dhcpcd-discuss

Hi Roy,

Den 21.04.2020 20:54, skrev Roy Marples:
> On 21/04/2020 16:14, Tor Rune Skoglund wrote:
> > there is a --dhcp option to dhcpcd which seems to be needed when 
> > using raw-ip with qmi modems. I have systems who are being moved from 
> > 802-3 to raw-ip, since newer modems seem to lack support for 802-3. 
> > To keep the setup as generic as possible, we still would like to use 
> > dhcpcd without having to define too many details about the actual 
> > type of modem on beforehand. Hence, for gms modems using qmi and 
> > raw-ip, ideally we would like to just run dhcpcd in the background 
> > and it should "just work" when the modem connects, much as when using 
> > 802-3 (except for a -HUP to dhcpcd).
> >
> > The *only* way I am able to get dhcpcd to work is by running "dhcpcd 
> > --dhcp -z wwp*". That always works.
> >
> > However, it never works if dhcpcd is already running in the 
> > background, no matter if it was started with --dhcp or not, and no 
> > matter if the config file's allowinterfaces includes ww*.
> >
> > So my questions are:
> >
> > - What does --dhcp actually do in this case? man dhcpcd (at least on 
> > my system) does not document the --dhcp option.
>
> dhcpcd.conf(5) does :)

Ah! :)

> > - What am I doing wrong...? Kindof out of clues now. :)
> >
> > ip a on wwan, before after the ip address is set:
> >
> > 5: wwp0s20u5u1i8: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 
> > qdisc pfifo_fast state UNKNOWN group default qlen 1000
> >      link/none
> >      inet 10.214.215.169/30 brd 10.214.215.171 scope global dynamic 
> > noprefixroute wwp0s20u5u1i8
> >         valid_lft 6868sec preferred_lft 5968sec
> >
> > These are minimalistic systems using OpenRC and no NetworkManager nor 
> > ModemManager. Kernel is 4.9. dhcpcd is 8.1.7 from Gentoo. udhcpc 
> > works on the same system.
> >
> > I presume this is too little info to be able to pinpoint the issue, 
> > but any hints are appreciated. Thanks!
>
> So by default, dhcpcd won't work on POINTOPOINT interfaces without 
> some kind of config.
> putting this at the top of /etc/dhcpcd.conf might fix it for you:
> allowinterfaces wwp*

I just tried this, and still to no avail. Here's the test case. The 
starting point is a newly booted system with dhcpcd running in the 
background. enp1s0 (cable) has received an ip address, and wwp* not - as 
expected - since the mobile connection is not started yet.

head -n 10 /etc/dhcpcd.conf
# A sample configuration for dhcpcd.
# See dhcpcd.conf(5) for details.

# ww* is disabled from P2P by default. Also, need to add other interfaces as
# they will not be enabled by default when allowinterfaces is present.
allowinterfaces ww* en* wl*

# Trying to enable dhcp for all interfaces globally. Does not seem to 
work? Needs to be set per interface?
dhcp

# Setting it on the interface directly for testing. (Problem for later: 
We do not necessarily know the interface name on beforehand.)
tail -n 4 /etc/dhcpcd.conf

interface wwp0s20u5u1i8
dhcp

# Taking link down to be able to switch to raw-ip
ip link set dev wwp0s20u5u1i8 down

# Switching system to raw-ip
qmicli -d /dev/cdc-wdm0 --set-expected-data-format=raw-ip -p
[/dev/cdc-wdm0] expected data format set to: raw-ip

# Making sure that the card is in raw-ip mode
qmicli -d /dev/cdc-wdm0 --wda-get-data-format -p
[/dev/cdc-wdm0] Successfully got data format
                   QoS flow header: no
               Link layer protocol: 'raw-ip'
  Uplink data aggregation protocol: 'disabled'
Downlink data aggregation protocol: 'disabled'
                     NDP signature: '0'
  Uplink data aggregation max size: '0'
Downlink data aggregation max size: '0'

# Starting the network
qmicli -d /dev/cdc-wdm0 --wds-start-network=ip-type=4 -p 
--client-no-release-cid
[/dev/cdc-wdm0] Network started
        Packet data handle: '1137719400'
[/dev/cdc-wdm0] Client ID not released:
        Service: 'wds'
            CID: '9'

# Checking that it did connect
qmicli -d /dev/cdc-wdm0 --wds-get-current-settings -p
[/dev/cdc-wdm0] Current settings retrieved:
           IP Family: IPv4
        IPv4 address: 10.214.215.169
    IPv4 subnet mask: 255.255.255.252
IPv4 gateway address: 10.214.215.170
    IPv4 primary DNS: 193.213.112.4
  IPv4 secondary DNS: 130.67.15.198
                 MTU: 1430
             Domains: none

# Up'ing the interface again
ip link set dev wwp0s20u5u1i8 up

Messages in syslog when doing that:

Apr 22 09:37:21 platform dhcpcd[2221]: wwp0s20u5u1i8: carrier acquired
Apr 22 09:37:21 platform dhcpcd[2221]: wwp0s20u5u1i8: IAID 9a:60:5f:91
Apr 22 09:37:22 platform dhcpcd[2221]: wwp0s20u5u1i8: soliciting a DHCP 
lease

And that's it. At this point, I would have expected the interface to 
receive the address.

However, when running the same procedure *without* dhcpcd already 
running in the background, and then running:

dhcpcd wwp0s20u5u1i8
DUID 00:01:00:01:1a:82:6f:53:08:00:27:00:9e:58
wwp0s20u5u1i8: IAID 00:00:00:05
wwp0s20u5u1i8: soliciting a DHCP lease
wwp0s20u5u1i8: offered 10.214.215.169 from 10.214.215.170
wwp0s20u5u1i8: leased 10.214.215.169 for 7200 seconds
wwp0s20u5u1i8: adding route to 10.214.215.168/30
wwp0s20u5u1i8: adding default route via 10.214.215.170
forked to background, child pid 6814

works.

Any suggestions what I might be doing wrong? In dhcpcd.conf we have 
xidhwaddr and noipv4ll enabled in addition to Gentoo's defaults.

BR, Tor Rune Skoglund