故障定位三：锁定冲击波病源

　　我们知道，超长帧（超过1518字节）有封闭网络的作用，主要是引起网络速度变慢或网络瘫痪，而短帧（小余64字节）达到一定流量则会对网络设备的工作协议造成一定程度的破坏，引起设备死机，一般在网络中是不容许大量出现的。小包同样存在这样的问题。由于开始Flex5010下挂少量用户交换机，这个时候网络中短帧虽然存在，但是交换机cpu还有能力处理，一旦超过交换机的负荷（增加下挂用户交换机），网络中存在大量冲击波病毒向外发包(发送目的地址并不存在的arp请求，交换机得到请求之后，不断去寻找目的地址，但是实际上不能转发该报文)，当所有的下挂用户电脑中的冲击波同时并发时，交换机这个时候就处理不过来；又因为是小包，故网络带宽并不大。

　　针对上述分析，在Flex5010上做常见病毒acl访问控制，关闭病毒端口。

    启用acl
    Harbour(config)#service acl enable
    针对常见病毒端口，制定相应的规则，阻止其传播。
    Harbour(config)#create acl acl1 tcp DIP any ip-port 113 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl2 udp DIP any ip-port 135 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl3 tcp DIP any ip-port 135 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl4 udp DIP any ip-port 137 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl5 udp DIP any ip-port 138 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl6 tcp DIP any ip-port 139 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl7 udp DIP any ip-port 139 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl8 udp DIP any ip-port 445 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl9 tcp DIP any ip-port 445 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl10 tcp DIP any ip-port 593 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl11 udp DIP any ip-port 593 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl12 tcp DIP any ip-port 1022 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl13 tcp DIP any ip-port 1023 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl14 tcp DIP any ip-port 1025 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl15 tcp DIP any ip-port 1029 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl16 tcp DIP any ip-port 1034 SIP any ip-port 80 deny ports any
    Harbour(config)#create acl acl17 tcp DIP any ip-port 1068 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl18 udp DIP any ip-port 1434 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl19 tcp DIP any ip-port 1871 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl20 tcp DIP any ip-port 2745 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl21 tcp DIP any ip-port 3067 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl22 tcp DIP any ip-port 3127 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl23 tcp DIP any ip-port 3208 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl24 tcp DIP any ip-port 4331 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl25 tcp DIP any ip-port 4334 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl26 tcp DIP any ip-port 4444 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl27 tcp DIP any ip-port any SIP any ip-port 4444 deny ports any
    Harbour(config)#create acl acl28 tcp DIP any ip-port 4510 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl29 tcp DIP any ip-port 4557 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl30 tcp DIP any ip-port 5554 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl31 tcp DIP any ip-port 5800 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl32 tcp DIP any ip-port 5900 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl33 tcp DIP any ip-port 6129 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl34 tcp DIP any ip-port 6667 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl35 tcp DIP any ip-port 9995 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl36 tcp DIP any ip-port 9996 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl37 tcp DIP any ip-port 10080 SIP any ip-port any deny ports any
    Harbour(config)#create acl acl38 tcp DIP any ip-port 20168 SIP any ip-port any deny ports any

    做上述操作之后，网络正常，flex5010再也不会时通时断了。在下班时刻（此时几乎没有什么用户在上网）查看设备端口：

    Harbour(config)#sh po 9 st
    —————————————————————————
                      Port:9 ’s Statistics Information

   Tx good frames     : 0               Tx total frames    : 0
   Tx multicast frames: 0               Tx broadcast frames: 0
   Rx good frames     : 328             Rx total frames    : 328
   Rx multicast frames: 61              Rx broadcast frames: 185

   CRC error frames   : 0               Oversize frames    : 0
   Fragments          : 0               Jabber             : 0
   dropped frames     : 0               Undersize frames   : 0
   Collision          : 0               Late collision     : 0

   Last 5 minutes ucast input rate             0 packets/sec
   Last 5 minutes ucast output rate            0 packets/sec
   Last 5 minutes mcast input rate             0 packets/sec
   Last 5 minutes mcast output rate            0 packets/sec
   Last 5 minutes bcast input rate             0 packets/sec
   Last 5 minutes bcast output rate            0 packets/sec
   Last 5 minutes input rate                   15 bits/sec
   Last 5 minutes output rate                  0 bits/sec
   Harbour(config)#

　　此时网络中仍有冲击波病毒：交换机端口9收到了328个数据包，因交换机启用了acl，对比后认为是病毒并丢弃，结果交换机全部丢弃，传输了0个数据包。第二天通知当地给电脑打好补丁并及时查杀病毒，网络恢复正常运行。

　　后记：

　　网络故障诊断以网络原理、网络配置和网络运行的知识为基础。从故障现象出发，以网络诊断工具为手段获取诊断信息，确定网络故障点，查找问题的根源，排除故障，恢复网络正常运行。

　　解决网络病毒引起的网络突发故障，需要综合利用各种网管工具。营造一个安全顺畅的网络环境，需要用户端电脑及时打好操作系统补丁，更新杀毒软件病毒库；需要我们网管在交换机、路由器设备上及时做好针对各种病毒、木马的acl，过滤一些有害的端口，保障网络的稳定运行。