我有一台 Raspberry Pi，运行最新的 Raspberry Pi 操作系统和 Linux 内核 6.6。
我有一台 Quectel EC25 调制解调器，带有一个活动 SIM 卡，可以成功连接到互联网。我可以通过这个 wwan0 接口 ping 8.8.8.8，但不能 ping google.com。我尝试在 resolv.conf 中设置名称服务器条目，但 DNS 似乎一直失败。我已禁用 NetworkManager 和 systemd-resolved 服务，以便它们不进行交互（运行时它们并没有改善 DNS 情况）。我尝试在网络命名空间内使用 wwan0 接口进行 nslookup 和 dig，它们立即成功。我不明白 dig/nslookup 如何工作，但不明白 ping。如何让 DNS 通过蜂窝调制解调器工作？
网络命名空间设置脚本：
root@raspberrypi:/home/pi/Desktop# cat create_and_enter_ns.sh
#!/bin/bash
MODEM_IF="wwan0"
ip netns add cellular
ip link set $MODEM_IF netns cellular
ip netns exec cellular bash
连接脚本从网络命名空间内部运行：
root@raspberrypi:/home/pi/Desktop# cat connect-cellular.sh
#!/bin/bash
MODEM_IF="wwan0"
echo "-------------------------------------------------------"
echo "*** Setting up cellular modem ..."
ip link set $MODEM_IF down
echo 'Y' | sudo tee /sys/class/net/wwan0/qmi/raw_ip
ip link set $MODEM_IF up
qmicli -p -d /dev/cdc-wdm0 --device-open-net='net-raw-ip|net-no-qos-header' --wds-start-network="apn='super',ip-type=4" --client-no-release-cid
echo "-------------------------------------------------------"
echo "*** Requesting IP Address for modem ..."
udhcpc -q -f -i wwan0
echo "-------------------------------------------------------"
echo "*** Displaying cellular connection details ..."
qmicli -d /dev/cdc-wdm0 --wds-get-current-settings
echo "-------------------------------------------------------"
echo "*** Setting nameservers in resolv.conf ..."
echo "nameserver 8.8.8.8" > /etc/resolv.conf
echo "nameserver 8.8.4.4" > /etc/resolv.conf
echo "-------------------------------------------------------"
echo "*** Displaying routes ..."
ip route
route
echo "-------------------------------------------------------"
echo "*** DNS Lookups ..."
nslookup google.com
dig google.com
echo "-------------------------------------------------------"
echo "*** Attempting pings ..."
echo "*** Pinging 8.8.8.8 ..."
ping -c 3 -W 3 8.8.8.8
echo "*** Pinging google.com ..."
ping -c 3 -W 3 google.com
echo "-------------------------------------------------------"
echo "*** Done ..."
连接脚本输出：
root@raspberrypi:/home/pi/Desktop# ./connect-cellular.sh
-------------------------------------------------------
*** Setting up cellular modem ...
Y
[/dev/cdc-wdm0] Network started
Packet data handle: '2269105392'
[/dev/cdc-wdm0] Client ID not released:
Service: 'wds'
CID: '18'
-------------------------------------------------------
*** Requesting IP Address for modem ...
udhcpc: started, v1.35.0
Dropped protocol specifier '.udhcpc' from 'wwan0.udhcpc'. Using 'wwan0' (ifindex=3).
Failed to revert interface configuration: Unit dbus-org.freedesktop.resolve1.service not found.
udhcpc: broadcasting discover
udhcpc: broadcasting select for 100.75.157.67, server 100.75.157.68
udhcpc: lease of 100.75.157.67 obtained from 100.75.157.68, lease time 7200
Dropped protocol specifier '.udhcpc' from 'wwan0.udhcpc'. Using 'wwan0' (ifindex=3).
Failed to set DNS configuration: Unit dbus-org.freedesktop.resolve1.service not found.
