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    • 네트워크 설정
      linux/centOS 2018. 7. 11. 11:13

      ☆ 네트워크 설정 파일

       

      ■ 네트워크 설정 파일 종류

      /etc/hosts 파일

      /etc/host.conf 파일(/etc/nsswitch.conf)

      /etc/resolv.conf 파일

      /etc/sysconfig/network 파일

      /etc/sysconfig/network-scripts/ifcfg-eth0 파일

       

      ■ 네트워크 설정 확인 명령어

      ethtool 명령어

      ifconfig 명령어

      netstat -nr 명령어

      /etc/resolv.conf 파일

       

       

      (1) /etc/hosts 파일

      /etc/hosts 파일은 아이피(IP)와 호스트 이름(hostname) 또는 도메인 이름(Domain Name)을 맵핑(Mapping)하는 역할을 가진다. 작은 네트워크에서는 DNS을 대신하도록 설정할 수도 있다.

      자세한 내용은 "# man hosts" 매뉴얼을 확인한다.

       

      # cat /etc/hosts

      # Do not remove the following line, or various programs

      # that require network functionality will fail.

      127.0.0.1 localhost.localdomain localhost

      ::1 localhost6.localdomain6 localhost6

      172.16.9.2XX linux2XX.example.com linux2XX -> 어떤걸 쓰던지 ip주소로 실행됨.

       

      #

      # (1) Linux Server List

      #

      172.16.9.200 linux200.example.com linux200

      172.16.9.201 linux201.example.com linux201

      172.16.9.202 linux202.example.com linux202

       

       

      (2) /etc/host.conf 파일

      /etc/host.conf 파일은 이름 요청(도메인 요청, Naming Service Request)시 도메인/이름 검색 순서를 나타낸다.

      자세한 내용은 "# man host.conf" 매뉴얼을 확인한다.

       

      # cat /etc/host.conf (# cat /etc/nsswitch.conf)

      order hosts,bind --> host.conf에 등록되어 있으면 거기서 ip주소를 찾고 만약 host.conf

      파일이 없다면 bind서버(dns서버)에서 ip주소를 찾는다

      -> (ㄱ) hosts : /etc/hosts 파일을 검색

      -> (ㄴ) bind : DNS 서버에서 검색

       

      웹브라우저

      (예) http://www.daum.net -> (ㄱ) /etc/hosts -> (ㄴ) DNS(/etc/resolv.conf)

       

       

      (3) /etc/resolv.conf 파일

      이름 요청을 할 DNS 서버를 지정할 때 사용하는 파일이다.

       

      # cat /etc/resolv.conf

      search example.com --> search 뒤에 쓰인 도메인은 생략하고 사용 가능하다.

      ex) nslookup www 만 써도 nslookup www.example.com과 같다.

      nameserver 168.126.63.1 /* 168.126.63.1 : kns.kornet.net */

      nameserver 168.126.63.2 /* 168.126.63.2 : kns.kornet.net */

      -> 대표적인 ISP DNS 주소 확인

      (코넷 ) C:\> nslookup –q=NS kornet.net (IP: 211.216.50.150, 211.216.50.160)

      (보라넷) C:\> nslookup –q=NS bora.net (IP: 164.124.101.31, 203.248.240.31)

      (파워콤) C:\> nslookup –q=NS powercom.com (IP: 216.69.185.26, 208.109.255.26)

      (하나로) C:\> nslookup -q=NS hanaro.net (IP: 210.180.98.85, 221.139.108.194)

       

       

      (4) /etc/sysconfig/network 파일

      시스템의 호스트이름/기본라우터 정보를 지정할 때 사용하는 파일이다.

       

      # cd /etc/sysconfig

      # ls

      apm-scripts/ grub lm_sensors readonly-root

      apmd hidd mkinitrd/ rhn/

      atd hsqldb modules/ samba

      auditd httpd named saslauthd

      authconfig hwconf named.rpmnew selinux@

      autofs i18n netconsole sendmail

      bluetooth i18n.old network smartmontools

      cbq/ init network-scripts/ spamassassin

      clock ip6tables-config networking/ squid

      conman iptables-config nfs syslog

      console/ irda nspluginwrapper system-config-securitylevel

      cpuspeed irqbalance ntpd system-config-users

      crond kdump pand tux

      desktop kernel pm-action udev-stw

      dovecot keyboard prelink vncservers

      dund krb524 raid-check wpa_supplicant

      firstboot kudzu rawdevices xinetd

       

