来源:分布式实验室
使用容器总是感觉像使用魔法一样。对于那些理解底层原理的人来说容器很好用,但是对于不理解的人来说就是个噩梦。很幸运的是,我们已经研究容器技术很久了,甚至成功揭秘容器只是隔离并受限的Linux进程,运行容器并不需要镜像,以及另一个方面,构建镜像需要运行一些容器。现在是时候解决容器网络问题了。或者更准确地说,单主机容器网络问题。本文会回答这些问题:
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如何虚拟化网络资源,让容器认为自己拥有独占网络?
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如何让容器们和平共处,之间不会互相干扰,并且能够互相通信?
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从容器内部如何访问外部世界(比如,互联网)?
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从外部世界如何访问某台机器上的容器呢(比如,端口发布)?
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网络命名空间(namespace)
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虚拟Ethernet设备(veth)
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虚拟网络交换机(网桥)
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IP路由和网络地址翻译(NAT)
前提条件
任意Linux发行版都可以。本文的所有例子都是在vagrant CentOS 8的虚拟机上执行的:
$ vagrant init centos/8
$ vagrant up
$ vagrant ssh
[vagrant@localhost ~]$ uname -a
Linux localhost.localdomain 4.18.0-147.3.1.el8_1.x86_64
network命名空间隔离容器
Linux网络栈包括哪些部分?显然,是一系列网络设备。还有别的吗?可能还包括一系列的路由规则。并且不要忘记,netfilter hook,包括由iptables规则定义的。我们可以快速创建一个并不复杂的脚本inspect-net-stack.sh:
#!/usr/bin/env bash
echo "> Network devices"
ip link
echo -e "\n> Route table"
ip route
echo -e "\n> Iptables rules"
iptables --list-rules
$ sudo iptables -N ROOT_NS
这之后,在机器上执行上面的脚本,输出如下:$ sudo ./inspect-net-stack.sh
> Network devices
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: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000 link/ether 52:54:00:e3:27:77 brd ff:ff:ff:ff:ff:ff
> Route table
default via 10.0.2.2 dev eth0 proto dhcp metric 100
10.0.2.0/24 dev eth0 proto kernel scope link src 10.0.2.15 metric 100
> Iptables rules
-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-N ROOT_NS
$ sudo ip netns add netns0
$ ip netns
netns0
$ sudo nsenter --net=/var/run/netns/netns0 bash
# 新建的bash进程在netns0里
$ sudo ./inspect-net-stack.sh
> Network devices 1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> Route table
> Iptables rules
-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
使用虚拟的Ethernet设备(veth)将容器连接到主机上
如果我们无法和某个专有的网络栈通信,那么它看上去就没什么用。幸运的是,Linux提供了好用的工具——虚拟Ethernet设备。从man veth可以看到,“veth设备是虚拟Ethernet设备。他们可以作为网络命名空间之间的通道(tunnel),从而创建连接到另一个命名空间里的物理网络设备的桥梁,但是也可以作为独立的网络设备使用。”虚拟Ethernet设备通常都成对出现。不用担心,先看一下创建的脚本:
$ sudo ip link add veth0 type veth peer name ceth0
用这条简单的命令,我们就可以创建一对互联的虚拟Ethernet设备。默认选择了veth0和ceth0这两个名称。$ 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: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:e3:27:77 brd ff:ff:ff:ff:ff:ff
5: ceth0@veth0: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
link/ether 66:2d:24:e3:49:3f brd ff:ff:ff:ff:ff:ff
6: veth0@ceth0: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
link/ether 96:e8:de:1d:22:e0 brd ff:ff:ff:ff:ff:ff
$ sudo ip link set ceth0 netns netns0
# 列出所有设备,可以看到ceth0已经从root栈里消失了
$ 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: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:e3:27:77 brd ff:ff:ff:ff:ff:ff
6: veth0@if5: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
link/ether 96:e8:de:1d:22:e0 brd ff:ff:ff:ff:ff:ff link-netns netns0
$ sudo ip link set veth0 up
$ sudo ip addr add 172.18.0.11/16 dev veth0
$ sudo nsenter --net=/var/run/netns/netns0
$ ip link set lo up
$ ip link set ceth0 up
$ ip addr add 172.18.0.10/16 dev ceth0
$ 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
5: ceth0@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
link/ether 66:2d:24:e3:49:3f brd ff:ff:ff:ff:ff:ff link-netnsid 0
检查连通性:
# 在netns0里ping root的 veth0
$ ping -c 2 172.18.0.11
PING 172.18.0.11 (172.18.0.11) 56(84) bytes of data.