-------------------------------------------------------
*** Displaying cellular connection details ...
[/dev/cdc-wdm0] Current settings retrieved:
IP Family: IPv4
IPv4 address: 100.75.157.67
IPv4 subnet mask: 255.255.255.248
IPv4 gateway address: 100.75.157.68
IPv4 primary DNS: 8.8.4.4
IPv4 secondary DNS: 8.8.8.8
MTU: 1360
Domains: none
-------------------------------------------------------
*** Setting nameservers in resolv.conf ...
-------------------------------------------------------
*** Displaying routes ...
default via 100.75.157.68 dev wwan0
100.75.157.64/29 dev wwan0 proto kernel scope link src 100.75.157.67
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default 100.75.157.68 0.0.0.0 UG 0 0 0 wwan0
100.75.157.64 0.0.0.0 255.255.255.248 U 0 0 0 wwan0
-------------------------------------------------------
*** DNS Lookups ...
Server: 8.8.4.4
Address: 8.8.4.4#53
Non-authoritative answer:
Name: google.com
Address: 142.251.163.139
Name: google.com
Address: 142.251.163.101
Name: google.com
Address: 142.251.163.138
Name: google.com
Address: 142.251.163.102
Name: google.com
Address: 142.251.163.113
Name: google.com
Address: 142.251.163.100
Name: google.com
Address: 2607:f8b0:4004:c1b::8b
Name: google.com
Address: 2607:f8b0:4004:c1b::8a
Name: google.com
Address: 2607:f8b0:4004:c1b::64
Name: google.com
Address: 2607:f8b0:4004:c1b::71
; <<>> DiG 9.18.24-1-Debian <<>> google.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 7473
;; flags: qr rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;google.com. IN A
;; ANSWER SECTION:
google.com. 15 IN A 142.251.163.100
google.com. 15 IN A 142.251.163.101
google.com. 15 IN A 142.251.163.138
google.com. 15 IN A 142.251.163.139
google.com. 15 IN A 142.251.163.102
google.com. 15 IN A 142.251.163.113
;; Query time: 132 msec
;; SERVER: 8.8.4.4#53(8.8.4.4) (UDP)
;; WHEN: Fri Apr 05 02:36:11 BST 2024
;; MSG SIZE rcvd: 135
-------------------------------------------------------
*** Attempting pings ...
*** Pinging 8.8.8.8 ...
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=115 time=145 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=115 time=183 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=115 time=142 ms
--- 8.8.8.8 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 142.221/156.747/183.145/18.697 ms
*** Pinging google.com ...
PING google.com (142.251.163.139) 56(84) bytes of data.
--- google.com ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2056ms
-------------------------------------------------------
*** Done ...
更新：
事实上，DNS 似乎可以正常解析各种域名，但我永远无法通过 wwan0 ping 通它们。
root@raspberrypi:/home/pi/Desktop# dig stackoverflow.com
; <<>> DiG 9.18.24-1-Debian <<>> stackoverflow.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3647
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;stackoverflow.com. IN A
;; ANSWER SECTION:
stackoverflow.com. 300 IN A 104.18.32.7
stackoverflow.com. 300 IN A 172.64.155.249
;; Query time: 168 msec
;; SERVER: 8.8.8.8#53(8.8.8.8) (UDP)
;; WHEN: Fri Apr 05 14:05:58 BST 2024
;; MSG SIZE rcvd: 78
root@raspberrypi:/home/pi/Desktop# ping 104.18.32.7
PING 104.18.32.7 (104.18.32.7) 56(84) bytes of data.
^C
--- 104.18.32.7 ping statistics ---
6 packets transmitted, 0 received, 100% packet loss, time 5098ms
我似乎也无法 ping 1.1.1.1（Cloudflare 公共 DNS）：
root@raspberrypi:/home/pi/Desktop# ping -W 3 -c 1 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=115 time=294 ms
--- 8.8.8.8 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 294.368/294.368/294.368/0.000 ms
root@raspberrypi:/home/pi/Desktop# ping -W 3 -c 1 8.8.4.4
PING 8.8.4.4 (8.8.4.4) 56(84) bytes of data.
64 bytes from 8.8.4.4: icmp_seq=1 ttl=57 time=181 ms
--- 8.8.4.4 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 181.163/181.163/181.163/0.000 ms
root@raspberrypi:/home/pi/Desktop# ping -W 3 -c 1 1.1.1.1
PING 1.1.1.1 (1.1.1.1) 56(84) bytes of data.
