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DevOps를 위한 도커와 쿠버네티스 1-2. Linux Network Namespace 2021.08.11

DevOps를 위한 도커와 쿠버네티스 1-2. Linux Network Namespace

2021. 8. 11. 23:32

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root@devops:~# uname -a

Linux devops86 5.4.0-80-generic #90-Ubuntu SMP Fri Jul 9 22:49:44 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

root@devops:~# cat /etc/*release

DISTRIB_DESCRIPTION="Ubuntu 20.04.2 LTS"

## 네트워크 namespace를 만들고 생성한 namespace에 웹서버(nginx) 실행

root@devops:~# ip netns list

root@devops:~# ip netns add uengine1

root@devops:~# ip link

root@devops:~# ip link add veth0 type veth peer name veth1

root@devops:~# ip -br link

lo               UNKNOWN        00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
ens18            UP             92:5c:0d:39:99:b2 <BROADCAST,MULTICAST,UP,LOWER_UP>
docker0          DOWN           02:42:5b:86:7f:85 <NO-CARRIER,BROADCAST,MULTICAST,UP>
veth1@veth0      DOWN           86:8a:10:05:ad:bf <BROADCAST,MULTICAST,M-DOWN>
veth0@veth1      DOWN           86:9c:b2:e1:13:ec <BROADCAST,MULTICAST,M-DOWN>

root@devops:~# ip netns exec uengine1 ip -br link

lo DOWN 00:00:00:00:00:00 <LOOPBACK>

root@devops:~# ip netns exec uengine1 ip link set dev lo up

root@devops:~# ip netns exec uengine1 ip link

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

# 네트워크 디바이스 연결

root@devops:~# ip link set veth1 netns uengine1

root@devops:~# ip -br link

lo               UNKNOWN        00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
ens18            UP             92:5c:0d:39:99:b2 <BROADCAST,MULTICAST,UP,LOWER_UP>
docker0          DOWN           02:42:5b:86:7f:85 <NO-CARRIER,BROADCAST,MULTICAST,UP>
veth0@if4        DOWN           86:9c:b2:e1:13:ec <BROADCAST,MULTICAST>

root@devops:~# ip netns exec uengine1 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
veth1@if5 DOWN 86:8a:10:05:ad:bf <BROADCAST,MULTICAST>

root@devops:~# ip address add 10.24.70.100/24 dev veth0

root@devops:~# ip netns exec uengine1 ip address add 10.24.70.101/24 dev veth1

root@devops:~# ip netns exec uengine1 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
veth1@if5 DOWN 86:8a:10:05:ad:bf <BROADCAST,MULTICAST>

root@devops:~# ip -br link

lo               UNKNOWN        00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
ens18            UP             92:5c:0d:39:99:b2 <BROADCAST,MULTICAST,UP,LOWER_UP>
docker0          DOWN           02:42:5b:86:7f:85 <NO-CARRIER,BROADCAST,MULTICAST,UP>
veth0@if4        DOWN           86:9c:b2:e1:13:ec <BROADCAST,MULTICAST>

root@devops:~# ip link set dev veth0 up

# namespace 디바이스 활성화

root@devops86:~# ip netns exec uengine1 ip link set dev veth1 up

root@devops:~# ip -br link

lo               UNKNOWN        00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
ens18            UP             92:5c:0d:39:99:b2 <BROADCAST,MULTICAST,UP,LOWER_UP>
docker0          DOWN           02:42:5b:86:7f:85 <NO-CARRIER,BROADCAST,MULTICAST,UP>
veth0@if4        UP             86:9c:b2:e1:13:ec <BROADCAST,MULTICAST,UP,LOWER_UP>

root@devops:~# ip netns exec uengine1 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
veth1@if5 UP 86:8a:10:05:ad:bf <BROADCAST,MULTICAST,UP,LOWER_UP>

