MicP a écrit
…Le seul "truc" (qui m'étonne) est le cron pour "réveiller" la connexion…
Si ma machine ne fait plus aucune requête vers le web pendant plus de 130 secondes, je perds mon accès puisque je dépasse la limite.
Dès qu'une requête est faite, .........

Il me semble que NetworkManager fait maintenant cette tache de "fond".

Feb 15 11:02:15 L NetworkManager[662]: <info>  [1518688935.3891]   lease time 130
Feb 15 11:02:15 L NetworkManager[662]: <info>  [1518688935.3893]   nameserver '212.27.40.241'
Feb 15 11:02:15 L NetworkManager[662]: <info>  [1518688935.3893]   nameserver '212.27.40.240'
Feb 15 11:02:15 L NetworkManager[662]: <info>  [1518688935.3894] dhcp4 (wlp0s9): state changed bound -> bound
Feb 15 11:02:15 L dbus[613]: [system] Activating via systemd: service name='org.freedesktop.nm_dispatcher' unit='dbus-org.freedesktop.nm-dispatcher.service'
Feb 15 11:02:15 L systemd[1]: Starting Network Manager Script Dispatcher Service...
Feb 15 11:02:15 L dbus[613]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
Feb 15 11:02:15 L nm-dispatcher: req:1 'dhcp4-change' [wlp0s9]: new request (1 scripts)
Feb 15 11:02:15 L systemd[1]: Started Network Manager Script Dispatcher Service.
Feb 15 11:02:15 L nm-dispatcher: req:1 'dhcp4-change' [wlp0s9]: start running ordered scripts...
Feb 15 11:02:15 L dhclient[812]: bound to 10.57.194.183 -- renewal in 58 seconds.
Feb 15 11:03:13 L dhclient[812]: DHCPREQUEST of 10.57.194.183 on wlp0s9 to 10.63.255.254 port 67 (xid=0x37498c30)
Feb 15 11:03:13 L dhclient[812]: DHCPACK of 10.57.194.183 from 10.63.255.254
Feb 15 11:03:13 L NetworkManager[662]: <info>  [1518688993.7767]   address 10.57.194.183
Feb 15 11:03:13 L NetworkManager[662]: <info>  [1518688993.7779]   plen 13 (255.248.0.0)
Feb 15 11:03:13 L NetworkManager[662]: <info>  [1518688993.7789]   gateway 10.63.255.254
Feb 15 11:03:13 L NetworkManager[662]: <info>  [1518688993.7798]   server identifier 10.63.255.254
Feb 15 11:03:13 L NetworkManager[662]: <info>  [1518688993.7808]   lease time 130
Feb 15 11:03:13 L NetworkManager[662]: <info>  [1518688993.7817]   nameserver '212.27.40.241'
Feb 15 11:03:13 L NetworkManager[662]: <info>  [1518688993.7818]   nameserver '212.27.40.240'
Feb 15 11:03:13 L NetworkManager[662]: <info>  [1518688993.7819] dhcp4 (wlp0s9): state changed bound -> bound
Feb 15 11:03:13 L dbus[613]: [system] Activating via systemd: service name='org.freedesktop.nm_dispatcher' unit='dbus-org.freedesktop.nm-dispatcher.service'
Feb 15 11:03:13 L systemd[1]: Starting Network Manager Script Dispatcher Service...
Feb 15 11:03:13 L dbus[613]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
Feb 15 11:03:13 L systemd[1]: Started Network Manager Script Dispatcher Service.
Feb 15 11:03:13 L dhclient[812]: bound to 10.57.194.183 -- renewal in 56 seconds.
Feb 15 11:03:13 L nm-dispatcher: req:1 'dhcp4-change' [wlp0s9]: new request (1 scripts)
Feb 15 11:03:13 L nm-dispatcher: req:1 'dhcp4-change' [wlp0s9]: start running ordered scripts...
Feb 15 11:04:09 L dhclient[812]: DHCPREQUEST of 10.57.194.183 on wlp0s9 to 10.63.255.254 port 67 (xid=0x37498c30)
Feb 15 11:04:09 L dhclient[812]: DHCPACK of 10.57.194.183 from 10.63.255.254
Feb 15 11:04:09 L NetworkManager[662]: <info>  [1518689049.4654]   address 10.57.194.183
Feb 15 11:04:09 L NetworkManager[662]: <info>  [1518689049.4665]   plen 13 (255.248.0.0)
Feb 15 11:04:09 L NetworkManager[662]: <info>  [1518689049.4676]   gateway 10.63.255.254
Feb 15 11:04:09 L NetworkManager[662]: <info>  [1518689049.4687]   server identifier 10.63.255.254
Feb 15 11:04:09 L NetworkManager[662]: <info>  [1518689049.4697]   lease time 130

lu16043@L:/var/log$ cat syslog | grep identifier | cut -c 68-98|sort -k3|uniq -c
    252 server identifier 10.63.255.254
lu16043@L:/var/log$