无效的组播接口

Question

我正在尝试使用ping带有命令的指定接口

ping -I re3 192.168.1.1

我知道re3存在于ifconfig

re3: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=8209b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC,LINKSTATE>
        ether e8:de:27:01:7f:e7
        inet6 fe80::eade:27ff:fe01:7fe7%re3 prefixlen 64 scopeid 0x4
        inet 192.168.1.2 netmask 0xffffff00 broadcast 192.168.1.255
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active

不幸的是，我无法 ping 它的网关：

$/root: ping -I re3 192.168.1.1
ping: invalid multicast interface: `re3'

那是什么意思？

更新

$arp 192.168.1.1
? (192.168.1.1) at (incomplete) on re3 expired [ethernet]

Answer 1

对freebsd系统没有太多经验，据我所知，ping尝试：

ping -S 192.168.1.2 192.168.1.1

至于arp

• 如果 arp 无法获取网关的 MAC 地址，那么 freebsd 服务器就失去了与网关的连接。
• 检查服务器的网关是否已启动/正在运行，并检查两者的物理连接。

Answer 2

在 FreeBSD 和 macos 上，该-I标志的行为与人们对 Linux 的期望不同。如果你仔细检查手册页，你会看到：

 -I iface
        Source multicast packets with the given interface **address**.

[强调我的]

So the -I flag actually expects an address, not an interface. You can confirm with something like:

$ ping -I 192.168.1.2 192.168.1.1

But unless your target IP address is a multicast address this will still fail.

To get the behaviour we all know and expect from traceroute and Linux, use the -S flag instead and specify the IP address of the interface you want to use:

$ ping -S 192.168.1.2 192.168.1.1
PING 192.168.1.1 (192.168.1.1) from 192.168.1.20: 56 data bytes
64 bytes from 192.168.1.1: icmp_seq=0 ttl=64 time=5.956 ms