root@devops:~# ip netns exec uengine1 ip addr

root@devops:~# ip addr

root@devops:~# ping 10.24.70.100

PING 10.24.70.100 (10.24.70.100) 56(84) bytes of data.
64 bytes from 10.24.70.100: icmp_seq=1 ttl=64 time=0.108 ms
64 bytes from 10.24.70.100: icmp_seq=2 ttl=64 time=0.213 ms

root@devops:~# ping 10.24.70.101

PING 10.24.70.101 (10.24.70.101) 56(84) bytes of data.
64 bytes from 10.24.70.101: icmp_seq=1 ttl=64 time=0.220 ms
64 bytes from 10.24.70.101: icmp_seq=2 ttl=64 time=0.073 ms

root@devops:~# ip route

default via 218.236.22.254 dev ens18 proto static
10.24.70.0/24 dev veth0 proto kernel scope link src 10.24.70.100
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown
218.236.22.0/24 dev ens18 proto kernel scope link src 218.236.22.86

root@devops:~# apt install nginx-core -y

Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
fontconfig-config fonts-dejavu-core libfontconfig1 libgd3 libjbig0 libjpeg-turbo8 libjpeg8 libnginx-mod-http-image-filter
libnginx-mod-http-xslt-filter libnginx-mod-mail libnginx-mod-stream libtiff5 libwebp6 libxpm4 nginx-common
Suggested packages:
libgd-tools fcgiwrap nginx-doc ssl-cert
The following NEW packages will be installed:
fontconfig-config fonts-dejavu-core libfontconfig1 libgd3 libjbig0 libjpeg-turbo8 libjpeg8 libnginx-mod-http-image-filter
libnginx-mod-http-xslt-filter libnginx-mod-mail libnginx-mod-stream libtiff5 libwebp6 libxpm4 nginx-common nginx-core
0 upgraded, 16 newly installed, 0 to remove and 0 not upgraded.
Need to get 2428 kB of archives.
After this operation, 7846 kB of additional disk space will be used.
Get:1 http://kr.archive.ubuntu.com/ubuntu focal/main amd64 fonts-dejavu-core all 2.37-1 [1041 kB]
…

root@devops:~# curl 127.0.0.1

<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
nginx.org.

Commercial support is available at
nginx.com.

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

root@devops:~# systemctl status nginx

● nginx.service - A high performance web server and a reverse proxy server
     Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
     Active: active (running) since Thu 2021-08-05 02:06:34 UTC; 47s ago
       Docs: man:nginx(8)
   Main PID: 3928 (nginx)
      Tasks: 3 (limit: 4617)
     Memory: 7.5M
     CGroup: /system.slice/nginx.service
             ├─3928 nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
             ├─3929 nginx: worker process
             └─3930 nginx: worker process

Aug 05 02:06:34 devops systemd[1]: Starting A high performance web server and a reverse proxy server...
Aug 05 02:06:34 devops systemd[1]: Started A high performance web server and a reverse proxy server.

root@devops:~# systemctl stop nginx

root@devops:~# curl 127.0.0.1

curl: (7) Failed to connect to 127.0.0.1 port 80: Connection refused

# 웹서버 실행(기본 80번 포트)

root@devops:~# ip netns exec uengine1 nginx -g 'daemon off;'

root@devops:~# curl localhost

curl: (7) Failed to connect to localhost port 80: Connection refused

root@devops:~# curl 10.24.70.101:80

curl: (7) Failed to connect to 10.24.70.101 port 80: Connection refused

## 2개의 네트워크 namespace를 만들고 생성한 namespace 간 통신 확인

root@devops:~# ip netns

uengine1 (id: 0)

root@devops:~# ip link delete dev veth0

root@devops:~# ip netns exec uengine1 ip addr

root@devops:~# ip netns add uengine2

root@devops:~# ip netns exec uengine2 ip link set dev lo up

root@devops:~# ip netns

uengine2
uengine1 (id: 0)

root@devops:~# ip netns exec uengine2 ip link

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

root@devops:~# ip link

root@devops:~# ip link add veth1 type veth peer name veth2

root@devops:~# ip link

root@devops:~# ip link set dev veth1 netns uengine1

root@devops:~# ip link set dev veth2 netns uengine2

root@devops:~# ip netns exec uengine1 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
veth1@if6 DOWN 9e:75:75:6f:03:82 <BROADCAST,MULTICAST>

root@devops:~# ip netns exec uengine2 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
veth2@if7 DOWN 4a:d8:94:37:f2:7e <BROADCAST,MULTICAST>

