Re: [systemd-devel] Mobile broadband modems support in systemd-networkd
Mantas' and Ulrich's responses gave me insights to dig more. Neither the mbim-cli nor ModemManager sets the IP address on the interface, and some kind of agent needs to do that. 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. 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 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. [root@url-000db95362a6:~]# ip addr show wwan0 6: wwan0: mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 1000 link/ether 52:95:20:b7:93:0f brd ff:ff:ff:ff:ff:ff inet6 2607:fb90:648f:2648:5095:20ff:feb7:930f/64 scope global mngtmpaddr noprefixroute valid_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 medium default via fe80::68d8:1c67:a27:b968 dev wwan0 proto ra metric 1024 expires 65524sec mtu 1500 pref medium 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. My .network file for the interface looks like this: [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 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? 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
Re: [systemd-devel] How does journald talks to other services?
On Fri, Aug 20, 2021 at 2:11 PM Mantas Mikulėnas wrote: > On Fri, Aug 20, 2021 at 2:10 PM Nishant Nayan > wrote: > >> Regarding the below point : >> c) The service prints to stdout/stderr, but systemd attaches the >> service's stdout/stderr to a pipe which is read by journald (using >> sd_journal_stream_fd(3) from libsystemd). See [Service] StandardOutput= in >> systemd.service(5). >> >> I did not see StandardOutput field in [Service] sections of a service >> file, for example sshd.service, but its logs are visible in journalctl. >> Is it by default piped to journal and we need to explicitly mention it >> (StandardOutput=) only when we want to redirect it somewhere else? >> > > StandardOutput=journal is the default setting. > And, actually, sshd doesn't write its messages to stdout anyway – it uses syslog() via /dev/log; most daemons do. -- Mantas Mikulėnas
Re: [systemd-devel] How does journald talks to other services?
On Fri, Aug 20, 2021 at 2:10 PM Nishant Nayan wrote: > Regarding the below point : > c) The service prints to stdout/stderr, but systemd attaches the service's > stdout/stderr to a pipe which is read by journald (using > sd_journal_stream_fd(3) from libsystemd). See [Service] StandardOutput= in > systemd.service(5). > > I did not see StandardOutput field in [Service] sections of a service > file, for example sshd.service, but its logs are visible in journalctl. > Is it by default piped to journal and we need to explicitly mention it > (StandardOutput=) only when we want to redirect it somewhere else? > StandardOutput=journal is the default setting. -- Mantas Mikulėnas
Re: [systemd-devel] How does journald talks to other services?
Regarding the below point : c) The service prints to stdout/stderr, but systemd attaches the service's stdout/stderr to a pipe which is read by journald (using sd_journal_stream_fd(3) from libsystemd). See [Service] StandardOutput= in systemd.service(5). I did not see StandardOutput field in [Service] sections of a service file, for example sshd.service, but its logs are visible in journalctl. Is it by default piped to journal and we need to explicitly mention it (StandardOutput=) only when we want to redirect it somewhere else? Even in my self made service I did not mention StandardOutput=, but I can see the logs in journalctl. Is there a place where I can see .service file defaults ? Nishant On Fri, 20 Aug 2021 at 15:20, Mantas Mikulėnas wrote: > On Fri, Aug 20, 2021 at 12:31 PM Nishant Nayan < > nayan.nishant2...@gmail.com> wrote: > >> Hi, >> My query is how does systemd-journald talk to other services so that >> it stores their logs/output in journal files, which could be displayed >> using journalctl utlity. >> > > Journald doesn't talk to services, services talk to journald: > > a) The service uses the standard syslog(3) call to send basic messages > through the /dev/log socket, where journald (or a traditional syslogd) is > listening. > > b) The service uses sd_journal_print(3) from libsystemd to send structured > messages through /run/systemd/journal/socket (systemd-journald.socket). > Some frameworks, such as GLib, have their own implementations of this > protocol without needing libsystemd. > > c) The service prints to stdout/stderr, but systemd attaches the service's > stdout/stderr to a pipe which is read by journald (using > sd_journal_stream_fd(3) from libsystemd). See [Service] StandardOutput= in > systemd.service(5). > > d) Journald also reads kernel messages (dmesg) from the /dev/kmsg device. > Programs can actually write to /dev/kmsg to generate dmesg messages and > journald will capture them. > > -- > Mantas Mikulėnas >
Re: [systemd-devel] How does journald talks to other services?
