昨天一同事反馈他连服务器上的ftp的速度特别的慢。帮他看了看，就是在登陆的时候速度特别慢，传输的速度其实很快的。ftp用的是proftpd，查了 查帮助手册，在FAQ中发现了这么一段，把它加入到etc/proftpd.conf里面后，重启ftp，FTP就恢复正常速度了。：）

Slow logins

This is probably caused by a firewall or DNS timeout. By default ProFTPD will try to do both DNS and ident lookups against the incoming connection. If these are blocked or excessively delayed a slower than normal login will result. To turn off DNS and ident use:

UseReverseDNS off
IdentLookups off

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