#IP 할당

root@devops:~# ip netns exec uengine1 ip addr add 192.168.0.100/24 dev veth1

root@devops:~# ip netns exec uengine2 ip addr add 192.168.0.200/24 dev veth2

root@devops:~# ip netns exec uengine1 ip link set dev veth1 up

root@devops:~# ip netns exec uengine2 ip link set dev veth2 up

root@devops:~# ip netns exec uengine2 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
veth2@if7 UP 4a:d8:94:37:f2:7e <BROADCAST,MULTICAST,UP,LOWER_UP>

root@devops:~# ip netns exec uengine1 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
veth1@if6 UP 9e:75:75:6f:03:82 <BROADCAST,MULTICAST,UP,LOWER_UP>

root@devops:~# ip netns ls

uengine2 (id: 1)
uengine1 (id: 0)

root@devops:~# ip netns exec uengine1 ping 192.168.0.200

PING 192.168.0.200 (192.168.0.200) 56(84) bytes of data.
64 bytes from 192.168.0.200: icmp_seq=1 ttl=64 time=0.098 ms
64 bytes from 192.168.0.200: icmp_seq=2 ttl=64 time=0.156 ms

root@devops:~# ip netns exec uengine1 ping 192.168.0.100

PING 192.168.0.100 (192.168.0.100) 56(84) bytes of data.
64 bytes from 192.168.0.100: icmp_seq=1 ttl=64 time=0.132 ms
64 bytes from 192.168.0.100: icmp_seq=2 ttl=64 time=0.051 ms

## 가상스위치를 만들어 2개의 namespace를 연결하고 default 도메인(로칼서버)과 통신

root@devops:~# ip netns exec uengine1 ip link delete dev veth1

root@devops:~# ip netns exec uengine2 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <loopback,up,lower_up></loopback,up,lower_up>

#브릿지 만들기

root@devops:~# ip link add br0 type bridge

root@devops:~# ip link

root@devops:~# ip link set br0 up

root@devops:~# ip link

# cable 만들기

root@devops:~# ip link add br1 type veth peer name veth1

root@devops:~# ip link add br2 type veth peer name veth2

root@devops:~# ip link

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 92:5c:0d:39:99:b2 brd ff:ff:ff:ff:ff:ff
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default
    link/ether 02:42:5b:86:7f:85 brd ff:ff:ff:ff:ff:ff
8: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/ether f2:ee:73:58:ab:13 brd ff:ff:ff:ff:ff:ff
9: veth1@br1: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 06:4d:76:28:dd:0d brd ff:ff:ff:ff:ff:ff
10: br1@veth1: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 56:d0:71:6b:d7:b6 brd ff:ff:ff:ff:ff:ff
11: veth2@br2: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 06:51:40:42:e2:2a brd ff:ff:ff:ff:ff:ff
12: br2@veth2: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 8a:2e:81:f4:1d:94 brd ff:ff:ff:ff:ff:ff

# 케이블 꽂기

root@devops:~# ip link set veth1 netns uengine1

root@devops:~# ip link set veth2 netns uengine2

root@devops:~# ip netns exec uengine1 ip addr add 192.168.0.101/24 dev veth1

root@devops:~# ip netns exec uengine2 ip addr add 192.168.0.102/24 dev veth2’

root@devops:~# ip netns exec uengine1

No command specified

root@devops:~# ip netns exec uengine1 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
veth1@if10 DOWN 06:4d:76:28:dd:0d <BROADCAST,MULTICAST>

root@devops:~# ip netns exec uengine1 ip link set dev veth1 up

root@devops:~# ip netns exec uengine2 ip link set dev veth2 up

root@devops:~# ip netns exec uengine2 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
veth2@if12 LOWERLAYERDOWN 06:51:40:42:e2:2a <NO-CARRIER,BROADCAST,MULTICAST,UP>

