DHCP：一個網卡和多個子網

我正在設置一個 Debian 作為小型辦公網路的網關。我需要為公司內的不同區域建立三個子網，我將根據 MAC 地址定義哪些 PC 將獲得哪些 IP。

我的問題是：是否可以使用單個 NIC 處理 3 個子網的 DHCP？如何？

我嘗試為每個網路設置虛擬介面，如下所示：

# 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

注意： eth2 使用的是 192.168.1.10，因為盒子目前不是網路網關。這只是暫時的。

然後我像這樣設置我的 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;
}

但是當我嘗試啟動 dhcpd 時，我得到了這個：

# 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!

我對 DHCP 真的很陌生，所以我可能遺漏了一些明顯的東西。我已經在Google上搜尋了一段時間，但我找不到我需要的答案，或者我沒有正確搜尋。

由於三個子網共享相同的介質（eth2），它們應該在相同的內部聲明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 {
   ...
 }
}

實際上只有兩種方法可以做到這一點；

1. 將您的 DHCP 伺服器的 IP 設置為 L3 交換機上每個 VLAN 的“DHCP 助手地址”，然後為伺服器上的那些定義範圍。
2. 將交換機上的 DHCP 伺服器的 NIC 埠設置為攜帶所有適當 VLAN 的 .1q 中繼，然後在伺服器上設置單獨的 vNIC，並為每個 VLAN 設置適當的 IP，然後從那裡開始。

無論哪種方式，都盡量不要只使用一個 NIC，你應該有兩個用於彈性，然後將它們綁定。

引用自：https://serverfault.com/questions/390410