Hi Arturs, On 12/8/21 17:40, Arturs Laizans wrote: > Hi list, > > Tl;dr: Is it possible to start hostapd without opening an AP and then > later start AP through ctrl interface? > > We are developing a demon that would control wpa_supplicant and > hostapd. Currently, it is easily possible to start wpa_supplcant that > has no network configuration and later add networks through ctrl > interface. However, it seems that for hostapd it is not possible, or > is it? We would like to eventually start a hostapd service that does > nothing to interface (wlan0) until it gets settings from ctrl > interface. Afterward, also disable AP through ctrl interface. Yes, it's possible to run hostapd without any configuration file. Try this: hostapd -g /var/run/hostapd/global You can then add and remove interfaces via wpa_ctrl. Here are some examples using hostapd_cli, but you can achieve the same thing programmatically with the wpa_ctrl interface. Note that at least with the version I am using (2.9), one has to use the 'raw' hostapd_cli command to add and remove interfaces. When using 'raw', the arguments are case sensitive, so 'ADD' will work but 'add' will fail. ### add the interface uap0 # hostapd_cli raw ADD uap0 /var/run/hostapd nl80211 Selected interface 'global' OK # hostapd_cli -i uap0 status state=UNINITIALIZED phy= freq=0 num_sta_non_erp=0 num_sta_no_short_slot_time=0 num_sta_no_short_preamble=0 olbc=0 num_sta_ht_no_gf=0 num_sta_no_ht=0 num_sta_ht_20_mhz=0 num_sta_ht40_intolerant=0 olbc_ht=0 ht_op_mode=0x0 cac_time_seconds=0 cac_time_left_seconds=N/A channel=0 secondary_channel=0 ieee80211n=0 ieee80211ac=0 ieee80211ax=0 beacon_int=100 dtim_period=2 bss[0]=uap0 bssid[0]=00:00:00:00:00:00 ssid[0]= num_sta[0]=0 ### set up an AP on uap0 # hostapd_cli -i uap0 set ssid test OK # hostapd_cli -i uap0 set channel 1 OK # hostapd_cli -i uap0 set hw_mode b OK # hostapd_cli -i uap0 enable OK # hostapd_cli -i uap0 status state=ENABLED phy=phy0 freq=2412 num_sta_non_erp=0 num_sta_no_short_slot_time=0 num_sta_no_short_preamble=0 olbc=0 num_sta_ht_no_gf=0 num_sta_no_ht=0 num_sta_ht_20_mhz=0 num_sta_ht40_intolerant=0 olbc_ht=0 ht_op_mode=0x0 cac_time_seconds=0 cac_time_left_seconds=N/A channel=1 secondary_channel=0 ieee80211n=0 ieee80211ac=0 ieee80211ax=0 beacon_int=100 dtim_period=2 supported_rates=02 04 0b 16 max_txpower=20 bss[0]=uap0 bssid[0]=00:09:a7:xx:xx:xx ssid[0]=test num_sta[0]=0 ### temporarily disable AP on uap0 # hostapd_cli -i uap0 disable OK # hostapd_cli -i uap0 status state=DISABLED phy=phy0 freq=2412 num_sta_non_erp=0 num_sta_no_short_slot_time=0 num_sta_no_short_preamble=0 olbc=0 num_sta_ht_no_gf=0 num_sta_no_ht=0 num_sta_ht_20_mhz=0 num_sta_ht40_intolerant=0 olbc_ht=0 ht_op_mode=0x0 cac_time_seconds=0 cac_time_left_seconds=N/A channel=1 secondary_channel=0 ieee80211n=0 ieee80211ac=0 ieee80211ax=0 beacon_int=100 dtim_period=2 bss[0]=uap0 bssid[0]=00:09:a7:xx:xx:xx ssid[0]=test num_sta[0]=0 ### remove interface uap0 (note: use -iglobal to access the global wpa_ctrl interface, otherwise hostapd_cli might pick another interface to use and the ADD command will fail) # hostapd_cli raw REMOVE uap0 Selected interface 'uap0' UNKNOWN COMMAND # hostapd_cli -iglobal raw REMOVE uap0 OK # hostapd_cli -i uap0 status Failed to connect to hostapd - wpa_ctrl_open: No such file or directory ### other tips You can disable an interface and then reconfigure it on the fly like above, e.g. to change SSID. Note that this usage of hostapd is not very well documented, so some things may not behave as you expect. You cannot, for example, just do `hostapd_cli -i uap0 channel 6` and expect the AP to switch channel while the AP is enabled. But if you disable/enable it then the channel will change. However, if your driver supports it, you can use the chan_switch command. Another tip is to use the configuration 'ssid2' rather than 'ssid' if you want to be confident that your SSID is exactly as you intended, since the wpa_ctrl interface parsing can screw it up sometimes. 'ssid2' takes a hex-formatted argument like '616263' for an SSID 'ABC'. Hope that helps! Kind regards, Alvin _______________________________________________ Hostap mailing list Hostap@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/hostap