Thanks, I will check them out Nishant On Fri, 20 Aug 2021 at 15:22, Lennart Poettering wrote: > On Fr, 20.08.21 15:01, Nishant Nayan (nayan.nishant2...@gmail.com) wrote: > > > Hi, > > My query is how does systemd-journald talk to other services so that > it > > stores their logs/output in journal files, which could be displayed using > > journalctl utlity. > > I am currently looking into systemd journal code to find this out but > so > > far no luck. > > Any suggestions would be appreciated. > > See docs: > > https://www.freedesktop.org/software/systemd/man/systemd-journald.service > > There's a list at the very beginning of the description there that > lists the 5 different ways how log messages are delivered to journald. > > Lennart > > -- > Lennart Poettering, Berlin >
Re: [systemd-devel] How does journald talks to other services?
On Fr, 20.08.21 15:01, Nishant Nayan (nayan.nishant2...@gmail.com) wrote: > Hi, > My query is how does systemd-journald talk to other services so that it > stores their logs/output in journal files, which could be displayed using > journalctl utlity. > I am currently looking into systemd journal code to find this out but so > far no luck. > Any suggestions would be appreciated. See docs: https://www.freedesktop.org/software/systemd/man/systemd-journald.service There's a list at the very beginning of the description there that lists the 5 different ways how log messages are delivered to journald. Lennart -- Lennart Poettering, Berlin
Re: [systemd-devel] Mobile broadband modems support in systemd-networkd
On Thu, Aug 19, 2021 at 10:46 PM Bruce A. Johnson < bjohn...@blueridgenetworks.com> wrote: > I am trying to integrate an MBIM cellular modem (Sierra Wireless MC7455) > into my project, and while there seem to be plenty of people doing the > same thing, all of the references seem to point to using ModemManager to > set up the connection and NetworkManager to manage the IP config > (address, gateway, and DNS). I'd like to avoid having to add > NetworkManager to my build, since I've been getting along nicely with > systemd-networkd for my Ethernet and Wi-Fi interfaces (using iwd to > manage the Wi-Fi connection). Is there any work afoot to get > systemd-networkd to set up the IP address info in concert with > ModemManager, or do I have to force NetworkManager to play nicely with > systemd-networkd? > Wouldn't e.g. `mbimcli` configure IP on its own? -- Mantas Mikulėnas
Re: [systemd-devel] How does journald talks to other services?
On Fri, Aug 20, 2021 at 12:31 PM Nishant Nayan wrote: > Hi, > My query is how does systemd-journald talk to other services so that > it stores their logs/output in journal files, which could be displayed > using journalctl utlity. > Journald doesn't talk to services, services talk to journald: a) The service uses the standard syslog(3) call to send basic messages through the /dev/log socket, where journald (or a traditional syslogd) is listening. b) The service uses sd_journal_print(3) from libsystemd to send structured messages through /run/systemd/journal/socket (systemd-journald.socket). Some frameworks, such as GLib, have their own implementations of this protocol without needing libsystemd. c) The service prints to stdout/stderr, but systemd attaches the service's stdout/stderr to a pipe which is read by journald (using sd_journal_stream_fd(3) from libsystemd). See [Service] StandardOutput= in systemd.service(5). d) Journald also reads kernel messages (dmesg) from the /dev/kmsg device. Programs can actually write to /dev/kmsg to generate dmesg messages and journald will capture them. -- Mantas Mikulėnas
[systemd-devel] How does journald talks to other services?
Hi, My query is how does systemd-journald talk to other services so that it stores their logs/output in journal files, which could be displayed using journalctl utlity. I am currently looking into systemd journal code to find this out but so far no luck. Any suggestions would be appreciated. Regards Nishant
[systemd-devel] Antw: [EXT] [systemd‑devel] Mobile broadband modems support in systemd‑networkd
>>> "Bruce A. Johnson" schrieb am 19.08.2021 um 21:37 in Nachricht <8926b5b1-6d52-cf73-8936-bb097d874...@blueridgenetworks.com>: > I am trying to integrate an MBIM cellular modem (Sierra Wireless MC7455) > into my project, and while there seem to be plenty of people doing the > same thing, all of the references seem to point to using ModemManager to > set up the connection and NetworkManager to manage the IP config > (address, gateway, and DNS). I'd like to avoid having to add > NetworkManager to my build, since I've been getting along nicely with > systemd-networkd for my Ethernet and Wi-Fi interfaces (using iwd to > manage the Wi-Fi connection). Is there any work afoot to get > systemd-networkd to set up the IP address info in concert with > ModemManager, or do I have to force NetworkManager to play nicely with > systemd-networkd? 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)? Regards, Ulrich > > -- > 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: 296D1CD6F2B84CAB https://keys.openpgp.org/