# 브릿지 디바이스 연결

root@devops:~# ip link set br1 master br0

root@devops:~# ip link set br2 master br0

root@devops:~# ip netns exec uengine1 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
veth1@if10 LOWERLAYERDOWN 06:4d:76:28:dd:0d <NO-CARRIER,BROADCAST,MULTICAST,UP>

# 브릿지 디바이스 활성화

root@devops:~# ip link set dev br1 up

root@devops:~# ip link set dev br2 up

root@devops:~# ip netns exec uengine2 ip -br link

lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
veth2@if12 UP 06:51:40:42:e2:2a <BROADCAST,MULTICAST,UP,LOWER_UP>

root@devops:~# ip netns exec uengine1 ping 192.168.0.102

PING 192.168.0.102 (192.168.0.102) 56(84) bytes of data.

root@devops:~# ip netns exec uengine1 ip addr

root@devops:~# ip netns exec uengine2 ip addr

root@devops:~# ip link

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether 92:5c:0d:39:99:b2 brd ff:ff:ff:ff:ff:ff
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default
    link/ether 02:42:5b:86:7f:85 brd ff:ff:ff:ff:ff:ff
8: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 56:d0:71:6b:d7:b6 brd ff:ff:ff:ff:ff:ff
10: br1@if9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UP mode DEFAULT group default qlen 1000
    link/ether 56:d0:71:6b:d7:b6 brd ff:ff:ff:ff:ff:ff link-netns uengine1
12: br2@if11: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UP mode DEFAULT group default qlen 1000
    link/ether 8a:2e:81:f4:1d:94 brd ff:ff:ff:ff:ff:ff link-netns uengine2

# 통신이 안될 경우 ip forward 정책 변경 : DROP -> ACCEPT

root@devops:~# iptables -L |grep FORWARD

Chain FORWARD (policy DROP)

root@devops:~# iptables --policy FORWARD ACCEPT

root@devops:~# ip netns exec uengine1 ping 192.168.0.102

PING 192.168.0.102 (192.168.0.102) 56(84) bytes of data.
64 bytes from 192.168.0.102: icmp_seq=1 ttl=64 time=0.185 ms
64 bytes from 192.168.0.102: icmp_seq=2 ttl=64 time=0.091 ms

root@devops:~# ip netns exec uengine2 ping 192.168.0.101

PING 192.168.0.101 (192.168.0.101) 56(84) bytes of data.
64 bytes from 192.168.0.101: icmp_seq=1 ttl=64 time=0.070 ms
64 bytes from 192.168.0.101: icmp_seq=2 ttl=64 time=0.072 ms

root@devops:~# ping 192.168.0.100

PING 192.168.0.100 (192.168.0.100) 56(84) bytes of data.
^C
--- 192.168.0.100 ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 1004ms

root@devops:~# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 92:5c:0d:39:99:b2 brd ff:ff:ff:ff:ff:ff
    inet 218.236.22.86/24 brd 218.236.22.255 scope global ens18
       valid_lft forever preferred_lft forever
    inet6 fe80::905c:dff:fe39:99b2/64 scope link
       valid_lft forever preferred_lft forever
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
    link/ether 02:42:5b:86:7f:85 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
8: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 56:d0:71:6b:d7:b6 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::f0ee:73ff:fe58:ab13/64 scope link
       valid_lft forever preferred_lft forever
10: br1@if9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UP group default qlen 1000
    link/ether 56:d0:71:6b:d7:b6 brd ff:ff:ff:ff:ff:ff link-netns uengine1
    inet6 fe80::54d0:71ff:fe6b:d7b6/64 scope link
       valid_lft forever preferred_lft forever
12: br2@if11: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UP group default qlen 1000
    link/ether 8a:2e:81:f4:1d:94 brd ff:ff:ff:ff:ff:ff link-netns uengine2
    inet6 fe80::882e:81ff:fef4:1d94/64 scope link
       valid_lft forever preferred_lft forever

