Re: GSM: MBIM: How to select authentication type PAP, CHAP etc.

[Aleksander Morgado <aleksander aleksander es>]

Hey

> What I'm missing is a setting like 'gsm.auth-type'.
> Can anyone point me in the right direction?

In NetworkManager you configure what auth types you should NOT use; by
default all these are "no":
ppp.refuse-eap:                         no
ppp.refuse-pap:                         no
ppp.refuse-chap:                        no
ppp.refuse-mschap:                      no
ppp.refuse-mschapv2:                    no

The logic in NM converts those settings to MM allowed-auth bitmask:

        if (nm_setting_ppp_get_noauth(s_ppp))
            allowed_auth = MM_BEARER_ALLOWED_AUTH_NONE;
        if (!nm_setting_ppp_get_refuse_pap(s_ppp))
            allowed_auth |= MM_BEARER_ALLOWED_AUTH_PAP;
        if (!nm_setting_ppp_get_refuse_chap(s_ppp))
            allowed_auth |= MM_BEARER_ALLOWED_AUTH_CHAP;
        if (!nm_setting_ppp_get_refuse_mschap(s_ppp))
            allowed_auth |= MM_BEARER_ALLOWED_AUTH_MSCHAP;
        if (!nm_setting_ppp_get_refuse_mschapv2(s_ppp))
            allowed_auth |= MM_BEARER_ALLOWED_AUTH_MSCHAPV2;
        if (!nm_setting_ppp_get_refuse_eap(s_ppp))
            allowed_auth |= MM_BEARER_ALLOWED_AUTH_EAP;

And ModemManager converts the allowed auth bitmask into one single
value, choosing a "best" default from all the auth settings allowed by
NM:

    if (bearer_auth == MM_BEARER_ALLOWED_AUTH_UNKNOWN) {
        mm_obj_dbg (log_object, "using default (CHAP) authentication method");
        return MBIM_AUTH_PROTOCOL_CHAP;
    }
    if (bearer_auth & MM_BEARER_ALLOWED_AUTH_CHAP)
        return MBIM_AUTH_PROTOCOL_CHAP;
    if (bearer_auth & MM_BEARER_ALLOWED_AUTH_PAP)
        return MBIM_AUTH_PROTOCOL_PAP;
    if (bearer_auth & MM_BEARER_ALLOWED_AUTH_MSCHAPV2)
        return MBIM_AUTH_PROTOCOL_MSCHAPV2;
    if (bearer_auth & MM_BEARER_ALLOWED_AUTH_NONE)
        return MBIM_AUTH_PROTOCOL_NONE;

This logic is not perfect, yes... :/

If you want explicitly PAP, try to set ppp.refuse-chap to "yes" in the
NM settings.

-- 
Aleksander
https://aleksander.es