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DHCP：一个 NIC 和多个子网

tag-icon • tag-icon debian dhcp isc-dhcp
DHCP：一个 NIC 和多个子网

我正在设置 Debian 作为小型办公网络的网关。我需要为公司内的不同区域设置三个子网，并且我将根据 MA​​C 地址定义哪些 PC 将获得哪个 IP。

我的问题是：是否可以使用单个 NIC 处理 3 个子网的 DHCP？怎么样？

我尝试像这样为每个网络设置虚拟接口：

# ip addr show dev eth2
4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 6c:f0:49:a4:47:38 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.10/24 brd 192.168.1.255 scope global eth2
    inet 10.1.2.1/24 brd 10.1.2.255 scope global eth2:1
    inet 10.1.3.1/24 brd 10.1.3.255 scope global eth2:2
    inet 10.1.1.1/24 brd 10.1.1.255 scope global eth2:0
    inet6 fe80::6ef0:49ff:fea4:4738/64 scope link 
       valid_lft forever preferred_lft forever

笔记：eth2 使用 192.168.1.10，因为该盒子目前不是网络网关。这只是暂时的。

然后我像这样设置我的 dhcpd.conf：

ddns-update-style interim;
option domain-name "mydomain.com";
option domain-name-servers ns1.mydomain.com;
default-lease-time 86400;
max-lease-time 86400;
authoritative;
log-facility local7;

subnet 10.1.1.0 netmask 255.255.255.0 {
        range 10.1.1.100 10.1.1.254;
        default-lease-time 86400;
        max-lease-time 86400;
        option routers 10.1.1.1;
        option ip-forwarding off;
        option broadcast-address 10.1.1.255;
        option subnet-mask 255.255.255.0;
        option ntp-servers 10.1.1.1;
        option domain-name-servers 10.1.1.1;
}

subnet 10.1.2.0 netmask 255.255.255.0 {
        range 10.1.2.100 10.1.2.254;
        default-lease-time 86400;
        max-lease-time 86400;
        option routers 10.1.2.1;
        option ip-forwarding off;
        option broadcast-address 10.1.2.255;
        option subnet-mask 255.255.255.0;
        option ntp-servers 10.1.2.1;
        option domain-name-servers 10.1.2.1;
}

subnet 10.1.3.0 netmask 255.255.255.0 {
        range 10.1.3.100 10.1.3.254;
        default-lease-time 86400;
        max-lease-time 86400;
        option routers 10.1.3.1;
        option ip-forwarding off;
        option broadcast-address 10.1.3.255;
        option subnet-mask 255.255.255.0;
        option ntp-servers 10.1.3.1;
        option domain-name-servers 10.1.3.1;
}

但是当我尝试启动 dhcpd 时出现了以下信息：

# dhcpd -4 eth2:0 eth2:1 eth2:2
Internet Systems Consortium DHCP Server 4.1.1-P1
Copyright 2004-2010 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Wrote 0 leases to leases file.

No subnet declaration for eth2:2 (no IPv4 addresses).
** Ignoring requests on eth2:2.  If this is not what
   you want, please write a subnet declaration
   in your dhcpd.conf file for the network segment
   to which interface eth2:2 is attached. **


No subnet declaration for eth2:1 (no IPv4 addresses).
** Ignoring requests on eth2:1.  If this is not what
   you want, please write a subnet declaration
   in your dhcpd.conf file for the network segment
   to which interface eth2:1 is attached. **


No subnet declaration for eth2:0 (no IPv4 addresses).
** Ignoring requests on eth2:0.  If this is not what
   you want, please write a subnet declaration
   in your dhcpd.conf file for the network segment
   to which interface eth2:0 is attached. **


Not configured to listen on any interfaces!

我对 DHCP 还很陌生，所以我可能遗漏了一些显而易见的东西。我在 Google 上搜索了一段时间，但找不到我需要的答案，或者我搜索的方式不对。

答案1

由于三个子网共享相同的介质（eth2），因此应在相同的内部声明它们shared-network：

shared-network my-net {
  subnet 10.1.1.0 netmask 255.255.255.0 {
    ...
  }

  subnet 10.1.2.0 netmask 255.255.255.0 {
    ...
  }

  subnet 10.1.3.0 netmask 255.255.255.0 {
    ...
  }
}

答案2

实际上只有两种方法可以做到这一点；

  1. 将 DHCP 服务器的 IP 设置为 L3 交换机上每个 VLAN 的“DHCP 帮助器地址”，然后定义服务器上这些地址的范围。
  2. 将交换机上的 DHCP 服务器的 NIC 端口设置为承载所有适当 VLAN 的 .1q 中继，然后在服务器上为每个 VLAN 使用适当的 IP 设置单独的 vNIC，并从那里开始。

无论哪种方式，请尝试不要仅使用单个 NIC，您应该使用两个 NIC 来提高弹性，然后将它们绑定在一起。

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