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32 .Nd "NAT netgraph node type"
38 node performs network address translation (NAT) of packets
44 engine for packet aliasing.
46 This node type has two hooks:
47 .Bl -tag -width ".Va out"
49 Packets received on this hook are considered outgoing and will be
50 masqueraded to a configured address.
52 Packets coming on this hook are considered incoming and will be
56 This node type supports the generic control messages, plus the following:
58 .It Dv NGM_NAT_SET_IPADDR Pq Ic setaliasaddr
59 Configure aliasing address for a node.
60 After both hooks have been connected and aliasing address was configured,
61 a node is ready for aliasing operation.
62 .It Dv NGM_NAT_SET_MODE Pq Ic setmode
63 Set node's operation mode using supplied
64 .Vt "struct ng_nat_mode" .
70 /* Supported flags: */
71 #define NG_NAT_LOG 0x01
72 #define NG_NAT_DENY_INCOMING 0x02
73 #define NG_NAT_SAME_PORTS 0x04
74 #define NG_NAT_UNREGISTERED_ONLY 0x10
75 #define NG_NAT_RESET_ON_ADDR_CHANGE 0x20
76 #define NG_NAT_PROXY_ONLY 0x40
77 #define NG_NAT_REVERSE 0x80
79 .It Dv NGM_NAT_SET_TARGET Pq Ic settarget
80 Configure target address for a node.
81 When an incoming packet not associated with any pre-existing aliasing
82 link arrives at the host machine, it will be sent to the specified address.
83 .It Dv NGM_NAT_REDIRECT_PORT Pq Ic redirectport
84 Redirect incoming connections arriving to given port(s) to
85 another host and port(s).
87 .Vt "struct ng_nat_redirect_port"
88 must be supplied as argument.
90 #define NG_NAT_DESC_LENGTH 64
91 struct ng_nat_redirect_port {
92 struct in_addr local_addr;
93 struct in_addr alias_addr;
94 struct in_addr remote_addr;
99 char description[NG_NAT_DESC_LENGTH];
103 Redirection is assigned an unique ID which is returned as
104 response to this message, and
105 information about redirection added to
106 list of static redirects which later can be retrieved by
107 .Dv NGM_NAT_LIST_REDIRECTS
109 .It Dv NGM_NAT_REDIRECT_ADDR Pq Ic redirectaddr
110 Redirect traffic for public IP address to a machine on the
112 This function is known as
115 .Vt "struct ng_nat_redirect_addr"
116 must be supplied as argument.
118 struct ng_nat_redirect_addr {
119 struct in_addr local_addr;
120 struct in_addr alias_addr;
121 char description[NG_NAT_DESC_LENGTH];
125 Unique ID for this redirection is returned as response to this message.
126 .It Dv NGM_NAT_REDIRECT_PROTO Pq Ic redirectproto
127 Redirect incoming IP packets of protocol
131 to a machine on the local network.
133 .Vt "struct ng_nat_redirect_proto"
134 must be supplied as argument.
136 struct ng_nat_redirect_proto {
137 struct in_addr local_addr;
138 struct in_addr alias_addr;
139 struct in_addr remote_addr;
141 char description[NG_NAT_DESC_LENGTH];
145 Unique ID for this redirection is returned as response to this message.
146 .It Dv NGM_NAT_REDIRECT_DYNAMIC Pq Ic redirectdynamic
147 Mark redirection with specified ID as dynamic, i.e., it will serve
148 for exactly one next connection and then will be automatically
149 deleted from internal links table.
150 Only fully specified links can be made dynamic.
151 The redirection with this ID is also immediately deleted from
152 user-visible list of static redirects (available through
153 .Dv NGM_NAT_LIST_REDIRECTS
155 .It Dv NGM_NAT_REDIRECT_DELETE Pq Ic redirectdelete
156 Delete redirection with specified ID (currently active
157 connections are not affected).
158 .It Dv NGM_NAT_ADD_SERVER Pq Ic addserver
159 Add another server to a pool.
160 This is used to transparently offload network load on a single server
161 and distribute the load across a pool of servers, also known as
165 .Vt "struct ng_nat_add_server"
166 must be supplied as argument.
168 struct ng_nat_add_server {
175 First, the redirection is set up by
176 .Dv NGM_NAT_REDIRECT_PORT
178 .Dv NGM_NAT_REDIRECT_ADDR .
179 Then, ID of that redirection is used in multiple
180 .Dv NGM_NAT_ADD_SERVER
181 messages to add necessary number of servers.
182 For redirections created by
183 .Dv NGM_NAT_REDIRECT_ADDR ,
186 is ignored and could have any value.
187 Original redirection's parameters
191 are also ignored after
192 .Dv NGM_NAT_ADD_SERVER
193 was used (they are effectively replaced by server pool).
194 .It Dv NGM_NAT_LIST_REDIRECTS Pq Ic listredirects
195 Return list of configured static redirects as
196 .Vt "struct ng_nat_list_redirects" .