      # cat network

      NETWORKING=yes /* NIC 카드 사용 여부 */

      NETWORKING_IPV6=no /* IPv6 사용 여부 */

      HOSTNAME=linux249.example.com /* 호스트 이름 */

      GATEWAY=172.16.0.1 /* Gateway IP 주소(EX: defaultrouter) */

       

      (5) /etc/sysconfig/network-scripts/ifcfg-eth0 파일

      NIC(EX: eth0)의 IP 설정을 할 때 사용하는 파일이다.

       

      # cd /etc/sysconfig/network-scripts

      # ls

      ifcfg-eth0 ifdown-ppp* ifup-ipsec* ifup-sl*

      ifcfg-lo ifdown-routes* ifup-ipv6* ifup-tunnel*

      ifdown@ ifdown-sit* ifup-ipx* ifup-wireless*

      ifdown-bnep* ifdown-sl* ifup-isdn@ init.ipv6-global*

      ifdown-eth* ifdown-tunnel* ifup-plip* net.hotplug*

      ifdown-ippp* ifup@ ifup-plusb* network-functions

      ifdown-ipsec* ifup-aliases* ifup-post* network-functions-ipv6

      ifdown-ipv6* ifup-bnep* ifup-ppp*

      ifdown-isdn@ ifup-eth* ifup-routes*

      ifdown-post* ifup-ippp* ifup-sit*

       

      # cat ifcfg-eth0

      # Intel Corporation 82545EM Gigabit Ethernet Controller (Copper)

      DEVICE=eth0 /* NIC Device Name */

      BOOTPROTO=static /* static or none : 고정 IP 설정 */

      BROADCAST=172.16.255.255 /* Broadcast Address */

      HWADDR=00:0C:29:B6:F4:26 /* MAC Address */

      IPADDR=172.16.9.249 /* IP Address */

      NETMASK=255.255.0.0 /* Netmask */

      NETWORK=172.16.0.0 /* Network Number */

      ONBOOT=yes /* 부팅시에 NIC(EX: eth0) 활성화 여부 */

      or

      # Intel Corporation 82545EM Gigabit Ethernet Controller (Copper)

      DEVICE=eth0

      BOOTPROTO=none

      BROADCAST=172.16.10.255

      HWADDR=00:0c:29:18:9e:b2

      IPADDR=172.16.10.249

      NETMASK=255.255.255.0

      NETWORK=172.16.10.0

      ONBOOT=yes

      GATEWAY=172.16.10.1

      TYPE=Ethernet

       

       

       

      [참고] /etc/sysconfig/networking 디렉토리

      # cd /etc/sysconfig/networking

      # ls

      devices/ profiles/

       

      # cd devices

      # ls

      #

      -> 내용이 없다. (device 디렉토리 내에는 백업본이 들어있기 때문에 있는걸 지워도 상관없다. 없는게 정상이다.)

       

      # cd ../profiles

      # ls

      default/

       

      # cd default

      # ls

      #

      -> 내용이 없다. (초기에는 아무 내용이 없기 때문에 디렉토리내의 파일을 지워도 무방하다.)

       

       

      [참고] /etc/sysconfig/network-scripts/ifcfg-eth<N> 파일 예제

      ■ 고정 IP 설정 예(Static IP 설정) /* IP를 고정을 할당 */

      # cat /etc/sysconfig/network-scripts/ifcfg-eth0

      -----------------------------------------------

      DEVICE=eth0

      BOOTPROTO=none or BOOTPROTO=static

      ONBOOT=yes

      NETWORK=172.16.0.0

      NETMASK=255.255.0.0

      IPADDR=172.16.9.249

      USERCTL=no

      -----------------------------------------------

       

      ■ 동적 IP 설정 예(Dynamic IP 설정) /* DHCP 서버로 부터 IP 할당 */

      # cat /etc/sysconfig/network-scripts/ifcfg-eth0

      -----------------------------------------------

      DEVICE=eth0

      BOOTPROTO=dhcp

      ONBOOT=yes

      -----------------------------------------------

      (6) 현재 설정 확인

       

      (현재 IP 설정 확인)

