man/man4/ng_macfilter.4

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.Dd December 10, 2018
.Dt NG_MACFILTER 4
.Os
.Sh NAME
.Nm ng_macfilter
.Nd packet filtering netgraph node using ethernet MAC addresses
.Sh SYNOPSIS
.In sys/types.h
.In netgraph/ng_macfilter.h
.Sh DESCRIPTION
The
.Nm macfilter
allows routing ethernet packets over different hooks based on the sender MAC
address.
.Pp
This processing is done when traffic flows from the
.Dq ether
hook through
.Nm macfilter
to one of the outgoing hooks.
Outbound hooks can be added to and remove from
.Nm macfilter
and arbitrarily named.
By default one hook called
.Dq default
is present and used for all packets which have no MAC address in the MAC table.
By adding MAC addresses to the MAC table traffic coming from this host can be
directed out other hooks.
.Nm macfilter
keeps track of packets and bytes from and to this MAC address in the MAC table.
.Pp
Packets are not altered in any way.
If hooks are not connected, packets are
dropped.
.Sh HOOKS
This node type by default has an
.Dv ether
hook, to be connected to the
.Dv lower
hook of the NIC, and a
.Dv default
hook where packets are sent if the MAC adddress is not found in the table.
.Nm macfilter
supports up to
.Dv NG_MACFILTER_UPPER_NUM
hooks to be connected to the NIC's upper hook.
Other nodes can be inserted to provide additional processing.
All outbound can be combined back into one by using
.Dv ng_one2many .
.Sh CONTROL MESSAGES
This node type supports the generic control messages, plus the
following:
.Bl -tag -width foo
.It Dv NGM_MACFILTER_RESET Pq Ic reset
Resets the MAC table in the node.
.It Dv NGM_MACFILTER_DIRECT Pq Ic direct
Takes the following argument struct:
.Bd -literal -offset indent
struct ngm_macfilter_direct {
    u_char	ether[ETHER_ADDR_LEN];  	/* MAC address */
    u_char	hookname[NG_HOOKSIZ];   	/* Upper hook name*/
};
.Ed
The given ethernet MAC address will be forwarded out the named hook.
.It Dv NGM_MACFILTER_DIRECT_HOOKID Pq Ic directi
Takes the following argument struct:
.Bd -literal -offset indent
struct ngm_macfilter_direct_hookid {
    u_char	ether[ETHER_ADDR_LEN];  	/* MAC address */
    u_int16_t	hookid;		        	/* Upper hook hookid */
};
.Ed
The given ethernet MAC address will be forwarded out the hook at id
.Dv hookid .
.It Dv NGM_MACFILTER_GET_MACS Pq Ic getmacs
Returns the list of MAC addresses in the node in the following structure:
.Bd -literal -offset indent
struct ngm_macfilter_mac {
    u_char	ether[ETHER_ADDR_LEN];  	/* MAC address */
    u_int16_t	hookid;		        	/* Upper hook hookid */
    u_int64_t	packets_in;			/* packets in from downstream */
    u_int64_t	bytes_in;			/* bytes in from upstream */
    u_int64_t	packets_out;			/* packets out towards downstream */
    u_int64_t	bytes_out;			/* bytes out towards downstream */
};
struct ngm_macfilter_macs {
    u_int32_t   n;                              /* Number of entries in macs */
    struct ngm_macfilter_mac macs[];            /* Macs table */
};
.Ed
.It Dv NGM_MACFILTER_GETCLR_MACS Pq Ic getclrmacs
Same as above, but will also atomically clear the
.Dv packets_in ,
.Dv bytes_in ,
.Dv packets_out , and
.Dv bytes_out
fields in the table.
.It Dv NGM_MACFILTER_CLR_STATS Pq Ic clrmacs
Will clear the per MAC address packet and byte counters.
.It Dv NGM_MACFILTER_GET_HOOKS Pq Ic gethooks
Will return a list of hooks and their hookids in an array of the following struct's:
.Bd -literal -offset indent
struct ngm_macfilter_hook {
    u_char	hookname[NG_HOOKSIZ];   	/* Upper hook name*/
    u_int16_t	hookid;		        	/* Upper hook hookid */
    u_int32_t   maccnt;                         /* Number of mac addresses associated with hook */
};
.Ed
.El
.Sh SHUTDOWN
This node shuts down upon receipt of a
.Dv NGM_SHUTDOWN
control message or when all have been disconnected.
.Sh EXAMPLES
The following netgraph configuration will apply
.Xr ipfw 8
tag 42 to each packet that is routed over the
.Dq accepted
hook.
The graph looks like the following:
.Bd -literal -offset indent
    /------<one>-[combiner]-<many1>--------\\
<upper>               |                    <out>
  /                <many0>                    \\
[em0]                 |                    [tagger]
  \\               <default>                   /
<lower>               |                     <in>
    \\----<ether>-[macfilter]-<accepted>-----/
.Ed
.Pp
Commands:
.Bd -literal -offset indent
  ngctl mkpeer em0: macfilter lower ether
  ngctl name em0:lower macfilter

  # Funnel both streams back into ether:upper
  ngctl mkpeer em0: one2many upper one
  ngctl name em0:upper recombiner
  # Connect macfilter:default to recombiner:many0
  ngctl connect macfilter: recombiner: default many0
  # Connect macfilter:accepted to tagger:in
  ngctl mkpeer macfilter: tag accepted in
  ngctl name macfilter:accepted tagger
  # Connect tagger:out to recombiner:many1
  ngctl connect tagger: recombiner: out many1

  # Mark tag all traffic through tagger in -> out with an ipfw tag 42
  ngctl msg tagger: sethookin '{ thisHook="in" ifNotMatch="out" }'
  ngctl msg tagger: sethookout '{ thisHook="out" tag_cookie=1148380143 tag_id=42 }'

  # Pass traffic from ether:upper / combiner:one via combiner:many0 on to
  # macfilter:default and on to ether:lower.
  ngctl msg recombiner: setconfig '{ xmitAlg=3 failAlg=1 enabledLinks=[ 1 1 ] }'
.Ed
.Pp
.Em Note :
The tag_cookie 1148380143 was retrieved from
.Dv MTAG_IPFW
in
.Pa /usr/include/netinet/ip_var.h .
.Pp
The following command can be used to add a MAC address to be output via
.Dv macfilter:accepted :
.Bd -literal -offset indent
  ngctl msg macfilter: direct '{ hookname="known" ether=08:00:27:92:eb:aa }'
.Ed
.Pp
The following command can be used to retrieve the packet and byte counters :
.Bd -literal -offset indent
  ngctl msg macfilter: getmacs
.Ed
.Pp
It will return the contents of the MAC table:
.Bd -literal -offset indent
  Rec'd response "getmacs" (4) from "[54]:":
  Args:	{ n=1 macs=[ { ether=08:00:27:92:eb:aa hookid=1 packets_in=3571 bytes_in=592631 packets_out=3437 bytes_out=777142 } ] }
.Ed
.Sh SEE ALSO
.Xr divert 4 ,
.Xr ipfw 4 ,
.Xr netgraph 4 ,
.Xr ng_ether 4 ,
.Xr ng_one2many 4 ,
.Xr ng_tag 4 ,
.Xr ngctl 8
.Sh AUTHORS
.An -nosplit
The original version of this code was written by Pekka Nikander, and
subsequently modified heavily by
.An Nick Hibma Aq Mt n_hibma@FreeBSD.org .
.Sh BUGS
None known.