64 bytes from 172.18.0.11: icmp_seq=1 ttl=64 time=0.038 ms
64 bytes from 172.18.0.11: icmp_seq=2 ttl=64 time=0.040 ms
--- 172.18.0.11 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 58ms
rtt min/avg/max/mdev = 0.038/0.039/0.040/0.001 ms
# 离开 netns0
$ exit
# 在root命名空间里ping ceth0
$ ping -c 2 172.18.0.10
PING 172.18.0.10 (172.18.0.10) 56(84) bytes of data.
64 bytes from 172.18.0.10: icmp_seq=1 ttl=64 time=0.073 ms
64 bytes from 172.18.0.10: icmp_seq=2 ttl=64 time=0.046 ms
--- 172.18.0.10 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 3ms
rtt min/avg/max/mdev = 0.046/0.059/0.073/0.015 ms
# 在 root 命名空间
$ ip addr show dev eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether 52:54:00:e3:27:77 brd ff:ff:ff:ff:ff:ff
inet 10.0.2.15/24 brd 10.0.2.255 scope global dynamic noprefixroute eth0
valid_lft 84057sec preferred_lft 84057sec
inet6 fe80::5054:ff:fee3:2777/64 scope link
valid_lft forever preferred_lft forever
# 记住这里IP是10.0.2.15
$ sudo nsenter --net=/var/run/netns/netns0
# 尝试ping主机的eth0
$ ping 10.0.2.15
connect: Network is unreachable
# 尝试连接外网
$ ping 8.8.8.8
connect: Network is unreachable
# 在netns0命名空间:
$ ip route
172.18.0.0/16 dev ceth0 proto kernel scope link src 172.18.0.10
$ ip route
# ... 忽略无关行 ...
172.18.0.0/16 dev veth0 proto kernel scope link src 172.18.0.11这里,就可以回答第一个问题了。我们了解了如何隔离,虚拟化并且连接Linux网络栈。
使用虚拟网络switch(网桥)连接容器
容器化思想的驱动力是高效的资源共享。所以,一台机器上只运行一个容器并不常见。相反,最终目标是尽可能地在共享的环境上运行更多的隔离进程。因此,如果按照上述veth方案,在同一台主机上放置多个容器的话会发生什么呢?让我们尝试添加第二个容器。
# 从 root 命名空间
$ sudo ip netns add netns1
$ sudo ip link add veth1 type veth peer name ceth1
$ sudo ip link set ceth1 netns netns1
$ sudo ip link set veth1 up
$ sudo ip addr add 172.18.0.21/16 dev veth1
$ sudo nsenter --net=/var/run/netns/netns1
$ ip link set lo up
$ ip link set ceth1 up
$ ip addr add 172.18.0.20/16 dev ceth1
# 从netns1无法连通root 命名空间!
$ ping -c 2 172.18.0.21
PING 172.18.0.21 (172.18.0.21) 56(84) bytes of data.
From 172.18.0.20 icmp_seq=1 Destination Host Unreachable
From 172.18.0.20 icmp_seq=2 Destination Host Unreachable
--- 172.18.0.21 ping statistics ---
2 packets transmitted, 0 received, +2 errors, 100% packet loss, time 55ms pipe 2
# 但是路由是存在的!
$ ip route
172.18.0.0/16 dev ceth1 proto kernel scope link src 172.18.0.20
# 离开 `netns1`
$ exit
# 从 root 命名空间无法连通`netns1`
$ ping -c 2 172.18.0.20
PING 172.18.0.20 (172.18.0.20) 56(84) bytes of data.
From 172.18.0.11 icmp_seq=1 Destination Host Unreachable
From 172.18.0.11 icmp_seq=2 Destination Host Unreachable
--- 172.18.0.20 ping statistics ---
2 packets transmitted, 0 received, +2 errors, 100% packet loss, time 23ms pipe 2
# 从netns0可以连通`veth1`
$ sudo nsenter --net=/var/run/netns/netns0
$ ping -c 2 172.18.0.21
PING 172.18.0.21 (172.18.0.21) 56(84) bytes of data.
