diff --git a/examples/route_hi.rb b/examples/route_hi.rb
index 8d08a5e..cca0f33 100644
--- a/examples/route_hi.rb
+++ b/examples/route_hi.rb
@@ -16,7 +16,7 @@ pp rt.links["eth0"]
 puts "\nAddresses on interface eth0:"
 pp rt.addrs.list(:index=>"eth0").to_a
 
-puts "\nAll routes in main routing table:"
+puts "\nAll v4 routes in main routing table:"
 pp rt.routes.list(:family=>Socket::AF_INET, :table=>Netlink::RT_TABLE_MAIN).to_a
 
 puts "\nDefault route is probably:"
diff --git a/lib/netlink/route/addr_handler.rb b/lib/netlink/route/addr_handler.rb
index a87c029..1d0aada 100644
--- a/lib/netlink/route/addr_handler.rb
+++ b/lib/netlink/route/addr_handler.rb
@@ -1,4 +1,5 @@
 require 'netlink/route'
+require 'netlink/route/handler'
 
 module Netlink
   # struct ifa_cacheinfo
@@ -25,28 +26,12 @@ module Netlink
   end
 
   module Route
-    # This class provides an API for manipulating interfaces and addresses.
-    # Since we frequently need to map ifname to ifindex, or vice versa,
-    # we keep a memoized list of interfaces. If the interface list changes,
-    # you should create a new instance of this object.
-    class AddrHandler
-      def initialize(rtsocket = Netlink::Route::Socket.new)
-        @rtsocket = rtsocket
-        clear_cache
-      end
-
+    # This class provides an API for manipulating iaddresses.
+    class AddrHandler < Handler
       def clear_cache
         @addrs = nil
       end
-
-      def index(v)
-        @rtsocket.index(v)
-      end
-
-      def ifname(v)
-        @rtsocket.ifname(v)
-      end
-                  
+      
       # Download a list of link addresses. Either returns an array of
       # Netlink::IFAddr objects, or yields them to the supplied block.
       # You will need to use the 'index' to cross reference to the interface.
@@ -65,6 +50,14 @@ module Netlink
         @rtsocket.receive_until_done(RTM_NEWADDR, &blk)
       end
 
+      class Filter < BaseFilter #:nodoc:
+        filter(:family) { |o,v| o.family == v }
+        filter(:scope) { |o,v| o.scope == scope }
+        filter(:flags) { |o,v| (o.flags & v) == v }
+        filter(:noflags) { |o,v| (o.flags & v) == 0 }
+        filter(:index) { |o,v| o.index == v }
+      end
+      
       # Iterate over all addresses, or addressees matching the given
       # criteria. Returns an Enumerator if no block given.
       #
@@ -74,20 +67,10 @@ module Netlink
       #    nl.addrs.list { |x| p x }
       #    addrs_eth0 = nl.addrs.list(:index=>"eth0").to_a
       #    addrs_eth0_v4 = nl.addrs.list(:index=>"eth0", :family=>Socket::AF_INET).to_a
-      #
-      # TODO: error on unknown filter conditions
       def list(filter=nil, &blk)
         @addrs ||= read_addrs
-        return @addrs.each(&blk) unless filter
-        return to_enum(:list, filter) unless block_given?
-        filter[:index] = index(filter[:index]) if filter.has_key?(:index)
-        @addrs.each do |o|
-          yield o if (!filter[:family] || o.family == filter[:family]) &&
-          (!filter[:scope] || o.kind?(filter[:scope])) &&
-          (!filter[:flags] || (o.flags & filter[:flags]) == filter[:flags]) &&
-          (!filter[:noflags] || (o.flags & filter[:noflags]) == 0) &&
-          (!filter[:index] || o.index == filter[:index])
-        end
+        filter[:index] = index(filter[:index]) if filter && filter.has_key?(:index)
+        do_list(@addrs, filter, &blk)
       end
       alias :each :list
       
