拯救中区寝室网络！

又是一篇流水文，全文基本参照 https://iedon.com/2020/11/11/809.html，但是不想把 usb-modeswitch 包删掉，会对其他应用有影响。不过我不太需要 IPv6，我只要能上网就好了（

购入了一块 me909s 后在电脑上工作良好，不过我想放 OpenWRT 上开热点。

和官方教程「失去同步」

装好基础的包之后（参照官方教程：https://openwrt.org/docs/guide-user/network/wan/wwan/ethernetoverusb_ncm），我出现了五个 USB 串口，但是一直没有 /dev/cdc-wdm0，在 Troubleshooting 也没找到对应的解决办法（当然我最后成功使用的时候也没看到这个设备）：

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$ l /dev
...
crw-rw----    1 root     dialout   188,   0 Oct 11 16:46 ttyUSB0
crw-rw----    1 root     dialout   188,   1 Oct 11 16:46 ttyUSB1
crw-rw----    1 root     dialout   188,   2 Oct 11 16:46 ttyUSB2
crw-rw----    1 root     dialout   188,   3 Oct 11 16:46 ttyUSB3
crw-rw----    1 root     dialout   188,   4 Oct 11 16:46 ttyUSB4
...

lsusb 能看到设备：

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$ lsusb
Bus 001 Device 004: ID 0424:7800
Bus 001 Device 006: ID 12d1:15c1 Huawei Technologies Co., Ltd. HUAWEI Mobile V7R11
Bus 001 Device 003: ID 0424:2514
Bus 001 Device 002: ID 0424:2514
Bus 001 Device 001: ID 1d6b:0002 Linux 5.4.143 dwc_otg_hcd DWC OTG Controller

既然把 usb-modeswitch 包删掉可以解决，那是不是改下 usbmode 识别就好了？

改 usbmode

参照 https://forum.openwrt.org/t/me909s-120-problem-with-usb-modeswitch-and-huawei-cdc-ncm/38639，把 /etc/usb-mode.json 按以下 patch 修改：

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                "12d1:15c1": {
                        "*": {
<                               "msg": [  ],
<                               "config": 0
---
>                               "mode": "Huawei",
>                               "msg": [  ]
                        }
                },

从 dmesg 里可以看到，之前试图加载 usb_fs，现在是 GSM modem：

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$ dmesg
[  281.012775] cdc_ether 1-1.1.3:2.0 wwan0: register 'cdc_ether' at usb-3f980000.usb-1.1.3, Mobile Broadband Network Device, **:**:**:**:00:00
[  281.028942] option 1-1.1.3:2.2: GSM modem (1-port) converter detected
[  281.037278] usb 1-1.1.3: GSM modem (1-port) converter now attached to ttyUSB0
[  281.046865] option 1-1.1.3:2.3: GSM modem (1-port) converter detected
[  281.055155] usb 1-1.1.3: GSM modem (1-port) converter now attached to ttyUSB1
[  281.064489] option 1-1.1.3:2.4: GSM modem (1-port) converter detected
[  281.072621] usb 1-1.1.3: GSM modem (1-port) converter now attached to ttyUSB2
[  281.081761] option 1-1.1.3:2.5: GSM modem (1-port) converter detected
[  281.089952] usb 1-1.1.3: GSM modem (1-port) converter now attached to ttyUSB3
[  281.099293] option 1-1.1.3:2.6: GSM modem (1-port) converter detected
[  281.107380] usb 1-1.1.3: GSM modem (1-port) converter now attached to ttyUSB4
[  281.146071] cdc_ether 1-1.1.3:2.0 wwan0: unregister 'cdc_ether' usb-3f980000.usb-1.1.3, Mobile Broadband Network Device
[  281.279324] usb 1-1.1.3: usbfs: process 12612 (usbmode) did not claim interface 1 before use
[  281.492212] usb 1-1.1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0
[  281.553347] usb 1-1.1.3: usbfs: process 12936 (usbmode) did not claim interface 1 before use
[  281.766858] usb 1-1.1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0
[  281.835814] usb 1-1.1.3: usbfs: process 13103 (usbmode) did not claim interface 1 before use
[  282.048076] usb 1-1.1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0
[  282.126266] usb 1-1.1.3: usbfs: process 13270 (usbmode) did not claim interface 1 before use
[  282.338888] usb 1-1.1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0
[  282.406846] usb 1-1.1.3: usbfs: process 13438 (usbmode) did not claim interface 1 before use
[  282.620191] usb 1-1.1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0
[  282.699833] usb 1-1.1.3: usbfs: process 13605 (usbmode) did not claim interface 1 before use
[  282.912531] usb 1-1.1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0
[  282.981760] usb 1-1.1.3: usbfs: process 13772 (usbmode) did not claim interface 1 before use
[  283.193891] usb 1-1.1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0
[  835.765729] usb 1-1.1.3: usbfs: process 20913 (usbmode) did not claim interface 1 before use
[  835.978790] usb 1-1.1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0
[  873.162684] usb 1-1.1.3: usbfs: process 21391 (usbmode) did not claim interface 1 before use
[  873.375786] usb 1-1.1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0
[ 1401.420537] usb 1-1.1.3: usbfs: process 27594 (usbmode) did not claim interface 1 before use
[ 1401.633710] usb 1-1.1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0
[ 1763.028676] usb 1-1.1.3: USB disconnect, device number 5
[ 1763.038490] option1 ttyUSB0: GSM modem (1-port) converter now disconnected from ttyUSB0
[ 1763.053528] option 1-1.1.3:2.2: device disconnected
[ 1763.061609] option1 ttyUSB1: GSM modem (1-port) converter now disconnected from ttyUSB1
[ 1763.073199] option 1-1.1.3:2.3: device disconnected
[ 1763.080179] option1 ttyUSB2: GSM modem (1-port) converter now disconnected from ttyUSB2
[ 1763.091212] option 1-1.1.3:2.4: device disconnected
[ 1763.097960] option1 ttyUSB3: GSM modem (1-port) converter now disconnected from ttyUSB3
[ 1763.109018] option 1-1.1.3:2.5: device disconnected
[ 1763.115648] option1 ttyUSB4: GSM modem (1-port) converter now disconnected from ttyUSB4
[ 1763.126611] option 1-1.1.3:2.6: device disconnected
[ 1771.769050] usb 1-1.1.3: new high-speed USB device number 6 using dwc_otg
[ 1771.910715] usb 1-1.1.3: New USB device found, idVendor=12d1, idProduct=15c1, bcdDevice= 1.02
[ 1771.925254] usb 1-1.1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 1771.936957] usb 1-1.1.3: Product: HUAWEI Mobile V7R11
[ 1771.943591] usb 1-1.1.3: Manufacturer: Huawei Technologies Co., Ltd.
[ 1771.951524] usb 1-1.1.3: SerialNumber: 0123456789ABCDEF
[ 1771.962003] cdc_ether 1-1.1.3:2.0 wwan0: register 'cdc_ether' at usb-3f980000.usb-1.1.3, Mobile Broadband Network Device, **:**:**:**:00:00
[ 1771.978389] option 1-1.1.3:2.2: GSM modem (1-port) converter detected
[ 1771.986666] usb 1-1.1.3: GSM modem (1-port) converter now attached to ttyUSB0
[ 1771.996179] option 1-1.1.3:2.3: GSM modem (1-port) converter detected
[ 1772.004302] usb 1-1.1.3: GSM modem (1-port) converter now attached to ttyUSB1
[ 1772.013839] option 1-1.1.3:2.4: GSM modem (1-port) converter detected
[ 1772.022058] usb 1-1.1.3: GSM modem (1-port) converter now attached to ttyUSB2
[ 1772.031549] option 1-1.1.3:2.5: GSM modem (1-port) converter detected
[ 1772.039785] usb 1-1.1.3: GSM modem (1-port) converter now attached to ttyUSB3
[ 1772.049279] option 1-1.1.3:2.6: GSM modem (1-port) converter detected
[ 1772.057528] usb 1-1.1.3: GSM modem (1-port) converter now attached to ttyUSB4

