強制新程序使用特定的網路介面（使用 netns/network 命名空間）

我在 Ubuntu 20.04 機器上有許多可用的介面。除其他外 enx0c5b8f279a64，usb0後者被用作預設值。我想確保在終端中啟動的特定程序將僅使用其中一個介面（enx0c5b8f279a64即使另一個介面是預設介面）。如果該程序啟動並且所選 enx0c5b8f279a64 介面已關閉，則它甚至不應該嘗試使用任何其他介面作為備份（就好像從該程序的角度來看甚至不存在其他介面）。

我認為這ip netns是要走的路，但我無法實施任何可行的解決方案。我已經嘗試過https://superuser.com/a/750412但是Destination Host Unreachable如果我嘗試 ping我會得到8.8.8.8:(

輸出的相關部分ip a s：

9: enx0c5b8f279a64: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 12:12:12:12:12:12 brd ff:ff:ff:ff:ff:ff
    inet 192.168.7.100/24 brd 192.168.7.255 scope global dynamic noprefixroute enx0c5b8f279a64
       valid_lft 84611sec preferred_lft 84611sec
    inet6 2323::2323:2323:2323:2323/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
10: usb0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 1000
    link/ether 34:34:34:34:34:34 brd ff:ff:ff:ff:ff:ff
    inet 192.168.42.**47**/24 brd 192.168.42.255 scope global dynamic noprefixroute usb0
       valid_lft 1858sec preferred_lft 1858sec
    inet6 4545:454:545:4545:454:5454:5454:5454/64 scope global temporary deprecated dynamic 
       valid_lft 2461sec preferred_lft 0sec
    inet6 5656:565:656:5656:5656:5656:5656:5656/64 scope global deprecated dynamic mngtmpaddr noprefixroute 
       valid_lft 2461sec preferred_lft 0sec
    inet6 6767::6767:6767:6767:6767/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

和路由表：

route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.7.1     0.0.0.0         UG    100    0        0 enx0c5b8f279a64
0.0.0.0         192.168.42.129  0.0.0.0         UG    101    0        0 usb0
192.168.7.0     0.0.0.0         255.255.255.0   U     100    0        0 enx0c5b8f279a64
192.168.42.0    0.0.0.0         255.255.255.0   U     101    0        0 usb0

到目前為止，我嘗試過的所有解決方案都以類似的方式開始：

# create namespace
sudo ip netns add nspace0
# create link
sudo ip link add veth0 type veth peer name veth1
# move link
sudo ip link set veth1 netns nspace0

# DO SOME MAGIC 
# (none of the solutions that I have tried to adapt here worked for me so far).
...

# run process in namespace (here I use curl as an example) 
sudo ip netns exec nspace0 curl ifconfig.me/ip

但問題是MAGIC部分。我已經看到了許多使用網橋和其他 IP 轉發解決方案的方法。不幸的是，到目前為止，這些都沒有對我有用，而且我並不精通網路，無法診斷和修復。

它似乎適用於以下腳本。我最初的問題中沒有的一個額外功能是如何將介面保留在主命名空間和新命名空間中（但我稍後會處理）。以下是基於以下提供的資訊的描述性解決方案：here、here、here、here、here和here。

# Save default settings to files for a handy reference
ip addr > log_000.ip_addr.txt
ip link > log_000.ip_link.txt
ip route > log_000.ip_route.txt
route -n > log_000.route_n.txt

# Interfaces
INTERFACE_0="usb0"
INTERFACE_1="enx0c5b8f279a64"

# Collect information on current configuration
PUBL_IP=$(curl --silent ifconfig.me/ip)
INTERFACE_0_PUBL_IP=$(curl --silent --interface ${INTERFACE_0} ifconfig.me/ip)
INTERFACE_1_PUBL_IP=$(curl --silent --interface ${INTERFACE_1} ifconfig.me/ip)

