这行来自我的/var/log/rsyncd.log文件：

2013/02/08 12:15:28 [13174] name lookup Failed for XXX.XXX.XXX.XXX: Name or service not known
2013/02/08 12:15:28 [13174] connect from UNKNOWN (XXX.XXX.XXX.XXX)

从rsyncd.conf手册页：

reverse lookup

Controls whether the daemon performs a reverse lookup on the client’s
IP address to determine its hostname,which is used for “hosts
allow”/”hosts deny” checks and the “%h” log escape. This is enabled by
default,but you may wish to disable it to save time if you know the
lookup will not return a useful result,in which case the daemon will
use the name “UNDETERMINED” instead.

If this parameter is enabled globally (even by default),rsync
performs the lookup as soon as a client connects,so disabling it for
a module will not avoid the lookup. Thus,you probably want to disable
it globally and then enable it for modules that need the information.

所以我将以下行添加到/etc/rsyncd.conf中的全局conf中

reverse lookup = no

但是,当我停止并启动守护程序时,这行会添加到日志文件中：

2013/02/08 12:47:17 [13675] Unknown Parameter encountered: "reverse lookup" 
2013/02/08 12:47:17 [13675] IGNORING unknown parameter "reverse lookup" 
2013/02/08 12:47:17 [13676] rsyncd version 3.0.7 starting,listening on port 873

这是我服务器上安装的版本：

rsync version 3.0.7 protocol version 30