64 bytes from 172.18.0.21: icmp_seq=1 ttl=64 time=0.037 ms
64 bytes from 172.18.0.21: icmp_seq=2 ttl=64 time=0.046 ms
--- 172.18.0.21 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 33ms
rtt min/avg/max/mdev = 0.037/0.041/0.046/0.007 ms
# 但是仍然无法连通netns1
$ ping -c 2 172.18.0.20
PING 172.18.0.20 (172.18.0.20) 56(84) bytes of data.
From 172.18.0.10 icmp_seq=1 Destination Host Unreachable
From 172.18.0.10 icmp_seq=2 Destination Host Unreachable
--- 172.18.0.20 ping statistics ---
2 packets transmitted, 0 received, +2 errors, 100% packet loss, time 63ms pipe 2
$ ip route
# ... 忽略无关行... #
172.18.0.0/16 dev veth0 proto kernel scope link src 172.18.0.11
172.18.0.0/16 dev veth1 proto kernel scope link src 172.18.0.21
$ sudo ip netns delete netns0
$ sudo ip netns delete netns1
$ sudo ip link delete veth0
$ sudo ip link delete ceth0
$ sudo ip link delete veth1
$ sudo ip link delete ceth1
$ sudo ip netns add netns0
$ sudo ip link add veth0 type veth peer name ceth0
$ sudo ip link set veth0 up
$ sudo ip link set ceth0 netns netns0
$ sudo nsenter --net=/var/run/netns/netns0
$ ip link set lo up
$ ip link set ceth0 up
$ ip addr add 172.18.0.10/16 dev ceth0
$ exit
$ sudo ip netns add netns1
$ sudo ip link add veth1 type veth peer name ceth1
$ sudo ip link set veth1 up
$ sudo ip link set ceth1 netns netns1
$ sudo nsenter --net=/var/run/netns/netns1
$ ip link set lo up
$ ip link set ceth1 up
$ ip addr add 172.18.0.20/16 dev ceth1
$ exit
$ ip route
default via 10.0.2.2 dev eth0 proto dhcp metric 100
10.0.2.0/24 dev eth0 proto kernel scope link src 10.0.2.15 metric 100
$ sudo ip link add br0 type bridge
$ sudo ip link set br0 up
$ sudo ip link set veth0 master br0
$ sudo ip link set veth1 master br0
检查容器间的连通性:
$ sudo nsenter --net=/var/run/netns/netns0
$ ping -c 2 172.18.0.20
PING 172.18.0.20 (172.18.0.20) 56(84) bytes of data.
64 bytes from 172.18.0.20: icmp_seq=1 ttl=64 time=0.259 ms
64 bytes from 172.18.0.20: icmp_seq=2 ttl=64 time=0.051 ms
--- 172.18.0.20 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 2ms
rtt min/avg/max/mdev = 0.051/0.155/0.259/0.104 ms
$ sudo nsenter --net=/var/run/netns/netns1
$ ping -c 2 172.18.0.10
PING 172.18.0.10 (172.18.0.10) 56(84) bytes of data.
64 bytes from 172.18.0.10: icmp_seq=1 ttl=64 time=0.037 ms
64 bytes from 172.18.0.10: icmp_seq=2 ttl=64 time=0.089 ms
--- 172.18.0.10 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 36ms
rtt min/avg/max/mdev = 0.037/0.063/0.089/0.026 ms
$ sudo nsenter --net=/var/run/netns/netns0
$ ip neigh
172.18.0.20 dev ceth0 lladdr 6e:9c:ae:02:60:de STALE
$ exit
$ sudo nsenter --net=/var/run/netns/netns1
$ ip neigh
172.18.0.10 dev ceth1 lladdr 66:f3:8c:75:09:29 STALE
$ exit
连接外部世界(IP路由和地址伪装(masquerading))
容器间可以通信。但是它们能和主机,比如root命名空间,通信吗?
$ sudo nsenter --net=/var/run/netns/netns0
$ ping 10.0.2.15 # eth0 address
connect: Network is unreachable
$ ip route
172.18.0.0/16 dev ceth0 proto kernel scope link src 172.18.0.10
$ ping -c 2 172.18.0.10
PING 172.18.0.10 (172.18.0.10) 56(84) bytes of data.
From 213.51.1.123 icmp_seq=1 Destination Net Unreachable
From 213.51.1.123 icmp_seq=2 Destination Net Unreachable
--- 172.18.0.10 ping statistics ---
2 packets transmitted, 0 received, +2 errors, 100% packet loss, time 3ms
$ ping -c 2 172.18.0.20
PING 172.18.0.20 (172.18.0.20) 56(84) bytes of data.