--- 1.1.1.1 ping statistics ---
1 packets transmitted, 0 received, 100% packet loss, time 0ms
root@raspberrypi:/home/pi/Desktop#
以下是跟踪路由的结果：
root@raspberrypi:/home/pi/Desktop# traceroute 8.8.8.8
traceroute to 8.8.8.8 (8.8.8.8), 30 hops max, 60 byte packets
1 * * *
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
7 * * *
8 * * dns.google (8.8.8.8) 571.410 ms
root@raspberrypi:/home/pi/Desktop# traceroute google.com
traceroute to google.com (142.251.163.100), 30 hops max, 60 byte packets
1 * * *
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
7 * * *
8 * * *
9 * * *
10 * * *
11 * * *
12 * * *
13 * * *
14 * * *
15 * * *
16 * * *
17 * * *
18 * * *
19 * * *
20 * * *
21 * * *
22 * * *
23 * * *
24 * * *
25 * * *
26 * * *
27 * * *
28 * * *
29 * * *
30 * * *
root@raspberrypi:/home/pi/Desktop# traceroute -n google.com
traceroute to google.com (142.251.163.101), 30 hops max, 60 byte packets
1 * * *
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
7 * * *
8 * * *
9 * * *
10 * * *
11 * * *
12 * * *
13 * * *
14 * * *
15 * * *
16 * * *
17 * * *
18 * * *
19 * * *
20 * * *
21 * * *
22 * * *
23 * * *
24 * * *
25 * * *
26 * * *
27 * * *
28 * * *
29 * * *
30 * * *
root@raspberrypi:/home/pi/Desktop#
更新 2：
我尝试了另一块主板，它带有 PCIe Quectel EC25 调制解调器，可以通过该接口 ping 通谷歌。我仔细检查了那块主板和 Sixfab 主板之间的所有我能想到的东西 - 并没有发现任何错误。但 Sixfab 主板无法 ping 通谷歌（请参阅下面的输出，作为两者之间路由和其他所有内容的比较）。
这可能是与实际 Linux 配置无关的服务级 DNS 问题吗？
其他工作板：
root@iot-gate-imx8plus:~# qmicli -d /dev/cdc-wdm0 --wds-get-current-settings
[/dev/cdc-wdm0] Current settings retrieved:
IP Family: IPv4
IPv4 address: 10.204.79.165
IPv4 subnet mask: 255.255.255.252
IPv4 gateway address: 10.204.79.166
IPv4 primary DNS: 8.8.8.8
IPv4 secondary DNS: 8.8.4.4
MTU: 1500
Domains: none
root@iot-gate-imx8plus:~#
root@iot-gate-imx8plus:~# ifconfig wwan0
wwan0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1500
inet 10.204.79.165 netmask 255.255.255.252 destination 10.204.79.165
unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 1000 (UNSPEC)
RX packets 1538 bytes 197923 (193.2 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 1374 bytes 171063 (167.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
root@iot-gate-imx8plus:~# ip route
default via 10.204.79.166 dev wwan0 metric 10
10.2.0.0/16 dev wg0 scope link
10.204.79.164/30 dev wwan0 proto kernel scope link src 10.204.79.165
root@iot-gate-imx8plus:~#
root@iot-gate-imx8plus:~# ping google.com
PING google.com (142.250.180.14) 56(84) bytes of data.
64 bytes from lhr25s32-in-f14.1e100.net (142.250.180.14): icmp_seq=1 ttl=112 time=236 ms
64 bytes from lhr25s32-in-f14.1e100.net (142.250.180.14): icmp_seq=2 ttl=112 time=275 ms
64 bytes from lhr25s32-in-f14.1e100.net (142.250.180.14): icmp_seq=3 ttl=112 time=243 ms
64 bytes from lhr25s32-in-f14.1e100.net (142.250.180.14): icmp_seq=4 ttl=112 time=274 ms
^C
--- google.com ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3003ms
rtt min/avg/max/mdev = 236.348/257.205/275.411/17.489 ms
root@iot-gate-imx8plus:~# cat /etc/resolv.conf
# This is /run/systemd/resolve/resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known uplink DNS servers. This file lists all configured search domains.
