icmp请求已收到，但未回复 [英] icmp request received, but doesn't reply

问题描述

我设置了3台CentOS服务器，将server2配置为介于192.168.1.0/24和30.0.0.0/24之间的路由器，但是 ping 无法通过.

I set up 3 CentOS servers, configured server2 as router between 192.168.1.0/24 and 30.0.0.0/24, but ping can't get through.

我尝试从server1 ping 192.168.1.62 ，根据server3上的 tcpdump ，收到了ICMP请求，但它不会生成ICMP响应.

I tried ping 192.168.1.62 from server1, according to tcpdump on server3, ICMP request is received, but it doesn't generate ICMP response.

23:36:06.436243 IP 30.0.0.2 > 192.168.1.62: ICMP echo request, id 23570, seq 2838, length 64
23:36:07.436212 IP 30.0.0.2 > 192.168.1.62: ICMP echo request, id 23570, seq 2839, length 64

设置

服务器

• 服务器1:

  Setup

  Servers

  • server1:

    • eth0-30.0.0.2

    server2:

    • eth0-192.168.1.61
    • eth0:0-30.0.0.1

    server3:

    • eth0-192.168.1.62

    • server1上的路由信息​​:

    • route info on server1:

    • 0.0.0.0 30.0.0.1

    server3上的路由信息​​:

    route info on server3:

    • 30.0.0.0/24 192.168.1.61

    推荐答案

    我正在接收ICMP数据包，但没有看到它们出去.问题与流量穿越多个接口和默认情况下启用反向路径筛选有关.

    I was receiving ICMP packets but did not see them go out. The problem was related to the traffic traversing multiple interfaces and reverse path filtering being on by default...

    我首先启用了火星源日志记录:

    I've enabled martian source logging first:

    $ echo 1 >/proc/sys/net/ipv4/conf/eth2/log_martians
    

    然后有几个选项可以处理它们......我正在启用松散处理它们:

    Then there are several options for what to do with them... I'm enabling loosely handling them:

    $ sysctl net.ipv4.conf.all.rp_filter=2
    

    有关详细信息，请参见以下内容:

    See these for details:

    • http://lartc.org/howto/lartc.kernel.html
    • https://access.redhat.com/site/solutions/53031

    这篇关于icmp请求已收到，但未回复的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！