Posted on 2012-11-27 17:16
Milo的海域 阅读(658)
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Linux
今天有同事反应一个网络现象，一个多网卡环境，发给eth1的数据包都被eth0接收了。
第一印象是arp的问题。Google了下得到了确认，有个相关的kernal参数:
arp_ignore - INTEGER
Define different modes for sending replies in response to
received ARP requests that resolve local target IP addresses:
0 - (default): reply for any local target IP address, configured
on any interface
1 - reply only if the target IP address is local address
configured on the incoming interface
2 - reply only if the target IP address is local address
configured on the incoming interface and both with the
sender's IP address are part from same subnet on this interface
3 - do not reply for local addresses configured with scope host,
only resolutions for global and link addresses are replied
4-7 - reserved
8 - do not reply for all local addresses
默认是0，解决这个问题需要配置为1
临时配置下
sysctl -w net.ipv4.conf.all.arp_ignore=1
持久配置
sysctl -w net.ipv4.conf.all.arp_ignore=1
echo 'net.ipv4.conf.all.arp_ignore=1' >> /etc/sysctl.conf
这个弄好可以重启network服务来确保其他机器更新arp cache，如果不方便重启network，自己手动敲arping命令，比如
arping -q -A -c 1 -I eth1 10.197.24.177
这个命令是在 /etc/sysconfig/network-scripts/ifup-eth里看到的
如果机器比较少，也可以直接用arp -d 来删除相关的cache，建议上面的那种发广播的方式。