diff --git a/lib/netlink/route/handler.rb b/lib/netlink/route/handler.rb
new file mode 100644
index 0000000..79c0fc8
--- /dev/null
+++ b/lib/netlink/route/handler.rb
@@ -0,0 +1,46 @@
+module Netlink
+  module Route
+    # This class allows objects to be created representing the
+    # conditions given to the 'list' method
+    class BaseFilter #:nodoc:
+      def self.filter name, &blk
+        define_method "#{name}=" do |matchval|
+          @conds << [blk, matchval]
+        end
+      end
+      
+      def initialize(h)
+        @conds = []
+        h.each { |k,v| send "#{k}=", v }
+      end
+      
+      def match(obj)
+        !@conds.find { |blk,matchval| !blk[obj,matchval] }
+      end
+    end
+
+    # Code which is common to all the NETLINK_ROUTE handlers
+    class Handler
+      def initialize(rtsocket = Netlink::Route::Socket.new)
+        @rtsocket = rtsocket
+        clear_cache
+      end
+      
+      def index(v)
+        @rtsocket.index(v)
+      end
+      
+      def ifname(v)
+        @rtsocket.ifname(v)
+      end
+
+      # Generic listing and filtering
+      def do_list(data, filter, &blk)
+        return data.each(&blk) unless filter
+        return to_enum(:list, filter) unless block_given?
+        fm = self.class::Filter.new(filter)
+        data.each { |o| yield o if fm.match(o) }
+      end
+    end
+  end
+end
diff --git a/lib/netlink/route/link_handler.rb b/lib/netlink/route/link_handler.rb
index ddf5530..f8757ff 100644
--- a/lib/netlink/route/link_handler.rb
+++ b/lib/netlink/route/link_handler.rb
@@ -1,4 +1,5 @@
 require 'netlink/route'
+require 'netlink/route/handler'
 
 module Netlink
   # struct rtnl_link_stats / rtnl_link_stats64
@@ -119,21 +120,12 @@ module Netlink
     # Since we frequently need to map ifname to ifindex, or vice versa,
     # we keep a memoized list of interfaces. If the interface list changes,
     # you should create a new instance of this object.
-    class LinkHandler
-      def initialize(rtsocket = Netlink::Route::Socket.new)
-        @rtsocket = rtsocket
-        clear_cache
-      end
-
+    class LinkHandler < Handler
       def clear_cache
         @links = nil
         @linkmap = nil
       end
 
-      def index(v)
-        @rtsocket.index(v)
-      end
-            
       # Download a list of links (interfaces). Either returns an array of
       # Netlink::IFInfo objects, or yields them to the supplied block.
       #
@@ -150,7 +142,15 @@ module Netlink
                      NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST
         @rtsocket.receive_until_done(RTM_NEWLINK, &blk)
       end
-
+      
+      class Filter < BaseFilter #:nodoc:
+        filter(:type) { |o,v| o.type == v }
+        filter(:kind) { |o,v| o.kind?(v) }
+        filter(:flags) { |o,v| (o.flags & v) == v }
+        filter(:noflags) { |o,v| (o.flags & v) == 0 }
+        filter(:link) { |o,v| o.link == v }
+      end
+      
       # Iterate over all interfaces, or interfaces matching the given
       # criteria. Returns an Enumerator if no block given.
       #
@@ -165,16 +165,8 @@ module Netlink
       #    rt.links.list(:link => "lo")   # vlan etc attached to this interface
       def list(filter=nil, &blk)
         @links ||= read_links
-        return @links.each(&blk) unless filter
-        return to_enum(:list, filter) unless block_given?
-        filter[:link] = index(filter[:link]) if filter.has_key?(:link)
-        @links.each do |o|
-          yield o if (!filter[:type] || o.type == filter[:type]) &&
-          (!filter[:kind] || o.kind?(filter[:kind])) &&
-          (!filter[:flags] || (o.flags & filter[:flags]) == filter[:flags]) &&
-          (!filter[:noflags] || (o.flags & filter[:noflags]) == 0) &&
-          (!filter[:link] || o.link == filter[:link])
-        end
+        filter[:link] = index(filter[:link]) if filter && filter.has_key?(:link)
+        do_list(@links, filter, &blk)
       end
       alias :each :list
             
