Some changes related to logging

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
GANETI_INSTANCE_NAME -> INSTANCE

GANETI_INSTANCE_NAME is available only in hooks. Library uses
INSTANCE so we should set it as soon as possible.

Hooks are not aware of INTERFACE. Thus get_info() will find
INDEV and ebtables chains only during NIC configuration scripts.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Move reset_dns() in common.sh

Note that currently this is executed only during
OP_INSTANCE_SET_PARAMS.

Before using it we should query_dns().

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Support firewall for bridged setups

Just like routed setups we parse instance's tags and search
for a specific suffix (chain). If found we add an ebtables
rule so that outgoing traffic to tap will go through this
chain.

Note that those chains should be created by admin first.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Add snf-network.ferm for firewalls

This ferm defines 3 extra chains in filter table (for both
ipv4 and ipv6): protected, limited, unprotected.

The first drops incoming new connections, allows dns replies and pings.
The seconds allows ssh, and rdp ports.
The third just accepts the packet.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Update docs

- ifup-extra
- firewall
- nfdhcpd

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Change interfaces example file

Use addresses reserved for documentation in interfaces example file.

Mention two setups:

 * routed setup
    - external router
    - nodes without IP inside routed network
    - proxy ARP

 * bridged setup
    - extra common interfaces on all nodes
    - one common bridge on separate interface
    - node with internet access is the gateway and does NAT

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Update docs wrt ip-less-routed setup

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Create examples dir

..and add interfaces, vmrouter ifup and ifdown scripts, and
prv-net-helper.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Add separate docs for routed and ebtables setup

Remove further info and implementation details of ip-less-routed
and private-filtered setups from main page. Introduce routed and
ebtables page to include all this info.

Add /etc/network/interfaces examples for ip-less-routed
configuration.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>