root@devops:~# ping 192.168.0.101

PING 192.168.0.101 (192.168.0.101) 56(84) bytes of data.
^C
--- 192.168.0.101 ping statistics ---
1 packets transmitted, 0 received, 100% packet loss, time 0ms

root@devops:~# ip route

default via 218.236.22.254 dev ens18 proto static
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown
218.236.22.0/24 dev ens18 proto kernel scope link src 218.236.22.86

root@devops:~# route

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         _gateway        0.0.0.0         UG    0      0        0 ens18
172.17.0.0      0.0.0.0         255.255.0.0     U     0      0        0 docker0
218.236.22.0    0.0.0.0         255.255.255.0   U     0      0        0 ens18

# br0를 라우터로 활성화

root@devops:~# ip addr add 192.168.0.1/24 brd 192.168.0.255 dev br0

root@devops:~# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 92:5c:0d:39:99:b2 brd ff:ff:ff:ff:ff:ff
    inet 218.236.22.86/24 brd 218.236.22.255 scope global ens18
       valid_lft forever preferred_lft forever
    inet6 fe80::905c:dff:fe39:99b2/64 scope link
       valid_lft forever preferred_lft forever
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
    link/ether 02:42:5b:86:7f:85 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
8: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 56:d0:71:6b:d7:b6 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.1/24 brd 192.168.0.255 scope global br0
       valid_lft forever preferred_lft forever
    inet6 fe80::f0ee:73ff:fe58:ab13/64 scope link
       valid_lft forever preferred_lft forever
10: br1@if9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UP group default qlen 1000
    link/ether 56:d0:71:6b:d7:b6 brd ff:ff:ff:ff:ff:ff link-netns uengine1
    inet6 fe80::54d0:71ff:fe6b:d7b6/64 scope link
       valid_lft forever preferred_lft forever
12: br2@if11: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UP group default qlen 1000
    link/ether 8a:2e:81:f4:1d:94 brd ff:ff:ff:ff:ff:ff link-netns uengine2
    inet6 fe80::882e:81ff:fef4:1d94/64 scope link
       valid_lft forever preferred_lft forever

root@devops:~# ip addr show br0

8: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 56:d0:71:6b:d7:b6 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.1/24 brd 192.168.0.255 scope global br0
       valid_lft forever preferred_lft forever
    inet6 fe80::f0ee:73ff:fe58:ab13/64 scope link
       valid_lft forever preferred_lft forever

root@devops:~# route

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         _gateway        0.0.0.0         UG    0      0        0 ens18
172.17.0.0      0.0.0.0         255.255.0.0     U     0      0        0 docker0
192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0 br0
218.236.22.0    0.0.0.0         255.255.255.0   U     0      0        0 ens18

root@devops:~# ping 192.168.0.101

PING 192.168.0.101 (192.168.0.101) 56(84) bytes of data.
64 bytes from 192.168.0.101: icmp_seq=1 ttl=64 time=0.341 ms
64 bytes from 192.168.0.101: icmp_seq=2 ttl=64 time=0.071 ms

root@devops:~# ping 192.168.0.102

PING 192.168.0.102 (192.168.0.102) 56(84) bytes of data.
64 bytes from 192.168.0.102: icmp_seq=1 ttl=64 time=0.197 ms
64 bytes from 192.168.0.102: icmp_seq=2 ttl=64 time=0.064 ms

