mirror of https://github.com/hak5/openwrt.git
e4259bed3f
This reverts a change made in Sep 2017 [1] which introduced MSG_DONTROUTE flag to prevent udhcpc from reaching out to servers on a different subnet. That change violates RFC2131 by forcing fully configured clients, who got their configurations through an offer relayed by a DHCP relay, from renewing through a unicast request directly to the DHCP server, resulting in the client resorting to boradcasting lease extension requests instead of unicasting them, further breaking RFC2131. The problem with MSG_DONTROUTE appears when talking to a properly configured DHCP server that rejects non-compliant requests. Such server will reject lease extension attempts sent via broadcast rather than unicast, as is the case with Finnish ISPs Telia and DNA as well as Estonian ISP Starman. Once the lease expires without renewal, udhcpc enters init mode, taking down the interfaces with it, and thus causing interruption on every lease expiry. On some ISPs (such as the ones mentioned above) that can be once every 10-20 minutes. The interruptions appear in the logs as such: ---- udhcpc: sending renew to x.x.x.x udhcpc: send: Network unreachable udhcpc: sending renew to 0.0.0.0 udhcpc: sending renew to 0.0.0.0 ... udhcpc: lease lost, entering init state Interface 'wan' has lost the connection Interface 'wan' is now down Network alias 'eth0' link is down udhcpc: sending select for y.y.y.y udhcpc: lease of y.y.y.y obtained, lease time 1200 Network alias 'eth0' link is up Interface 'wan' is now up ---- During lease extension, a fully configured client should be able to reach out to the server from which it recieved the lease for extension, regardless in which network it is; that's up to the gateway to find. [2] This patch ensures that. [1] http://lists.busybox.net/pipermail/busybox-cvs/2017-September/037402.html [2] https://www.netmanias.com/en/post/techdocs/6000/dhcp-network-protocol/ understanding-dhcp-relay-agents Signed-off-by: Adi Shammout <adi.shammout@outlook.com> Signed-off-by: Hans Dedecker <dedeckeh@gmail.com> [PKG_RELEASE increase] |
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