X-Git-Url: https://git.proxmox.com/?p=pve-firewall.git;a=blobdiff_plain;f=README;h=c1c2518e0603166a02c4d838c3bceeff0d8324d6;hp=41c7c199456b519b29f5da22483986a5747d9315;hb=3a616aa0ae97f3dc0fd3faa0361d5c4e8b3b312f;hpb=5e1267a55ed38388206bc1116b7b68775e8caf72

diff --git a/README b/README
index 41c7c19..c1c2518 100644
--- a/README
+++ b/README
@@ -1,4 +1,5 @@
-Experimental software, only used for testing.
+Experimental software, only used for testing!
+=============================================
 
 Note: you need to change values in /etc/sysctl.d/pve.conf to:
 
@@ -9,6 +10,8 @@ net.bridge.bridge-nf-filter-vlan-tagged = 1
 
 and reboot after that change.
 
+Quick Intro
+===========
 
 VM firewall rules are read from /etc/pve/firewall/<VMID>.fw
 
@@ -35,4 +38,110 @@ To stop the firewall:
 
 To clear all iptable rules:
 
-./pvefw clear
\ No newline at end of file
+./pvefw clear
+
+
+Implementation details
+======================
+
+We do not write iptables rules directly. Instead we use shorewall to
+do that low level stuff. 
+
+Each VM can have its own firewall definition file in 
+
+/etc/pve/firewall/<VMID>.fw
+
+That file has two sections for inbound [IN] and outbound [OUT] traffic.
+
+Format is: ACTION IFACE SOURCE DEST PROTO D-PORT S-PORT
+
+* ACTION: shorewall action
+* IFACE: vm network interface (net0 - net5), or '-' for all interfaces
+* SOURCE: source IP address, or '-' for any source
+* DEST: dest IP address, or '-' for any destination address
+* PROTO: see /etc/protocols
+* D-PORT: destination port
+* S-PORT: source port
+
+We translate those rules into an appropriate shorewall configuration.
+
+There are a number of restrictions when using iptables to filter
+bridged traffic. Shorewall reflects that by applying the following
+restrictions:
+
+* BP zones may only be associated with bridge ports.
+
+* All ports associated with a given BP zone must be on the same bridge.
+
+* Policies from a non-BP zone to a BP are disallowed.
+
+* Rules where the SOURCE is a non-BP zone and the DEST is a BP zone are disallowed.
+
+See: http://www.shorewall.net/bridge-Shorewall-perl.html
+
+We simply define one zone for each bridge/vm pair.
+
+Shorewall zones names are limited to 5 characters, so we need to
+translate our names into shorter ones. The mapping is store in
+/etc/shorewall/params, so we can use shell variables with long names
+to refer to those zones.
+
+Example: One bridge vmbr0 and one VM with id 100
+
+Content of /etc/shorewall/params
+ # PVE zones
+ FW=fw
+ ZVMBR0=z0
+ ZVMBR0EXT=z1
+ ZVMBR0VM100=z2
+
+Content of /etc/shorewall/zones 
+ #ZONE                          TYPE       OPTIONS        
+ $FW                            firewall                  
+ $ZVMBR0                        ipv4                      
+ $ZVMBR0EXT:$ZVMBR0             bport                     
+ $ZVMBR0VM100:$ZVMBR0           bport                     
+ #LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
+
+Content of /etc/shorewall/interfaces
+ #ZONE                     INTERFACE            BROADCAST  OPTIONS        
+ $ZVMBR0                   vmbr0                detect     bridge,optional
+ $ZVMBR0EXT                vmbr0:eth0           -                         
+ $ZVMBR0VM100              vmbr0:tap100i0       -          maclist        
+ #LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE
+
+Zone $ZVMBR0VM100 contains all network interfaces from VM100.
+
+Zone $ZVMBR0EXT contains all physical network interfaces. We consider this zone to be the external world.
+
+A shorewall rule for inbound traffic looks like this:
+
+ SSH(ACCEPT)     all       $ZVMBR0VM100:tap100i0 
+
+Outbound rules looks like:
+
+ SSH(ACCEPT)     $ZVMBR0VM100:tap100i0          all
+
+
+Problems
+===================
+
+Inbound rules with source IP does not work, because shorewall
+does not allow rules like:
+
+ SSH(ACCEPT)     all:IP_ADDRESS       $ZVMBR0VM100:tap100i0
+
+As workaroud, we create one rule for each BP zone on the same
+bridge:
+
+ SSH(ACCEPT)     $ZVMBR0:IP_ADDRESS       $ZVMBR0VM100:tap100i0
+ SSH(ACCEPT)     $ZVMBR0VM777:IP_ADDRESS  $ZVMBR0VM100:tap100i0
+ SSH(ACCEPT)     $ZVMBR0EXT:IP_ADDRESS    $ZVMBR0VM100:tap100i0
+
+
+
+
+
+
+
+