      # ifconfig /* 활성화(Activate) 된 인터페이스에 대한서만 정보 확인 */

      # ifconfig -a /* 활성화(Activate) + 비활성화(Deactivate) 된 인터페이스 정보 확인 */

       

      # ifconfig

      eth0 Link encap:Ethernet HWaddr 00:0C:29:B6:F4:26

      inet addr:172.16.9.249 Bcast:172.16.255.255 Mask:255.255.0.0

      inet6 addr: fe80::20c:29ff:feb6:f426/64 Scope:Link

      UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

      RX packets:123511 errors:0 dropped:0 overruns:0 frame:0

      TX packets:2339 errors:0 dropped:0 overruns:0 carrier:0

      collisions:0 txqueuelen:1000

      RX bytes:16233959 (15.4 MiB) TX bytes:196066 (191.4 KiB)

       

      lo Link encap:Local Loopback

      inet addr:127.0.0.1 Mask:255.0.0.0

      inet6 addr: ::1/128 Scope:Host

      UP LOOPBACK RUNNING MTU:16436 Metric:1

      RX packets:3277 errors:0 dropped:0 overruns:0 frame:0

      TX packets:3277 errors:0 dropped:0 overruns:0 carrier:0

      collisions:0 txqueuelen:0

      RX bytes:3084485 (2.9 MiB) TX bytes:3084485 (2.9 MiB)

      -> 현재 활성화된(Active) NIC 설정을 보여준다.

       

      # ifconfig –a

      eth0 Link encap:Ethernet HWaddr 00:0C:29:B6:F4:26

      inet addr:172.16.9.249 Bcast:172.16.255.255 Mask:255.255.0.0

      inet6 addr: fe80::20c:29ff:feb6:f426/64 Scope:Link

      UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

      RX packets:124123 errors:0 dropped:0 overruns:0 frame:0

      TX packets:2339 errors:0 dropped:0 overruns:0 carrier:0

      collisions:0 txqueuelen:1000

      RX bytes:16286941 (15.5 MiB) TX bytes:196066 (191.4 KiB)

       

      lo Link encap:Local Loopback

      inet addr:127.0.0.1 Mask:255.0.0.0

      inet6 addr: ::1/128 Scope:Host

      UP LOOPBACK RUNNING MTU:16436 Metric:1

      RX packets:3277 errors:0 dropped:0 overruns:0 frame:0

      TX packets:3277 errors:0 dropped:0 overruns:0 carrier:0

      collisions:0 txqueuelen:0

      RX bytes:3084485 (2.9 MiB) TX bytes:3084485 (2.9 MiB)

       

      sit0 Link encap:IPv6-in-IPv4

      NOARP MTU:1480 Metric:1

      RX packets:0 errors:0 dropped:0 overruns:0 frame:0

      TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

      collisions:0 txqueuelen:0

      RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

      -> 모든 NIC의 상태 정보(활성화된 NIC + 비활성화된 NIC)를 보여준다.

       

      # netstat –nr /* -n : numeric, -r : routing table */

      Kernel IP routing table

      Destination Gateway Genmask Flags MSS Window irtt Iface

      169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0

      172.16.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0

      0.0.0.0 172.16.0.1 0.0.0.0 UG 0 0 0 eth0

      -> 라우팅 테이블 정보를 보여준다.

      -> 172.16.0.1 아이피는 기본 라우터를 나타낸다.

       

      # cat /etc/resolv.conf

      search example.com

      nameserver 168.126.63.1 /* kns.kornet.net : 168.126.63.1 */

      nameserver 168.126.63.2

       

       

       

      [참고] NIC카드 설정값 확인하는 명령어(ethtool)

      ■ ethtool

      Display or change ethernet card settings

      -> 전송속도 선택(10M/100M/1000M)

      -> 전이중/반이중 방식 선택(Full Duplex, Half Duplex)

      -> (사용방법 확인)

      # ethtool

      # man ethtool

       

      # ethtool eth0

      Settings for eth0:

      Supported ports: [ TP ]

      Supported link modes: 1000baseT/Full

      Supports auto-negotiation: No

      Advertised link modes: Not reported

      Advertised auto-negotiation: No

      Speed: 1000Mb/s

      Duplex: Full

      Port: Twisted Pair

      PHYAD: 0

      Transceiver: internal

      Auto-negotiation: off

      Link detected: yes

      or

      Settings for eth0:

