seconds between keepalives 设置为10就好了， 这个值有什么含义，服务器为了节省资源采取了一些措施，其中一条就是如果检测一个会话(session)几分钟或者几小时没有数据流入或者流出就会断开这个链接，占着茅坑不拉屎就是说这种情况，设置了putty中keepalive这个值之后比如是10，那putty每隔10秒就给服务器发送一个空数据包，以此来表示我还没拉完屎呢?这样厕所看管员就不会把我们踢出去了。
我这里找到了putty官方网站中关于keepalive的说明：
4.13 The Connection panel
The Connection panel allows you to configure options that apply to more than one type of connection.
4.13.1 Using keepalives to prevent disconnection
If you find your sessions are closing unexpectedly (most often with ‘Connection reset by peer’) after they have been idle for a while, you might want to try using this option.
Some network routers and firewalls need to keep track of all connections through them. Usually, these firewalls will assume a connection is dead if no data is transferred in either direction after a certain time interval. This can cause PuTTY sessions to be unexpectedly closed by the firewall if no traffic is seen in the session for some time.
The keepalive option (‘Seconds between keepalives’) allows you to configure PuTTY to send data through the session at regular intervals, in a way that does not disrupt the actual terminal session. If you find your firewall is cutting idle connections off, you can try entering a non-zero value in this field. The value is measured in seconds; so, for example, if your firewall cuts connections off after ten minutes then you might want to enter 300 seconds (5 minutes) in the box.
Note that keepalives are not always helpful. They help if you have a firewall which drops your connection after an idle period; but if the network between you and the server suffers from breaks in connectivity then keepalives can actually make things worse. If a session is idle, and connectivity is temporarily lost between the endpoints, but the connectivity is restored before either side tries to send anything, then there will be no problem - neither endpoint will notice that anything was wrong. However, if one side does send something during the break, it will repeatedly try to re-send, and eventually give up and abandon the connection. Then when connectivity is restored, the other side will find that the first side doesn't believe there is an open connection any more. Keepalives can make this sort of problem worse, because they increase the probability that PuTTY will attempt to send data during a break in connectivity. (Other types of periodic network activity can cause this behaviour; in particular, SSH-2 re-keys can have this effect. See section 4.19.2.)
在用navicat远程连接数据库之后，一段时间没有操作也会有断开连接这种情况，原理和putty的设置是一样的，在连接的高级设置里面有个keep alive 设置为10或者20就行。