root@devops:~# ip addr

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 92:5c:0d:39:99:b2 brd ff:ff:ff:ff:ff:ff
    inet 218.236.22.86/24 brd 218.236.22.255 scope global ens18
       valid_lft forever preferred_lft forever
    inet6 fe80::905c:dff:fe39:99b2/64 scope link
       valid_lft forever preferred_lft forever
3: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
    link/ether 02:42:5b:86:7f:85 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
8: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 56:d0:71:6b:d7:b6 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.1/24 brd 192.168.0.255 scope global br0
       valid_lft forever preferred_lft forever
    inet6 fe80::f0ee:73ff:fe58:ab13/64 scope link
       valid_lft forever preferred_lft forever
10: br1@if9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UP group default qlen 1000
    link/ether 56:d0:71:6b:d7:b6 brd ff:ff:ff:ff:ff:ff link-netns uengine1
    inet6 fe80::54d0:71ff:fe6b:d7b6/64 scope link
       valid_lft forever preferred_lft forever
12: br2@if11: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UP group default qlen 1000
    link/ether 8a:2e:81:f4:1d:94 brd ff:ff:ff:ff:ff:ff link-netns uengine2
    inet6 fe80::882e:81ff:fef4:1d94/64 scope link
       valid_lft forever preferred_lft forever

root@devops:~# ip netns exec uengine1 ping 10.0.0.4

ping: connect: Network is unreachable

root@devops:~# ip netns exec uengine1 ping 192.168.0.1

PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data.
64 bytes from 192.168.0.1: icmp_seq=1 ttl=64 time=0.063 ms
64 bytes from 192.168.0.1: icmp_seq=2 ttl=64 time=0.063 ms

root@devops:~# ip netns exec uengine1 route

Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 veth1

## 만들어진 2개의 namespace를 외부와 통신

root@devops:~# ip netns exec uengine1 ping 8.8.8.8

ping: connect: Network is unreachable

root@devops:~# ip addr show eth0

Device "eth0" does not exist.

root@devops:~# ip netns exec uengine1 ping 10.0.0.4

ping: connect: Network is unreachable

root@devops:~# ip route

default via 218.236.22.254 dev ens18 proto static
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown
192.168.0.0/24 dev br0 proto kernel scope link src 192.168.0.1
218.236.22.0/24 dev ens18 proto kernel scope link src 218.236.22.86

root@devops:~# ip netns exec uengine1 ip route

192.168.0.0/24 dev veth1 proto kernel scope link src 192.168.0.101

# namespace에서 br0를 라우터로 등록

root@devops:~# ip netns exec uengine1 ip route add default via 192.168.0.1

root@devops:~# ip netns exec uengine2 ip route add default via 192.168.0.1

root@devops:~# ip netns exec uengine ip route

Cannot open network namespace "uengine": No such file or directory

root@devops:~# ip netns exec uengine1 ip route

default via 192.168.0.1 dev veth1
192.168.0.0/24 dev veth1 proto kernel scope link src 192.168.0.101

root@devops:~# ip netns exec uengine1 ping 10.0.0.4

PING 10.0.0.4 (10.0.0.4) 56(84) bytes of data.

root@devops:~# ip netns exec uengine1 ping 8.8.8.8

PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.

