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Extending the firewall documentation regarding standard rules and logging

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Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
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Christian Ebner 2019-03-25 10:30:14 +01:00 committed by Thomas Lamprecht
parent 7d6078845f
commit afde3bac8c
1 changed files with 110 additions and 13 deletions
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pve-firewall.adoc
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@ -404,28 +404,125 @@ If you want to see the generated iptables rules you can use:
# iptables-save
[[pve_firewall_default_rules]]
Default firewall rules
----------------------
The following traffic is filtered by the default firewall configuration:
Datacenter incomming/outgoing DROP/REJECT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If the input/output policy for the firewall is set to DROP/REJECT, the following
traffic is still allowed for the host:
* traffic over the loopback interface
* already established connections
* traffic using the igmp protocol
* tcp traffic from management hosts to port 8006 in order to allow access to
the web interface
* tcp traffic from management hosts to the port range 5900 to 5999 allowing
traffic for the VNC web console
* tcp traffic from management hosts to port 3128 for connections to the SPICE
proxy
* tcp traffic from management hosts to port 22 to allow ssh access
* udp traffic in the cluster network to port 5404 and 5405 for corosync
* udp multicast traffic in the cluster network
* icmp traffic type 3,4 or 11
The following traffic is dropped, but not logged even with logging enabled:
* tcp connections with invalid connection state
* Broad-, multi- and anycast traffic not related to corosync
* tcp traffic to port 43
* udp traffic to ports 135 and 445
* udp traffic to the port range 137 to 139
* udp traffic form source port 137 to port range 1024 to 65535
* udp traffic to port 1900
* tcp traffic to port 135, 139 and 445
* udp traffic originating from source port 53
The rest of the traffic is dropped/rejected and logged.
This may vary depending on the additional options enabled in
*Firewall* -> *Options*, such as NDP, SMURFS and TCP flag filtering.
Please inspect the output of
# iptables-save
to see the firewall chains and rules active on your system.
VM/CT incomming/outgoing DROP/REJECT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This drops/rejects all the traffic to the VMs, with some exceptions for DHCP, NDP,
Router Advertisement, MAC and IP filtering depending on the set configuration.
The same rules for dropping/rejecting packets are inherited from the datacenter,
while the exceptions for accepted incomming/outgoing traffic of the host do not
apply.
Again, please inspect the output of
# iptables-save
to see in detail the firewall chains and rules active for the VMs/CTs.
Logging of firewall rules
-------------------------
By default, logging of traffic filtered by the firewall rules is disabled. To
enable logging for the default firewall rules, the log-level for incommig and
outgoing traffic has to be set in the firewall `Options` tab for the host and/or
the VM/CT firewall.
Logging of dropped packets is rate limited to 1 packet per second in order to
reduce output to the log file.
Further, only some dropped or rejected packets are logged for the standard rules.
By default, all logging of traffic filtered by the firewall rules is disabled.
To enable logging, the `loglevel` for incommig and/or outgoing traffic has to be
set in *Firewall* -> *Options*. This can be done for the host as well as for the
VM/CT firewall individually. By this, logging of {PVE}'s standard firewall rules
is enabled and the output can be observed in *Firewall* -> *Log*.
Further, only some dropped or rejected packets are logged for the standard rules
(see xref:pve_firewall_default_rules[default firewall rules]).
// TODO: describe standard/default rules and note which of them get logged
`loglevel` does not affect how much of the filtered traffic is logged. It
changes a `LOGID` appended as prefix to the log output for easier filtering and
post-processing.
`loglevel` is one of the following flags:
[[pve_firewall_log_levels]]
[width="25%", options="header"]
|===================
| loglevel | LOGID
| nolog | no log
| emerg | 0
| alert | 1
| crit | 2
| err | 3
| warning | 4
| notice | 5
| info | 6
| debug | 7
|===================
A typical firewall log output looks like this:
----
VMID LOGID CHAIN TIMESTAMP POLICY: PACKET_DETAILS
----
In case of the host firewall, `VMID` is equal to 0.
Logging of user defined firewall rules
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In order to log packets filtered by user-defined firewall rules, it is possible
to set a log-level parameter for each rule individually.
This allows to log in a fine grained manner and independent of the log-level
defined for the standard rules in the firewall `Options`.
defined for the standard rules in *Firewall* -> *Options*.
The log level for the rule can also be set via the firewall configuration file by
appending a `-log <loglevel>` to the selected rule.
Here, `<loglevel>` is one of the following flags:
`nolog, emerg, alert, crit, err, warning, notice, info, debug`
While the `loglevel` for each individual rule can be defined or changed easily
in the WebUI during creation or modification of the rule, it is possible to set
this also via the corresponding `pvesh` API calls.
Further, the log-level can also be set via the firewall configuration file by
appending a `-log <loglevel>` to the selected rule (see
xref:pve_firewall_log_levels[possible log-levels]).
For example, the following two are ident: