我笔记本用ubuntu的时候连wifi总是掉线重连，解决的途径是要去看/etc/ppp/下的option

ppp就是点对点协议，所有与ppp配置相关的文件都放在这个目录下

那就sudo vim /etc/ppp/option 吧

在两百一十多行的地方有这样一段

# If this option is given, pppd will send an LCP echo-request frame to the
# peer every n seconds. Normally the peer should respond to the echo-request
# by sending an echo-reply. This option can be used with the
# lcp-echo-failure option to detect that the peer is no longer connected.
lcp-echo-interval 4

# If this option is given, pppd will presume the peer to be dead if n
# LCP echo-requests are sent without receiving a valid LCP echo-reply.
# If this happens, pppd will terminate the connection.  Use of this
# option requires a non-zero value for the lcp-echo-interval parameter.
# This option can be used to enable pppd to terminate after the physical
# connection has been broken (e.g., the modem has hung up) in
# situations where no hardware modem control lines are available.
lcp-echo-failure 30

下面一段意思是说lcp-echo-failure这个值设了，我们的拨号客户端pppd就会向你的peer发送一个请求帧，然后等他回复，lcp-echo-failure设为30也就是说如果pppd发了30次请求帧你的peer都没有回，他就认为你的链接断了。而上面那个lcp-echo-interval就是你每次等待回复的时间，默认设为4，如果网不是很给力的话，很容易就超时，被认为要重连，所以就频繁地断连接很烦人。现在把每次等待时间改长一点，设为30，然后就不那么容易掉了。

# If this option is given, pppd will send an LCP echo-request frame to the
# peer every n seconds. Normally the peer should respond to the echo-request
# by sending an echo-reply. This option can be used with the
# lcp-echo-failure option to detect that the peer is no longer connected.
lcp-echo-interval <span style="color:#FF0000;">30</span>

# If this option is given, pppd will presume the peer to be dead if n
# LCP echo-requests are sent without receiving a valid LCP echo-reply.
# If this happens, pppd will terminate the connection.  Use of this
# option requires a non-zero value for the lcp-echo-interval parameter.
# This option can be used to enable pppd to terminate after the physical
# connection has been broken (e.g., the modem has hung up) in
# situations where no hardware modem control lines are available.
lcp-echo-failure 30