INTERFACE_0_PRIV_IP=$(ip a show ${INTERFACE_0} | awk '/inet / {print $2}')
INTERFACE_1_PRIV_IP=$(ip a show ${INTERFACE_1} | awk '/inet / {print $2}')

INTERFACE_0_GATE=$(ip route show dev ${INTERFACE_0} | awk '/default via/ {print $3}')
INTERFACE_1_GATE=$(ip route show dev ${INTERFACE_1} | awk '/default via/ {print $3}')

echo "" > log_001.IPs.txt
echo "PUBL_IP: ${PUBL_IP}"                          >> log_001.IPs.txt
echo "============================================" >> log_001.IPs.txt
echo "INTERFACE_0_PUBL_IP: ${INTERFACE_0_PUBL_IP}"  >> log_001.IPs.txt
echo "INTERFACE_0_PRIV_IP: ${INTERFACE_0_PRIV_IP}"  >> log_001.IPs.txt
echo "INTERFACE_0_GATE: ${INTERFACE_0_GATE}"        >> log_001.IPs.txt
echo "============================================" >> log_001.IPs.txt
echo "INTERFACE_1_PUBL_IP: ${INTERFACE_1_PUBL_IP}"  >> log_001.IPs.txt
echo "INTERFACE_1_PRIV_IP: ${INTERFACE_1_PRIV_IP}"  >> log_001.IPs.txt
echo "INTERFACE_1_GATE: ${INTERFACE_1_GATE}"        >> log_001.IPs.txt
cat log_001.IPs.txt

NAMESPACE_1="ns1"

# SETUP: Create new namespace.
sudo ip netns add ${NAMESPACE_1}

# CHECKUP: Verify that the namesapce was created.
sudo ip netns list

# CHECKUP: List interfaces in the main and new namespace
ip addr show
sudo ip netns exec ${NAMESPACE_1} ip addr show

# SETUP: Link (move) interface to namespace.
# NB this interface will not be availabie in the main (default) namespace anymoe.
sudo ip link set ${INTERFACE_1} netns ${NAMESPACE_1}

# CHECKUP: verify that the interface was moved from main to new namespace.
ip addr show
sudo ip netns exec ${NAMESPACE_1} ip addr show

# SETUP: Set interface IP address in new namespace and bring it up.
# TODO: Check it the address must be the as it was in the main namespace.
sudo ip netns exec ${NAMESPACE_1} ifconfig ${INTERFACE_1} ${INTERFACE_1_PRIV_IP} up

# SETUP: Bring up the loopback interface (as it may be needed by processes run in new namespace).
sudo ip netns exec ${NAMESPACE_1} ifconfig lo 127.0.0.1/8 up

# CHECKUP: List interfaces (loopback and INTERFACE_1) in the new namespace
sudo ip netns exec ${NAMESPACE_1} ip addr show

# CHECKUP: Verify route table.
sudo ip netns exec ${NAMESPACE_1} route -n

# SETUP: Add default gateway to route in new namespace.
sudo ip netns exec ${NAMESPACE_1} route add default gw 192.168.7.1

# CHECKUP: Verify route table again.
sudo ip netns exec ${NAMESPACE_1} route -n

# DONE: Use new namesapce.
sudo ip netns exec ${NAMESPACE_1} ping 8.8.8.8
sudo ip netns exec ${NAMESPACE_1} traceroute 8.8.8.8

# SETUP: Fix DNS
sudo mkdir -pv /etc/netns/${NAMESPACE_1}
sudo echo "nameserver 8.8.8.8" > /etc/netns/${NAMESPACE_1}/resolv.conf


sudo ip netns exec ${NAMESPACE_1} curl ifconfig.me/ip
sudo ip netns exec ${NAMESPACE_1} curl --silent ifconfig.me/ip

# EXTRA: Undo changes (revert to the original state of IP settings)
sudo ip netns del ${NAMESPACE_1}

引用自：https://serverfault.com/questions/1088813