      Current message level: 0x00000007 (7)

      Link detected: yes

      or

      Settings for eth0:

      Supported ports: [ TP ]

      Supported link modes: 10baseT/Half 10baseT/Full

      100baseT/Half 100baseT/Full

      1000baseT/Full

      Supports auto-negotiation: Yes

      Advertised link modes: 10baseT/Half 10baseT/Full

      100baseT/Half 100baseT/Full

      1000baseT/Full

      Advertised auto-negotiation: Yes

      Speed: 1000Mb/s

      Duplex: Full

      Port: Twisted Pair

      PHYAD: 0

      Transceiver: internal

      Auto-negotiation: on

      Supports Wake-on: d

      Wake-on: d

      Current message level: 0x00000007 (7)

      Link detected: yes

       

       

       

      (정리) 네트워크 설정 확인

      (ㄱ) 물리적인 연결 확인

      # ethtool eth0

      (ㄴ) IP 확인

      # ifconfig

      (ㄷ) defaultrouter 확인

      # netstat –nr

      (ㄹ) DNS 클라이언트 설정 확인

      # cat /etc/resolv.conf (# cat /etc/host.conf, /etc/nsswitch.conf)

        

      ☆ 네트워크 설정 툴 종류 

       

       

      ■ 네트워크 설정 툴

      # export LANG=en_US.UTF-8 (# export LANG=C)

      (TUI) # system-config-network-tui (# setup)

      (GUI) # system-config-network-gui (# neat)

      # service network restart

       

       

      [EX] 네트워크 설정 툴에 대한 실습

       

      ① 툴 종류 확인

      # yum list | grep system-config

      system-config-date.noarch 1.8.12-5.el5.centos installed

      system-config-display.noarch 1.0.48-4.el5 installed

      system-config-httpd.noarch 5:1.3.3.3-1.el5 installed

      system-config-kdump.noarch 1.0.14-5.el5_9 installed

      system-config-keyboard.noarch 1.2.11-1.el5 installed

      system-config-language.noarch 1.1.18-3.el5 installed

      system-config-lvm.noarch 1.1.5-13.el5 installed

      system-config-netboot.noarch 0.1.45.1-5.el5 installed

      system-config-netboot-cmd.noarch 0.1.45.1-5.el5 installed

      system-config-network.noarch 1.3.99.21-1.el5 installed

      system-config-network-tui.noarch 1.3.99.21-1.el5 installed

      system-config-nfs.noarch 1.3.23-2.el5 installed

      system-config-printer.x86_64 0.7.32.10-3.el5 installed

      system-config-printer-libs.x86_64 0.7.32.10-3.el5 installed

      system-config-rootpassword.noarch 1.1.9.1-1 installed

      system-config-samba.noarch 1.2.41-5.el5 installed

      system-config-securitylevel.x86_64 1.6.29.1-6.el5 installed

      system-config-securitylevel-tui.x86_64 1.6.29.1-6.el5 installed

      system-config-services.noarch 0.9.4-5.el5 installed

      system-config-soundcard.noarch 2.0.6-1.el5 installed

      system-config-users.noarch 1.2.51-7.el5 installed

      system-config-audit.x86_64 0.4.10-7.el5 base

      system-config-bind.noarch 4.0.3-6.el5.centos base

      system-config-boot.x86_64 0.2.13-1.el5 base

      system-config-cluster.noarch 1.0.57-16 base

      system-config-kickstart.noarch 2.6.19.9-2.el5 base

       

      [참고] redhat-config-* && system-config-*

      RHEL 3.X : redhat-config-* (CentOS 3.X)

      RHEL 4.X : system-config-* (CentOS 4.X)

       

      # system-config-[TAB][TAB]

      system-config-authentication system-config-nfs

      system-config-date system-config-packages

      system-config-display system-config-printer

      system-config-httpd system-config-rootpassword

      system-config-kdump system-config-samba

      system-config-keyboard system-config-securitylevel

      system-config-language system-config-securitylevel-tui

      system-config-lvm system-config-services

      system-config-network system-config-soundcard

      system-config-network-cmd system-config-time

      system-config-network-gui system-config-users

      system-config-network-tui

       

       

      ② IP 변경 설정

       

      ■ IP 변경 (172.16.9.2XX -> 172.16.9.1XX)

       