ip l 看到了 wwan0 网卡：

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$ ip l
...
9: br-lan: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether **:**:**:**:df:4d brd ff:ff:ff:ff:ff:ff
16: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
    link/ether **:**:**:**:7b:29 brd ff:ff:ff:ff:ff:ff
18: wwan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether **:**:**:**:00:00 brd ff:ff:ff:ff:ff:ff

用 AT 去拨号失败：

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$ echo "AT\$QCRMCALL=1,1" > /dev/ttyUSB2

$ udhcpc -i wwan0
udhcpc: started, v1.33.1
udhcpc: sending discover
udhcpc: sendto: Network is down
udhcpc: read error: Network is down, reopening socket
udhcpc: sending discover
udhcpc: sendto: Network is down
udhcpc: read error: Network is down, reopening socket
udhcpc: sending discover
udhcpc: sendto: Network is down
udhcpc: read error: Network is down, reopening socket
udhcpc: read error: Network is down, reopening socket
udhcpc: read error: Network is down, reopening socket
udhcpc: read error: Network is down, reopening socket
udhcpc: read error: Network is down, reopening socket
udhcpc: read error: Network is down, reopening socket
udhcpc: read error: Network is down, reopening socket
udhcpc: read error: Network is down, reopening socket
udhcpc: sendto: Network is down
udhcpc: read error: Network is down, reopening socket
udhcpc: sendto: Network is down
udhcpc: read error: Network is down, reopening socket
^C

但是还是没有 cdc-wdm0 设备：

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$ l /dev/cdc-wdm0
ls: /dev/cdc-wdm0: No such file or directory

上网

把 /etc/config/network 加上 ncm，设备也直接用的 ttyUSB0（这一步也可以在 luci 里加，但是我懒得放图了）：

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config interface 'wwan'
        option proto 'ncm'
        option device '/dev/ttyUSB0'
        option mode 'auto'
        option apn 'ctnet'
        option ipv6 'auto'

对 wwan0 dhcp，成功！

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$ udhcpc -i wwan0
udhcpc: started, v1.33.1
udhcpc: sending discover
udhcpc: sending select for 100.118.151.172
udhcpc: lease of 100.118.151.172 obtained, lease time 518400
udhcpc: ip addr add 100.118.151.172/255.255.255.248 broadcast + dev wwan0
udhcpc: setting default routers: 100.118.151.169

能在中区上网了（