root@devops:~# sysctl -a|grep forward

net.ipv4.conf.all.bc_forwarding = 0
net.ipv4.conf.all.forwarding = 1
net.ipv4.conf.all.mc_forwarding = 0
net.ipv4.conf.br0.bc_forwarding = 0
net.ipv4.conf.br0.forwarding = 1
net.ipv4.conf.br0.mc_forwarding = 0
net.ipv4.conf.br1.bc_forwarding = 0
net.ipv4.conf.br1.forwarding = 1
net.ipv4.conf.br1.mc_forwarding = 0
net.ipv4.conf.br2.bc_forwarding = 0
net.ipv4.conf.br2.forwarding = 1
net.ipv4.conf.br2.mc_forwarding = 0
net.ipv4.conf.default.bc_forwarding = 0
net.ipv4.conf.default.forwarding = 1
net.ipv4.conf.default.mc_forwarding = 0
net.ipv4.conf.docker0.bc_forwarding = 0
net.ipv4.conf.docker0.forwarding = 1
net.ipv4.conf.docker0.mc_forwarding = 0
net.ipv4.conf.ens18.bc_forwarding = 0
net.ipv4.conf.ens18.forwarding = 1
net.ipv4.conf.ens18.mc_forwarding = 0
net.ipv4.conf.lo.bc_forwarding = 0
net.ipv4.conf.lo.forwarding = 1
net.ipv4.conf.lo.mc_forwarding = 0
net.ipv4.ip_forward = 1
net.ipv4.ip_forward_update_priority = 1
net.ipv4.ip_forward_use_pmtu = 0
net.ipv6.conf.all.forwarding = 0
net.ipv6.conf.all.mc_forwarding = 0
net.ipv6.conf.br0.forwarding = 0
net.ipv6.conf.br0.mc_forwarding = 0
net.ipv6.conf.br1.forwarding = 0
net.ipv6.conf.br1.mc_forwarding = 0
net.ipv6.conf.br2.forwarding = 0
net.ipv6.conf.br2.mc_forwarding = 0
net.ipv6.conf.default.forwarding = 0
net.ipv6.conf.default.mc_forwarding = 0
net.ipv6.conf.docker0.forwarding = 0
net.ipv6.conf.docker0.mc_forwarding = 0
net.ipv6.conf.ens18.forwarding = 0
net.ipv6.conf.ens18.mc_forwarding = 0
net.ipv6.conf.lo.forwarding = 0
net.ipv6.conf.lo.mc_forwarding = 0

# namespace에서 외부IP 통신을 위한 namespace 대역 masquerade 적용 1/2

root@devops:~# sysctl -w net.ipv4.ip_forward=1

net.ipv4.ip_forward = 1

# namespace에서 외부IP 통신을 위한 namespace 대역 masquerade 적용 2/2

root@devops:~# iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -j MASQUERADE

root@devops:~# iptables -L

Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
DOCKER-USER  all  --  anywhere             anywhere
DOCKER-ISOLATION-STAGE-1  all  --  anywhere             anywhere
ACCEPT     all  --  anywhere             anywhere             ctstate RELATED,ESTABLISHED
DOCKER     all  --  anywhere             anywhere
ACCEPT     all  --  anywhere             anywhere
ACCEPT     all  --  anywhere             anywhere

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Chain DOCKER (1 references)
target     prot opt source               destination

Chain DOCKER-ISOLATION-STAGE-1 (1 references)
target     prot opt source               destination
DOCKER-ISOLATION-STAGE-2  all  --  anywhere             anywhere
RETURN     all  --  anywhere             anywhere

Chain DOCKER-ISOLATION-STAGE-2 (1 references)
target     prot opt source               destination
DROP       all  --  anywhere             anywhere
RETURN     all  --  anywhere             anywhere

Chain DOCKER-USER (1 references)
target     prot opt source               destination
RETURN     all  --  anywhere             anywhere

root@devops:~# ip netns exec uengine1 ping 8.8.8.8

PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=56 time=76.7 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=56 time=76.5 ms

root@devops:~# ip netns exec uengine1 curl google.com

curl: (6) Could not resolve host: google.com

root@devops:~# mkdir -p /etc/netns/uengine1/

# namespace 외부 DNS 통신 확인

root@devops:~# echo 'nameserver 8.8.8.8' > /etc/netns/uengine1/resolv.conf

root@devops:~# ip netns exec uengine1 curl google.com

<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
here.
</BODY></HTML>

root@devops:~# mkdir -p /etc/netns/uengine2

root@devops:~# echo 'nameserver 8.8.8.8' > /etc/netns/uengine2/resolv.conf

root@devops:~# ip netns exec uengine2 curl google.com

<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
here.
</BODY></HTML>

## 지우는 명령어

Ip link delete br0

Ip link delete uengine1

# 네임스페이스 지우는 명령어

ip netns delete uengine1

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