diff --git a/lib/netlink/route/route_handler.rb b/lib/netlink/route/route_handler.rb
index b2794fa..7b89576 100644
--- a/lib/netlink/route/route_handler.rb
+++ b/lib/netlink/route/route_handler.rb
@@ -1,4 +1,5 @@
 require 'netlink/route'
+require 'netlink/route/handler'
 
 module Netlink
   # struct rta_cacheinfo
@@ -47,20 +48,11 @@ module Netlink
 
   module Route
     # This class manipulates the kernel routing table
-    class RouteHandler
-      def initialize(rtsocket = Netlink::Route::Socket.new)
-        @rtsocket = rtsocket
-        clear_cache
-      end
-      
+    class RouteHandler < Handler
       def clear_cache
         @routes = nil
       end
       
-      def index(v)
-        @rtsocket.index(v)
-      end
-      
       # Send message to download the kernel routing table. Either returns an
       # array of Netlink::RT objects, or yields them to the supplied block.
       #
@@ -88,6 +80,18 @@ module Netlink
         @rtsocket.receive_until_done(RTM_NEWROUTE, &blk)
       end
 
+      class Filter < BaseFilter #:nodoc:
+        filter(:family) { |o,v| o.family == v }
+        filter(:table) { |o,v| o.table == v }
+        filter(:protocol) { |o,v| o.protocol == v }
+        filter(:type) { |o,v| o.type == v }
+        filter(:scope) { |o,v| o.scope == v }
+        filter(:flags) { |o,v| (o.flags & v) == v }
+        filter(:noflags) { |o,v| (o.flags & v) == 0 }
+        filter(:oif) { |o,v| o.oif == v }
+        filter(:iif) { |o,v| o.iif == v }
+      end
+      
       # Return the memoized route table, filtered according to
       # the optional criteria. Examples:
       #    :family => Socket::AF_INET
@@ -100,22 +104,10 @@ module Netlink
       #    :oif => "eth0"
       #    :iif => "eth1"
       def list(filter=nil, &blk)
-        @routes = read_routes
-        return @routes.each(&blk) unless filter
-        return to_enum(:list, filter) unless block_given?
-        filter[:oif] = index(filter[:oif]) if filter.has_key?(:oif)
-        filter[:iif] = index(filter[:iif]) if filter.has_key?(:iif)
-        @routes.each do |o|
-          yield o if (!filter[:family] || o.family == filter[:family]) &&
-          (!filter[:table] || o.table == filter[:table]) &&
-          (!filter[:protocol] || o.protocol == filter[:protocol]) &&
-          (!filter[:type] || o.scope == filter[:protocol]) &&
-          (!filter[:scope] || o.type == filter[:type]) &&
-          (!filter[:flags] || (o.flags & filter[:flags]) == filter[:flags]) &&
-          (!filter[:noflags] || (o.flags & filter[:noflags]) == 0) &&
-          (!filter[:oif] || o.oif == filter[:oif]) &&
-          (!filter[:iif] || o.iif == filter[:iif])
-        end
+        @routes ||= read_routes
+        filter[:oif] = index(filter[:oif]) if filter && filter.has_key?(:oif)
+        filter[:iif] = index(filter[:iif]) if filter && filter.has_key?(:iif)
+        do_list(@routes, filter, &blk)
       end
       alias :each :list
       
diff --git a/lib/netlink/route/vlan_handler.rb b/lib/netlink/route/vlan_handler.rb
index a9538ab..05c9a4f 100644
--- a/lib/netlink/route/vlan_handler.rb
+++ b/lib/netlink/route/vlan_handler.rb
@@ -1,14 +1,11 @@
 require 'netlink/route'
+require 'netlink/route/handler'
 
 module Netlink
   module Route
-    class VlanHandler
-      def initialize(rtsocket = Netlink::Route::Socket.new)
-        @rtsocket = rtsocket
-      end
-      
-      def index(v)
-        @rtsocket.index(v)
+    class VlanHandler < Handler
+      def clear_cache
+        # No cache
       end
       
       def list(filter={}, &blk)