Linux Birdge网络调试

环境描述

  1. 环境1：使用Linux Bridge 桥接网络

  • 双网卡 em1 ,em2

  • 双网桥 br1–em1 ,br2–em2

    [root@ironic-father ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
    valid_lft forever preferred_lft forever
2: em1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master br1 state UP group default qlen 1000
    link/ether 44:a8:42:0b:eb:53 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::46a8:42ff:fe0b:eb53/64 scope link
    valid_lft forever preferred_lft forever
3: em2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master br2 state UP group default qlen 1000
    link/ether 44:a8:42:0b:eb:54 brd ff:ff:ff:ff:ff:ff
4: em3: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 44:a8:42:0b:eb:55 brd ff:ff:ff:ff:ff:ff
5: em4: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 44:a8:42:0b:eb:56 brd ff:ff:ff:ff:ff:ff
6: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 52:54:00:c3:4b:df brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
    valid_lft forever preferred_lft forever
7: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr0 state DOWN group default qlen 1000
    link/ether 52:54:00:c3:4b:df brd ff:ff:ff:ff:ff:ff
9: br2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 44:a8:42:0b:eb:54 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::bcf6:97ff:fedd:dda9/64 scope link
    valid_lft forever preferred_lft forever
10: br1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 44:a8:42:0b:eb:53 brd ff:ff:ff:ff:ff:ff
    inet 10.199.32.113/24 brd 10.199.32.255 scope global noprefixroute br1
    valid_lft forever preferred_lft forever
    inet6 fe80::46a8:42ff:fe0b:eb53/64 scope link
    valid_lft forever preferred_lft forever
25: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br2 state UNKNOWN group default qlen 1000
    link/ether fe:54:00:e7:be:b2 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::fc54:ff:fee7:beb2/64 scope link
    valid_lft forever preferred_lft forever
  1. 环境2: openvswitch

抓包分析

创建一个dummy接口

ip link add name snooper0 type dummy
ip link set dev snooper0 up

在Bridge中添加设备

Linux Bridge环境：

brctl addif  br2  snooper0
#抓取icmp包
tcpdump -i br2 -vv 'udp and port 67 and port 68'

OpenvSwitch环境：

#添加设备
ip link add name snooper0 type dummy
ip link set dev snooper0 up
#绑定设备
ovs-vsctl add-port br-int snooper0
#镜像流量
ovs-vsctl -- set Bridge br-int mirrors=@m  -- --id=@snooper0 \
get Port snooper0  -- --id=@patch-tun get Port patch-tun \
-- --id=@m create Mirror name=mymirror select-dst-port=@patch-tun \
select-src-port=@patch-tun output-port=@snooper0 select_all=1
#抓包
tcpdump -i br2 -vv 'udp and port 67 and port 68'

#清理
ovs-vsctl clear Bridge br-int mirrors
ovs-vsctl del-port br-int snooper0
ip link delete dev snooper0