198 struct ng_nat_listrdrs_entry {
199 uint32_t id; /* Anything except zero */
200 struct in_addr local_addr;
201 struct in_addr alias_addr;
202 struct in_addr remote_addr;
205 uint16_t remote_port;
206 uint16_t proto; /* Valid proto or NG_NAT_REDIRPROTO_ADDR */
207 uint16_t lsnat; /* LSNAT servers count */
208 char description[NG_NAT_DESC_LENGTH];
210 struct ng_nat_list_redirects {
211 uint32_t total_count;
212 struct ng_nat_listrdrs_entry redirects[];
214 #define NG_NAT_REDIRPROTO_ADDR (IPPROTO_MAX + 3)
219 array returned in the unified format for all redirect types.
220 Ports are meaningful only if protocol is either TCP or UDP
223 redirection (created by
224 .Dv NGM_NAT_REDIRECT_ADDR )
228 .Dv NG_NAT_REDIRPROTO_ADDR .
231 servers counter is greater than zero, then
235 are also meaningless.
236 .It Dv NGM_NAT_PROXY_RULE Pq Ic proxyrule
237 Specify a transparent proxying rule (string must be
238 supplied as argument).
242 .It Dv NGM_NAT_LIBALIAS_INFO Pq Ic libaliasinfo
243 Return internal statistics of
246 .Vt "struct ng_nat_libalias_info" .
248 struct ng_nat_libalias_info {
249 uint32_t icmpLinkCount;
250 uint32_t udpLinkCount;
251 uint32_t tcpLinkCount;
252 uint32_t sctpLinkCount;
253 uint32_t pptpLinkCount;
254 uint32_t protoLinkCount;
255 uint32_t fragmentIdLinkCount;
256 uint32_t fragmentPtrLinkCount;
262 failed to retrieve a certain counter
265 instance, the corresponding field is returned as
267 .It Dv NGM_NAT_SET_DLT Pq Ic setdlt
268 Sets the data link type on the
273 Currently, supported types are
275 (raw IP datagrams , no offset applied, the default) and
277 (Ethernet). DLT_ definitions can be found in
279 If you want to work on the
281 level you must use no additional offset by specifying
283 If, however, you attach
285 to a network interface directly and
287 is specified, then the extra offset will be applied to take into account
291 would also inspect appropriate type field in the Ethernet header and
292 pass-through any datagrams that are not IP packets.
293 .It Dv NGM_NAT_GET_DLT Pq Ic getdlt
294 This control message returns the current data link type of the
301 In all redirection messages
305 mean address and port of target machine in the internal network,
309 is zero, then default aliasing address (set by
310 .Dv NGM_NAT_SET_IPADDR )
312 Connections can also be restricted to be accepted only
313 from specific external machines by using non-zero
317 Each redirection assigned an ID which can be later used for
318 redirection manipulation on individual basis (e.g., removal).
319 This ID guaranteed to be unique until the node shuts down
320 (it will not be reused after deletion), and is returned to
321 user after making each new redirection or can be found in
322 the stored list of all redirections.
325 passed to and from node unchanged, together with ID providing
326 a way for several entities to concurrently manipulate
327 redirections in automated way.
329 This node shuts down upon receipt of a
331 control message, or when both hooks are disconnected.
333 In the following example, the packets are injected into a
338 .Bd -literal -offset indent
340 ngctl mkpeer ipfw: nat 60 out
341 ngctl name ipfw:60 nat
342 ngctl connect ipfw: nat: 61 in
343 ngctl msg nat: setaliasaddr x.y.35.8
345 # Divert traffic into NAT node
346 ipfw add 300 netgraph 61 all from any to any in via fxp0
347 ipfw add 400 netgraph 60 all from any to any out via fxp0
349 # Let packets continue with after being (de)aliased
350 sysctl net.inet.ip.fw.one_pass=0
355 node can be inserted right after the
358 In the following example, we perform masquerading on a
359 serial line with HDLC encapsulation.
360 .Bd -literal -offset indent
361 /usr/sbin/ngctl -f- <<-SEQ
362 mkpeer cp0: cisco rawdata downstream
363 name cp0:rawdata hdlc
364 mkpeer hdlc: nat inet in
366 mkpeer nat: iface out inet
367 msg nat: setaliasaddr x.y.8.35
369 ifconfig ng0 x.y.8.35 x.y.8.1
374 node can also be attached directly to the physical interface
378 In the following example, we perform masquerading on a
379 Ethernet interface connected to a public network.
380 .Bd -literal -offset indent
381 ifconfig igb0 inet x.y.8.35 netmask 0xfffff000
382 route add default x.y.0.1
383 /usr/sbin/ngctl -f- <<-SEQ
384 mkpeer igb0: nat lower in
385 name igb0:lower igb0_NAT
386 connect igb0: igb0_NAT: upper out
387 msg igb0_NAT: setdlt 1
388 msg igb0_NAT: setaliasaddr x.y.8.35
400 node type was implemented in
403 .An Gleb Smirnoff Aq Mt glebius@FreeBSD.org