소개

Oracle Cloud Infrastructure의 VCN(가상 네트워크) 내에서 AWS VNC와 마찬가지로 DHCP는 OS에 IP 주소와 DHCP 옵션(DNS 서버 및 검색 도메인(DNS 접미사))을 배포합니다.

이 설정을 OS를 재부팅하지 않고 다시 반영하는 것이 목적입니다.

할 일

기본 DHCP 옵션 설정은 "Internet and VCN Resolver"라는 설정으로 OCI VCN의 내부 DNS 169.254.169.254를 참조하고,
검색 도메인으로 "[VCN DNS label].oraclevcn.com)"이 설정되어 있습니다.

기본적으로 VCN의 이름 확인과 외부 인터넷에 이름 확인이 가능한 상태이지만 엔터프라이즈 내부의 DNS 서버를 참조하도록 "Custom Resolver"로 변경하여 DNS 서버의 IP 주소를 지정하고, 검색 도메인을 'sample.local'로 변경합니다.

전제

OCI VCN 작성됨

OCI Compute OS 작성됨(Oracle Linux 7.7 및 Windows 2016)

OCI DHCP 옵션 변경

OCI VCN 설정을 열고 DHCP 옵션 아래 아래를 눌러 "편집"

'사용자 확인자'로 변경하고 모든 DNS 서버 IP 및 검색 도메인을 입력하십시오

변경 사항 저장

(여담) DNS 서버의 지정은 3개까지. 검색 도메인은 상한 1개만・・!

변경됨

Oracle Linux 7.7에서 DHCP 옵션 반영

OS에 로그인을 루트 사용자로 전환

현재 설정 확인

$ sudo -i

# cat /etc/resolv.conf 
; Any changes made to this file will be overwritten whenever the
; DHCP lease is renewed. To persist changes you must update the
; /etc/oci-hostname.conf file. For more information see
;[https://docs.cloud.oracle.com/iaas/Content/Network/Tasks/managingDHCP.htm#notes]
;
; generated by /usr/sbin/dhclient-script
search vcntokyo1.oraclevcn.com subdmz.vcntokyo1.oraclevcn.com ★ここが変わる
nameserver 169.254.169.254 ★ここが変わる

dhclient 명령을 실행하여 DHCP 옵션을 반영합니다

명령을 실행하고 돌아올 때까지 10 초 정도 걸립니다

설정 확인

# dhclient

# cat /etc/resolv.conf 
; Any changes made to this file will be overwritten whenever the
; DHCP lease is renewed. To persist changes you must update the
; /etc/oci-hostname.conf file. For more information see
;[https://docs.cloud.oracle.com/iaas/Content/Network/Tasks/managingDHCP.htm#notes]
;
; generated by /usr/sbin/dhclient-script
search sample.local　★変わった
nameserver 192.168.250.250　★変わった

dhclient 프로세스가 남아 있기 때문에 KILL

# ps ax |grep dhc
 1574 ?        Ss     0:00 /sbin/dhclient -1 -q -lf /var/lib/dhclient/dhclient-ad083c0c-3c81-XXXX-9d74-XXXXXXX-ens3.lease -pf /var/run/dhclient-ens3.pid -H bastion ens3
 3868 ?        Ss     0:00 dhclient
 3914 pts/0    S+     0:00 grep --color=auto dhc

# kill 3868

Windows Server 2016에서 DHCP 옵션 반영

현재 설정 확인 (길기 때문에 일부 할애)

C:\Users\opc>ipconfig /all

Windows IP Configuration

   Host Name . . . . . . . . . . . . : win1
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : vcntokyo1.oraclevcn.com ★ここが変わる

Ethernet adapter Ethernet:

   Connection-specific DNS Suffix  . : vcntokyo1.oraclevcn.com ★ここが変わる
   Description . . . . . . . . . . . : Broadcom NetXtreme-E Virtual Function
   Physical Address. . . . . . . . . : 02-00-17-00-1D-F7
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::1179:560f:c64f%2(Preferred)
   IPv4 Address. . . . . . . . . . . : 10.1.0.37(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : Thursday, March 5, 2020 9:56:51 PM
   Lease Expires . . . . . . . . . . : Friday, March 6, 2020 9:56:51 PM
   Default Gateway . . . . . . . . . : 10.1.0.1
   DHCP Server . . . . . . . . . . . : 169.254.169.254
   DHCPv6 IAID . . . . . . . . . . . : 33685527
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-25-EE-DA-EC-02-00-17-00-1D-F7
   DNS Servers . . . . . . . . . . . : 169.254.169.254 ★ここが変わる
   NetBIOS over Tcpip. . . . . . . . : Disabled

ipconfig/renew 로 DHCP 옵션을 반영

설정 확인

C:\Users\opc>ipconfig /renew

C:\Users\opc>ipconfig /all

Windows IP Configuration

   Host Name . . . . . . . . . . . . : win1
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : sample.local　★変わった

Ethernet adapter Ethernet:

   Connection-specific DNS Suffix  . : sample.local　★変わった
   Description . . . . . . . . . . . : Broadcom NetXtreme-E Virtual Function
   Physical Address. . . . . . . . . : 02-00-17-00-1D-F7
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::1179:560f:c64f%2(Preferred)
   IPv4 Address. . . . . . . . . . . : 10.1.0.37(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : Thursday, March 5, 2020 9:56:51 PM
   Lease Expires . . . . . . . . . . : Friday, March 6, 2020 10:17:52 PM
   Default Gateway . . . . . . . . . : 10.1.0.1
   DHCP Server . . . . . . . . . . . : 169.254.169.254
   DHCPv6 IAID . . . . . . . . . . . : 33685527
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-25-EE-DA-EC-02-00-17-00-1D-F7
   DNS Servers . . . . . . . . . . . : 192.168.250.250　★変わった
   NetBIOS over Tcpip. . . . . . . . : Disabled

참고

DHCP 옵션

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