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Minecraft 如何寻找 LAN 服务器？

tag-icon • tag-icon switch minecraft upnp
Minecraft 如何寻找 LAN 服务器？

Minecraft 客户端（当您进入“多人游戏”模式时）显示“正在扫描 LAN 以查找本地服务器...”

它在做什么？

这是我的问题：如果计算机 A 和计算机 B 通过 Switch1 连接在一起，那么计算机 A 可以运行 minecraft 客户端并在计算机 B 上找到 minecraft 服务器。 但如果计算机C通过Switch2连接，C看不到B上运行的服务器。但是，C可以ping通B，并且如果直接输入此IP和端口，C可以连接到10.1.10.143:64134的服务器。

因此，客户端定位服务器的机制以某种方式被 Switch2 阻止。这是 UPnP 吗？还是类似的东西？

它是巨大的痛苦每次启动 minecraft 服务器时跟踪变化的 IP 地址和变化的端口号。

答案1

我在 Wireshark 上进行了一些数据包捕获，据我所知，它使用 IGMPv2 数据包发送到较少使用的多播地址 (224.0.2.60)，要求运行 Minecraft 服务器的任何人报告。它使用“成员报告”来执行此操作。

对于技术爱好者来说，这里是完整的数据包转储信息：

Frame 10: 46 bytes on wire (368 bits), 46 bytes captured (368 bits) on interface 0
    Interface id: 0 (\Device\NPF_{F0A28F43-6094-447F-A150-434AFC4BB19B})
    Encapsulation type: Ethernet (1)
    Arrival Time: Aug 25, 2016 22:25:55.171363000 US Mountain Standard Time
    [Time shift for this packet: 0.000000000 seconds]
    Epoch Time: 1472189155.171363000 seconds
    [Time delta from previous captured frame: 0.235431000 seconds]
    [Time delta from previous displayed frame: 0.235431000 seconds]
    [Time since reference or first frame: 1.234950000 seconds]
    Frame Number: 10
    Frame Length: 46 bytes (368 bits)
    Capture Length: 46 bytes (368 bits)
    [Frame is marked: False]
    [Frame is ignored: False]
    [Protocols in frame: eth:ethertype:ip:igmp:igmp]
    [Coloring Rule Name: Routing]
    [Coloring Rule String: hsrp || eigrp || ospf || bgp || cdp || vrrp || carp || gvrp || igmp || ismp]
Ethernet II, Src: Giga-Byt_91:9c:dc (fc:aa:14:91:9c:dc), Dst: IPv4mcast_02:3c (01:00:5e:00:02:3c)
    Destination: IPv4mcast_02:3c (01:00:5e:00:02:3c)
        Address: IPv4mcast_02:3c (01:00:5e:00:02:3c)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
    Source: Giga-Byt_91:9c:dc (fc:aa:14:91:9c:dc)
        Address: Giga-Byt_91:9c:dc (fc:aa:14:91:9c:dc)
        .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
        .... ...0 .... .... .... .... = IG bit: Individual address (unicast)
    Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 192.168.1.46, Dst: 224.0.2.60
    0100 .... = Version: 4
    .... 0110 = Header Length: 24 bytes
    Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
    Total Length: 32
    Identification: 0x4347 (17223)
    Flags: 0x00
        0... .... = Reserved bit: Not set
        .0.. .... = Don't fragment: Not set
        ..0. .... = More fragments: Not set
    Fragment offset: 0
    Time to live: 1
    Protocol: IGMP (2)
    Header checksum: 0x0000 [validation disabled]
        [Good: False]
        [Bad: False]
    Source: 192.168.1.46
    Destination: 224.0.2.60
    [Source GeoIP: Unknown]
    [Destination GeoIP: Unknown]
    Options: (4 bytes), Router Alert
        Router Alert (4 bytes): Router shall examine packet (0)
            Type: 148
                1... .... = Copy on fragmentation: Yes
                .00. .... = Class: Control (0)
                ...1 0100 = Number: Router Alert (20)
            Length: 4
            Router Alert: Router shall examine packet (0)
Internet Group Management Protocol
    [IGMP Version: 2]
    Type: Membership Report (0x16)
    Max Resp Time: 0.0 sec (0x00)
    Header checksum: 0x07c3 [correct]
    Multicast Address: 224.0.2.60

以下是原始数据包转储：

0000   01 00 5e 00 02 3c fc aa 14 91 9c dc 08 00 46 00  ..^..<........F.
0010   00 20 43 47 00 00 01 02 00 00 c0 a8 01 2e e0 00  . CG............
0020   02 3c 94 04 00 00 16 00 07 c3 e0 00 02 3c        .<...........<

因此，要回答您的问题，您可能在路由器上关闭了多播，或者禁用了 IGMP。我不太熟悉这些标志，但看起来选项/路由器警报字段中可能有一些内容……可能告诉路由器不要将多播转发到子网之外，但这只是猜测。

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