☰

net.ipv6.conf.all.forwarding=1 是否相当于为所有单独的接口启用转发？

tag-icon • tag-icon linux networking routing ipv6 forwarding
net.ipv6.conf.all.forwarding=1 是否相当于为所有单独的接口启用转发？

或者这是启用 IPv6 转发的唯一方法？

/proc/sys/net/ipv6/conf# grep '' */forwarding
all/forwarding:0
default/forwarding:1
eth0/forwarding:1
lo/forwarding:1
nat64/forwarding:1
tunl0/forwarding:1
veth_cm/forwarding:1
wifi0/forwarding:1
wlan0/forwarding:1

不路由。我在 Wireshark 中看到数据包，但它们未到达 ip6table。

/proc/sys/net/ipv6/conf# grep '' */forwarding
all/forwarding:1
default/forwarding:1
eth0/forwarding:1
lo/forwarding:1
nat64/forwarding:1
tunl0/forwarding:1
veth_cm/forwarding:1
wifi0/forwarding:1
wlan0/forwarding:1

现在网络开始工作。

/proc/sys/net/ipv6/conf# grep '' */forwarding
all/forwarding:1
default/forwarding:0
eth0/forwarding:0
lo/forwarding:0
nat64/forwarding:0
tunl0/forwarding:0
veth_cm/forwarding:0
wifi0/forwarding:0
wlan0/forwarding:0

网络仍然有效。是否使用了那些单独的每个接口交换机？难道是 Linux 内核 bug（现在运行版本 4.9.5）。

答案1

看起来确实它的设计工作方式与 IPv4*/forwarding和不同all/forwarding：

从https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt：

conf/all/forwarding - BOOLEAN
    Enable global IPv6 forwarding between all interfaces.

    IPv4 and IPv6 work differently here; e.g. netfilter must be used
    to control which interfaces may forward packets and which not.

    This also sets all interfaces' Host/Router setting
    'forwarding' to the specified value.  See below for details.

    This referred to as global forwarding.

forwarding - INTEGER
    Configure interface-specific Host/Router behaviour.

    Note: It is recommended to have the same setting on all
    interfaces; mixed router/host scenarios are rather uncommon.

    Possible values are:
        0 Forwarding disabled
        1 Forwarding enabled

    FALSE (0):

    By default, Host behaviour is assumed.  This means:

    1. IsRouter flag is not set in Neighbour Advertisements.
    2. If accept_ra is TRUE (default), transmit Router
       Solicitations.
    3. If accept_ra is TRUE (default), accept Router
       Advertisements (and do autoconfiguration).
    4. If accept_redirects is TRUE (default), accept Redirects.

    TRUE (1):

    If local forwarding is enabled, Router behaviour is assumed.
    This means exactly the reverse from the above:

    1. IsRouter flag is set in Neighbour Advertisements.
    2. Router Solicitations are not sent unless accept_ra is 2.
    3. Router Advertisements are ignored unless accept_ra is 2.
    4. Redirects are ignored.

    Default: 0 (disabled) if global forwarding is disabled (default),
         otherwise 1 (enabled).

因此，每个接口forwarding仅用于辅助功能，例如各种标志和特殊数据包行为，而不是用于决定是否重新传输数据包。

相关内容