From 213.51.1.123 icmp_seq=1 Destination Net Unreachable
From 213.51.1.123 icmp_seq=2 Destination Net Unreachable
--- 172.18.0.20 ping statistics ---
2 packets transmitted, 0 received, +2 errors, 100% packet loss, time 3ms要建立root和容器命名空间的连通性,我们需要给网桥网络接口分配IP地址:
$ sudo ip addr add 172.18.0.1/16 dev br0
一旦给网桥网络接口分配了IP地址,在主机的路由表里就会多一条路由:$ ip route
# ...忽略无关行 ...
172.18.0.0/16 dev br0 proto kernel scope link src 172.18.0.1
$ ping -c 2 172.18.0.10
PING 172.18.0.10 (172.18.0.10) 56(84) bytes of data.
64 bytes from 172.18.0.10: icmp_seq=1 ttl=64 time=0.036 ms
64 bytes from 172.18.0.10: icmp_seq=2 ttl=64 time=0.049 ms
--- 172.18.0.10 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 11ms
rtt min/avg/max/mdev = 0.036/0.042/0.049/0.009 ms
$ ping -c 2 172.18.0.20
PING 172.18.0.20 (172.18.0.20) 56(84) bytes of data.
64 bytes from 172.18.0.20: icmp_seq=1 ttl=64 time=0.059 ms
64 bytes from 172.18.0.20: icmp_seq=2 ttl=64 time=0.056 ms
--- 172.18.0.20 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 4ms
rtt min/avg/max/mdev = 0.056/0.057/0.059/0.007 ms
$ sudo nsenter --net=/var/run/netns/netns0
$ ip route add default via 172.18.0.1
$ ping -c 2 10.0.2.15
PING 10.0.2.15 (10.0.2.15) 56(84) bytes of data.
64 bytes from 10.0.2.15: icmp_seq=1 ttl=64 time=0.036 ms
64 bytes from 10.0.2.15: icmp_seq=2 ttl=64 time=0.053 ms
--- 10.0.2.15 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 14ms
rtt min/avg/max/mdev = 0.036/0.044/0.053/0.010 ms
# 为`netns1`也做上述配置
# 在 root 命名空间
sudo bash -c 'echo 1 > /proc/sys/net/ipv4/ip_forward'
$ sudo nsenter --net=/var/run/netns/netns0
$ ping 8.8.8.8
# hung住了...
$ sudo iptables -t nat -A POSTROUTING -s 172.18.0.0/16 ! -o br0 -j MASQUERADE
命令非常简单。在nat表里添加了一条POSTROUTING chain的新路由,会替换伪装所有源于172.18.0.0/16网络的包,但是不通过网桥接口。检查连通性:$ sudo nsenter --net=/var/run/netns/netns0$ ping -c 2 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=61 time=43.2 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=61 time=36.8 ms
--- 8.8.8.8 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 2ms
rtt min/avg/max/mdev = 36.815/40.008/43.202/3.199 ms要知道这里我们用的默认策略——允许所有流量,这在真实的环境里是非常危险的。主机的默认iptables策略是ACCEPT:
sudo iptables -S
-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
$ sudo iptables -t filter --list-rules
-P INPUT ACCEPT
-P FORWARD DROP
-P OUTPUT ACCEPT
-N DOCKER
-N DOCKER-ISOLATION-STAGE-1
-N DOCKER-ISOLATION-STAGE-2
-N DOCKER-USER
-A FORWARD -j DOCKER-USER
-A FORWARD -j DOCKER-ISOLATION-STAGE-1
-A FORWARD -o docker0 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -o docker0 -j DOCKER
-A FORWARD -i docker0 ! -o docker0 -j ACCEPT
-A FORWARD -i docker0 -o docker0 -j ACCEPT
-A DOCKER -d 172.17.0.2/32 ! -i docker0 -o docker0 -p tcp -m tcp --dport 5000 -j ACCEPT
-A DOCKER-ISOLATION-STAGE-1 -i docker0 ! -o docker0 -j DOCKER-ISOLATION-STAGE-2
-A DOCKER-ISOLATION-STAGE-1 -j RETURN
-A DOCKER-ISOLATION-STAGE-2 -o docker0 -j DROP
-A DOCKER-ISOLATION-STAGE-2 -j RETURN
-A DOCKER-USER -j RETURN
$ sudo iptables -t nat --list-rules
