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为什么 systemd-networkd 不向 tun 接口添加地址和对等点？

tag-icon • tag-icon systemd-networkd tunneling
为什么 systemd-networkd 不向 tun 接口添加地址和对等点？

我正在尝试创建 tun 接口并通过 systemd-networkd 的 .netdev 和 .network 文件添加地址和对等点。我正在使用 Ubuntu 22.04.3 LTS 和 systemd 249。

我有以下两个配置文件：

/etc/systemd/network/991-tun1.netdev

[NetDev]
Name=tun1
Kind=tun

[Tun]
User=me

/etc/systemd/network/991-tun1.network

[Match]
Name=tun1

[Network]
Address=192.168.3.1/24
IPForward=yes

[Address]
Address=192.168.3.1/24
Peer=192.168.3.2/24

重新启动后，tun1 接口创建正常，但没有地址。

me@host:~$ ip a
...
4: tun1: <NO-CARRIER,POINTOPOINT,MULTICAST,NOARP,UP> mtu 1500 qdisc fq_codel state DOWN group default qlen 500
    link/none

但如果我使用 ifconfig 那么地址会按预期添加。

me@host:~$ sudo ifconfig tun1 192.168.3.1 pointopoint 192.168.3.2 netmask 255.255.255.0
me@host:~$ ip a
...
4: tun1: <NO-CARRIER,POINTOPOINT,MULTICAST,NOARP,UP> mtu 1500 qdisc fq_codel state DOWN group default qlen 500
    link/none 
    inet 192.168.3.1 peer 192.168.3.2/24 scope global tun1
       valid_lft forever preferred_lft forever

重新启动后我可以在日志中看到这一点

me@host:~$ sudo journalctl --unit systemd-networkd -fe|grep tun1
...
systemd-networkd[513]: tun1: loaded tun
systemd-networkd[513]: tun1: Created
systemd-networkd[513]: tun1: netdev has index 4
systemd-networkd[513]: tun1: Permanent MAC address not found for new device, continuing without: Operation not supported
systemd-networkd[513]: tun1: Link 4 added
systemd-networkd[513]: tun1: Saved original MTU 1500 (min: 68, max: 65535)
systemd-networkd[513]: tun1: Flags change: +MULTICAST +POINTOPOINT +NOARP
systemd-networkd[513]: tun1: link pending udev initialization...
systemd-networkd[513]: tun1: udev initialized link
systemd-networkd[513]: tun1: State changed: pending -> initialized
systemd-networkd[513]: tun1: Link state is up-to-date
systemd-networkd[513]: tun1: found matching network '/etc/systemd/network/991-tun1.network'.
systemd-networkd[513]: tun1: State changed: initialized -> configuring
systemd-networkd[513]: Setting '/proc/sys/net/ipv6/conf/tun1/disable_ipv6' to '0'
systemd-networkd[513]: Setting '/proc/sys/net/ipv6/conf/tun1/use_tempaddr' to '0'
systemd-networkd[513]: Setting '/proc/sys/net/ipv6/conf/tun1/accept_ra' to '0'
systemd-networkd[513]: Setting '/proc/sys/net/ipv6/conf/tun1/proxy_ndp' to '0'
systemd-networkd[513]: Setting '/proc/sys/net/ipv4/conf/tun1/promote_secondaries' to '1'
systemd-networkd[513]: tun1: Requested to set IPv6LL address generation mode
systemd-networkd[513]: tun1: Requested to set master interface
systemd-networkd[513]: tun1: Requested to activate link
systemd-networkd[513]: tun1: Requesting address: 192.168.3.1/24 (valid forever, preferred forever), flags: n/a
systemd-networkd[513]: tun1: Requesting address: 192.168.3.1 peer 192.168.3.2/24 (valid forever, preferred forever), flags: n/a
systemd-networkd[513]: tun1: Setting addresses
systemd-networkd[513]: tun1: link_check_ready(): link layer is configuring.
systemd-networkd[513]: tun1: link_check_ready(): link layer is configuring.
systemd-networkd[513]: tun1: link_check_ready(): link layer is configuring.
systemd-networkd[513]: tun1: link_check_ready(): link layer is configuring.
systemd-networkd[513]: tun1: link_check_ready(): link layer is configuring.
systemd-networkd[513]: tun1: link_check_ready(): link layer is configuring.
systemd-networkd[513]: tun1: link_check_ready(): link layer is configuring.
systemd-networkd[513]: tun1: link_check_ready(): link layer is configuring.
systemd-networkd[513]: tun1: Setting IPv6LL address generation mode
systemd-networkd[513]: tun1: Setting master interface
systemd-networkd[513]: tun1: IPv6LL address generation mode set.
systemd-networkd[513]: tun1: master interface set.
systemd-networkd[513]: tun1: link_check_ready(): link is not activated.
systemd-networkd[513]: tun1: Bringing link up
systemd-networkd[513]: tun1: Flags change: +UP
systemd-networkd[513]: tun1: Link UP
systemd-networkd[513]: tun1: link_check_ready(): static addresses are not configured.

为什么 systemd-networkd 没有将地址添加到 tun1 接口以及如何使其添加地址？

答案1

系统网络化（如 NetworkManager）对运营商状态做出反应，这会影响接口上的地址配置。

对于 TUN/TAP 接口，状态将保持在，NO-CARRIER直到用户空间进程（例如ssh -w ...）正确连接到接口：然后虚拟载体状态将切换为已检测到。默认情况下，只有以下部分的配置（例如添加地址）才会由网络化。

要使其忽略运营商状态，应为设备添加以下参数：

[Network]
ConfigureWithoutCarrier=yes
IgnoreCarrierLoss=yes

特别是描述ConfigureWithoutCarrier告诉：

[...] 允许网络配置特定链接，即使它没有运营商。 [...]

第二个参数（在第一个参数启用时可能默认启用，因此这里实际上可能不需要），允许停止并重新启动附加到 TUN 接口（例如ssh -w ...）的用户空间进程，而不会导致设置发生任何更改。

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