      # export LANG=C (# export LANG=en_US.UTF-8)

      # system-config-network-tui

      -> "Edit Devices"

      -> "eth0 (eth0) - Advanced Micro Devices [AMD] 79c970 [PCnet32 LANCE]"

      -------------------------------------------

      Name eth0

      Device eth0

      Use DHCP [ ]

      Static IP 172.16.9.1XX /* (EX) 172.16.9.202 -> 172.16.9.102 */

      Netmask 255.255.0.0

      Default gateway IP 172.16.0.1

      -------------------------------------------

       

      # cat /etc/sysconfig/network-scripts/ifcfg-eth0

      # Intel Corporation 82545EM Gigabit Ethernet Controller (Copper)

      DEVICE=eth0

      BOOTPROTO=none

      BROADCAST=172.16.255.255

      HWADDR=00:0c:29:b6:f4:26

      IPADDR=172.16.9.1XX

      NETMASK=255.255.0.0

      NETWORK=172.16.0.0

      ONBOOT=yes

      GATEWAY=172.16.0.1

      TYPE=Ethernet

       

      # ifconfig eth0

      eth0 Link encap:Ethernet HWaddr 00:0C:29:B6:F4:26

      inet addr:172.16.9.2XX Bcast:172.16.255.255 Mask:255.255.0.0

      inet6 addr: fe80::20c:29ff:feb6:f426/64 Scope:Link

      UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

      RX packets:133978 errors:0 dropped:0 overruns:0 frame:0

      TX packets:2344 errors:0 dropped:0 overruns:0 carrier:0

      collisions:0 txqueuelen:1000

      RX bytes:17235237 (16.4 MiB) TX bytes:196336 (191.7 KiB)

       

      # service network restart

      Shutting down interface eth0: [ OK ]

      Shutting down loopback interface: [ OK ]

      Bringing up loopback interface: [ OK ]

      Bringing up interface eth0: [ OK ]

       

      # ifconfig eth0

      -> IP 설정 확인

       

       

      ③ IP 설정 복원

       

      ■ IP 변경 (172.16.9.1XX -> 172.16.9.2XX)

       

      # system-config-network-gui &

      -------------------------------------------

      Address 172.16.9.2XX /* 172.16.9.102 -> 172.16.9.202 */

      Subnet Mast 255.255.0.0

      Default gateway Address 172.16.0.1

      -------------------------------------------

       

      # cat /etc/sysconfig/network-scripts/ifcfg-eth0

      # Intel Corporation 82545EM Gigabit Ethernet Controller (Copper)

      DEVICE=eth0

      BOOTPROTO=none

      BROADCAST=172.16.255.255

      HWADDR=00:0c:29:b6:f4:26

      IPADDR=172.16.9.2XX

      NETMASK=255.255.0.0

      NETWORK=172.16.0.0

      ONBOOT=yes

      GATEWAY=172.16.0.1

      TYPE=Ethernet

      USERCTL=no

      IPV6INIT=no

      PEERDNS=yes

       

      # ifconfig eth0

      eth0 Link encap:Ethernet HWaddr 00:0C:29:B6:F4:26

      inet addr:172.16.9.1XX Bcast:172.16.255.255 Mask:255.255.0.0

      inet6 addr: fe80::20c:29ff:feb6:f426/64 Scope:Link

      UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

      RX packets:140660 errors:0 dropped:0 overruns:0 frame:0

      TX packets:2379 errors:0 dropped:0 overruns:0 carrier:0

      collisions:0 txqueuelen:1000

      RX bytes:17903781 (17.0 MiB) TX bytes:202318 (197.5 KiB)

       

      # service network restart

      Shutting down interface eth0: [ OK ]

      Shutting down loopback interface: [ OK ]

      Bringing up loopback interface: [ OK ]

      Bringing up interface eth0: [ OK ]

       

      # ifconfig eth0

      -> IP 설정 확인

       

       

      ■ Network 설정 툴의 종류

      (GUI) # system-config-network-gui (# neat)

      (TUI) # system-config-network-tui (# setup)

       

      ■ IP 설정/변경 방법

      - "네트워크 설정 툴" 사용하는 경우

      # system-config-network-tui

      # service network restart

      - "직접 설정"하는 경우

      # vi /etc/sysconfig/network-scripts/ifcfg-eth0

      # service network restart

       

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