-P PREROUTING ACCEPT
-P INPUT ACCEPT
-P POSTROUTING ACCEPT
-P OUTPUT ACCEPT
-N DOCKER
-A PREROUTING -m addrtype --dst-type LOCAL -j DOCKER
-A POSTROUTING -s 172.17.0.0/16 ! -o docker0 -j MASQUERADE
-A POSTROUTING -s 172.17.0.2/32 -d 172.17.0.2/32 -p tcp -m tcp --dport 5000 -j MASQUERADE
-A OUTPUT ! -d 127.0.0.0/8 -m addrtype --dst-type LOCAL -j DOCKER
-A DOCKER -i docker0 -j RETURN
-A DOCKER ! -i docker0 -p tcp -m tcp --dport 5005 -j DNAT --to-destination 172.17.0.2:5000
$ sudo iptables -t mangle --list-rules
-P PREROUTING ACCEPT
-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-P POSTROUTING ACCEPT
$ sudo iptables -t raw --list-rules
-P PREROUTING ACCEPT
-P OUTPUT ACCEPT
大家都知道可以将容器端口发布给一些(或者所有)主机的接口。但是端口发布到底是什么意思呢?假设容器内运行着服务器:
$ sudo nsenter --net=/var/run/netns/netns0
$ python3 -m http.server --bind 172.18.0.10 5000
# 从 root 命名空间
$ curl 172.18.0.10:5000
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
# ... 忽略无关行 ...
$ curl 10.0.2.15:5000
curl: (7) Failed to connect to 10.0.2.15 port 5000: Connection refused
# 外部流量
sudo iptables -t nat -A PREROUTING -d 10.0.2.15 -p tcp -m tcp --dport 5000 -j DNAT --to-destination 172.18.0.10:5000
# 本地流量 (因为它没有通过 PREROUTING chain)
sudo iptables -t nat -A OUTPUT -d 10.0.2.15 -p tcp -m tcp --dport 5000 -j DNAT --to-destination 172.18.0.10:5000
sudo modprobe br_netfilter
测试:curl 10.0.2.15:5000
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
# ... 忽略无关行 ...
我们可以怎么使用这些知识呢?比如,可以试着理解Docker网络模式[1]。从--network host模式开始。试着比较一下命令ip link和sudo docker run -it --rm --network host alpine ip link的输出。它们几乎一样!在host模式下,Docker简单地没有使用网络命名空间隔离,容器就在root网络命名空间里工作,并且和主机共享网络栈。下一个模式是--network none。sudo docker run -it --rm --network host alpine ip link的输出只有一个loopback网络接口。这和之前创建的网络命名空间,没有添加veth设备前很相似。最后是--network bridge(默认)模式。这正是我们前文尝试创建的模式。大家可以试试ip 和iptables命令,分别从主机和容器的角度观察一下网络栈。
rootless容器和网络
Podman容器管理器的一个很好的特性是关注于rootless容器。但是,你可能注意到,本文使用了很多sudo命令。说明,没有root权限无法配置网络。Podman在root网络上的方案[2]和Docker非常相似。但是在rootless容器上,Podman使用了slirp4netns[3]项目:从Linux 3.8开始,非特权用户可以创建user_namespaces(7)的同时创建network_namespaces(7)。但是,非特权网络命名空间并不是很有用,因为在主机和网络命名空间之间创建veth(4)仍然需要root权限
slirp4netns可以用完全非特权的方式将网络命名空间连接到Internet上,通过网络命名空间里的一个TAP设备连接到用户态的TCP/IP栈(slirp)。
rootless网络是很有限的:“从技术上说,容器本身没有IP地址,因为没有root权限,无法实现网络设备的关联。另外,从rootless容器ping是不会工作的,因为它缺少CAP_NET_RAW安全能力,而这是ping命令必需的。”但是它仍然比完全没有连接要好。结论
本文介绍的组织容器网络的方案仅仅是可能方案的一种(可能是最为广泛使用的一种)。还有很多别的方式,由官方或者第三方插件实现,但是所有这些方案都严重依赖于Linux网络虚拟化技术[4]。因此,容器化可以认为是一种虚拟化技术。相关链接:
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https://docs.docker.com/network/#network-drivers
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https://www.redhat.com/sysadmin/container-networking-podman
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https://github.com/rootless-containers/slirp4netns
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https://developers.redhat.com/blog/2018/10/22/introduction-to-linux-interfaces-for-virtual-networking/
原文链接:https://iximiuz.com/en/posts/container-networking-is-simple