the XINETD super-service daemon. Use "vi/etc/xinetd.d/vsftpd" to look at its contents as follows: Disable = no
Socket_type = Stream
wait = no# This means that the device is active and it is using the standard TCP Sockets. If the option in "/etc/vsftpd.conf" is "Listen=yes", log out of it, and then restart xinetd, the command is as follows: $/etc/rc.d/init.d/xinetd Restart it is important to note that the/etc/ Only one FTP service can be opened in the XINETD.D directory. 2. The standalone mode standalone mode facilitates the PAM verification function. Enter this mode first to close the vsftpd under XINETD, set "Disable = yes", or log off the corresponding line in "/etc/inetd.conf". Then modify the options in "/etc/vsftpd.conf" to "Listen=yes".
---------------------------------the difference between "standalone mode" and "xinetd mode" are who would accept the Initi Al connection request. The "standalone mode" would accept the request by itself, but "xinetd mode" would use XINETD to accept the request, fork a Server process, and redirect the connection to the new process. In the case of Standlone mode, it is started as a separate service, does not require system collaboration, does not serve as a system,
If it becomes a xinetd mode, then its service will be limited by the system services, such as the creation of a new service process, but there are shortcomings, if the XINETD service itself is a problem, then the related services will be affected. The difference between--------------------------------------------------------------------------xinetd mode and standalone mode is that services running in xinetd mode represent that the service process does not To daemon execution, take the FTPD process as an example, to run the service in XINETD mode, the situation is that the FTP service itself will listen to Port 21st, but in this mode to run the service, Port 21st by the XINETD process to listen (at this time the FTPD service does not run), If your network card receives a port 21st request, then there is a xinetd process will call the FTPD program, the request data received at Port 21st to the FTPD process to handle, after processing the FTPD process exits, and the xinetd process continues to listen on Port 21st, This is a bit like the Windows svhost process, whereas a service running in standalone mode is a service process, such as FTPD running in memory with the daemon, and receiving a request from Port 21st, which is processed by the FTPD process by a sub-process fork. And the original process continues to listen on port number 21st.
If there is any mistake, please correct me.
Two modes of "Go" ftp run--XINETD run mode and standalone mode