#
# Third party programs should typically not access this file directly, but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
nameserver 8.8.8.8
nameserver 8.8.4.4
search .
Sixfab HAT 失败 DNS：
root@raspberrypi:/home/pi/Desktop# qmicli -d /dev/cdc-wdm0 --wds-get-current-settings
[/dev/cdc-wdm0] Current settings retrieved:
IP Family: IPv4
IPv4 address: 100.75.157.67
IPv4 subnet mask: 255.255.255.248
IPv4 gateway address: 100.75.157.68
IPv4 primary DNS: 8.8.4.4
IPv4 secondary DNS: 8.8.8.8
MTU: 1360
Domains: none
root@raspberrypi:/home/pi/Desktop#
root@raspberrypi:/home/pi/Desktop# ifconfig wwan0
wwan0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1360
inet 100.75.157.67 netmask 255.255.255.248 destination 100.75.157.67
inet6 fe80::b750:b71f:6494:4e58 prefixlen 64 scopeid 0x20<link>
unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 1000 (UNSPEC)
RX packets 153 bytes 16644 (16.2 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 47348 bytes 8168507 (7.7 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
root@raspberrypi:/home/pi/Desktop#
root@raspberrypi:/home/pi/Desktop# ip route
default via 100.75.157.68 dev wwan0 metric 10
100.75.157.64/29 dev wwan0 proto kernel scope link src 100.75.157.67
root@raspberrypi:/home/pi/Desktop#
root@raspberrypi:/home/pi/Desktop# ping -I wwan0 -W 3 -C 3 google.com
PING google.com (142.251.163.100) from 100.75.157.67 wwan0: 56(124) bytes of data.
^C
--- google.com ping statistics ---
19 packets transmitted, 0 received, 100% packet loss, time 18431ms
root@raspberrypi:/home/pi/Desktop#
root@raspberrypi:/home/pi/Desktop# ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=115 time=118 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=115 time=116 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=115 time=115 ms
^C
--- 8.8.8.8 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 115.051/116.219/117.650/1.077 ms
root@raspberrypi:/home/pi/Desktop# cat /etc/resolv.conf
nameserver 8.8.8.8
nameserver 8.8.4.4
search .
root@raspberrypi:/home/pi/Desktop#
更新 3：
我安装了 tshark，然后监控 wwan0，同时尝试在另一个终端中 ping google。有趣的是，接口上收到了 DNS 响应，但 ping 从未得到响应。
root@raspberrypi:/home/pi/Desktop# tshark -i wwan0
Running as user "root" and group "root". This could be dangerous.
Capturing on 'wwan0'
** (tshark:456216) 20:56:56.160995 [Main MESSAGE] -- Capture started.
** (tshark:456216) 20:56:56.161146 [Main MESSAGE] -- File: "/tmp/wireshark_wwan05F4ZL2.pcapng"
1 0.000000000 100.75.157.67 → 8.8.8.8 DNS 56 Standard query 0x4501 A google.com
2 0.000025703 100.75.157.67 → 8.8.8.8 DNS 56 Standard query 0x6c0c AAAA google.com
3 0.287190564 8.8.8.8 → 100.75.157.67 DNS 168 Standard query response 0x6c0c AAAA google.com AAAA 2607:f8b0:4004:c1b::8b AAAA 2607:f8b0:4004:c1b::71 AAAA 2607:f8b0:4004:c1b::66 AAAA 2607:f8b0:4004:c1b::8a
4 0.287191675 8.8.8.8 → 100.75.157.67 DNS 152 Standard query response 0x4501 A google.com A 142.251.163.138 A 142.251.163.102 A 142.251.163.101 A 142.251.163.100 A 142.251.163.113 A 142.251.163.139
5 0.287529002 100.75.157.67 → 142.251.163.138 ICMP 84 Echo (ping) request id=0xb5fb, seq=1/256, ttl=64