The client identifier serves as unique identifier just like a unique MAC
address would, so even with identity_leases disabled some DHCP servers
might assign unique leases per identity.
DHCP servers will respond to port 67 if giaddr is non-zero, which we set
if we are not broadcasting. While such messages are received fine via
RAW socket the kernel will respond with an ICMP port unreachable if no
socket is bound to that port. Instead of opening a dummy socket on port
67 just to avoid the ICMPs we can also just operate with a single
socket, bind it to port 67 and send our requests from that port.
Since SO_REUSEADDR behaves on Linux like SO_REUSEPORT does on other
systems we can bind that port even if a DHCP server is running on the
same host as the daemon (this might have to be adapted to make this work
on other systems, but due to the raw socket the plugin is not that portable
anyway).
Since 6a8a44be88b0 the certificate received by the client is verified
first, before checking the cached certificates for any with matching
identities. So we usually don't have to attempt to verify the signature
with wrong certificates first and can avoid this message.
This took a while as in the OpenSSL package shipped with Debian and on which
our FIPS-enabled package is based, the function SSL_export_keying_material(),
which is used by FreeRADIUS to derive the MSK, did not use the correct digest
to calculate the result when TLS 1.2 was used. This caused IKE to fail with
"verification of AUTH payload with EAP MSK failed". The fix was only
backported to jessie recently.
The main difference is that ping now reports icmp_seq instead of
icmp_req, so we match for icmp_.eq, which works with both releases.
tcpdump now also reports port 4500 as ipsec-nat-t.
ifdown calls bind's rndc, which tries to access TCP port 953 on lo.
If these packets are dropped by the firewall we have to wait for the TCP
connections to time out, which takes quite a while.
With -W we reduce timeouts when we don't expect a response. With -i the
interval between pings is reduced (mostly in case of auto=route where
the first ping yields no reply).
