When I start the connection using ModemManager, I am able to retrieve addresses that mmcli displays like the below. If I manually assign the IPv4 address to the interface and set up the route, I'm able to send traffic to and from other nodes. I haven't yet looked into how ModemManager communicates this info to NetworkManager or how things like a change of address are handled. As I see it, these addresses aren't really static, because the IPv6 addresses are different from one mobile session to the next.
I took a closer look at what's going on with systemd-networkd, and I found whether I use ModemManager or mbim-cli to connect to the mobile network, the .network file will be processed, but _only after I restart systemd-networkd_. When it is processed, the only address the interface gets is an IPv6 address, and it doesn't match the one in the ModemManager message above. I'm guessing that T-Mobile isn't providing DHCP for IPv4, and probably with good reason.-------------------------------- IPv4 configuration | method: static | address: 6.147.139.XXX | prefix: 30 | gateway: 6.147.139.YYY | dns: 10.177.0.34, 10.177.0.210 | mtu: 1500 -------------------------------- IPv6 configuration | method: static | address: 2607:fb90:648f:2648:a5b3:8146:95aa:2955 | prefix: 64 | gateway: 2607:fb90:648f:2648:68d8:1c67:a27:b968 | dns: fd00:976a::9, fd00:976a::10 | mtu: 1500 --------------------------------
At this point, I have a usable IP(v6) connection managed by systemd-networkd, but I can't see any indication that I'm getting DNS information. This could be that the only DNS tools I know of on my box are nslookup from Busybox and the gethostbyname() call in Python. Both are returning ESRCH.[root@url-000db95362a6:~]# ip addr show wwan06: wwan0: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 1000link/ether 52:95:20:b7:93:0f brd ff:ff:ff:ff:ff:ffinet6 2607:fb90:648f:2648:5095:20ff:feb7:930f/64 scope global mngtmpaddr noprefixroutevalid_lft forever preferred_lft forever inet6 fe80::5095:20ff:feb7:930f/64 scope link valid_lft forever preferred_lft forever [root@url-000db95362a6:~]# ip -6 route ::1 dev lo proto kernel metric 256 pref medium 2607:fb90:648f:2648::/64 dev wwan0 proto ra metric 1024 pref medium fe80::/64 dev wwan0 proto kernel metric 256 pref medium ff00::/8 dev wwan0 metric 256 pref mediumdefault via fe80::68d8:1c67:a27:b968 dev wwan0 proto ra metric 1024 expires 65524sec mtu 1500 pref medium
My .network file for the interface looks like this:
Is there something more that I need to add to get DNS addresses via the IPv6 router solicitation/advertisement mechanism, or does it appear that T-Mobile isn't providing DNS addresses except via the klunky method exposed by ModemManager?[Match] Name=wwan0 [Network] Description=WAN connection on wwan0 DHCP=yes IPv6AcceptRA=true [DHCP] UseDNS=yes UseNTP=no SendHostname=no RouteMetric=0 [IPv6AcceptRA] UseDNS=true
Bruce A. Johnson | Firmware Engineer Blue Ridge Networks, Inc. 14120 Parke Long Court Suite 103 | Chantilly, VA 20151 Main: 1.800.722.1168 | Direct: 703-633-7332 http://www.blueridgenetworks.com OpenPGP key ID: 296D1CD6F2B84CABhttps://keys.openpgp.org/ On 20/08/2021 03:15, Ulrich Windl wrote:
Isn't the trick that the WIFI driver or kernel doe most of the magic required to make WIFI work, while a modem driver typically does not know much about the modem, i.e. a cellular modem requires some "special treatment".Dumb question: Does it work without systemd (i.e..: Do yoiu hgave some code that does all that handling)?
On 20/08/2021 05:51, Mantas Mikulėnas wrote:
Wouldn't e.g. `mbimcli` configure IP on its own?
OpenPGP_signature
Description: OpenPGP digital signature
