174 lines
6.9 KiB
Plaintext
174 lines
6.9 KiB
Plaintext
# $FreeBSD$
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#
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# This is an example that shows how to send ASCII formatted control
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# messages to a node using ngctl(8).
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#
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# What we will do here create a divert(4) tap. This simply dumps
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# out all packets diverted by some ipfw(8) divert rule to the console.
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#
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# Lines that begin with ``$'' (shell prompt) or ``+'' (ngctl prompt)
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# indicate user input
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#
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# First, start up ngctl in interactive mode:
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$ ngctl
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Available commands:
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connect Connects hook <peerhook> of the node at <relpath> to <hook>
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debug Get/set debugging verbosity level
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help Show command summary or get more help on a specific command
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list Show information about all nodes
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mkpeer Create and connect a new node to the node at "path"
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msg Send a netgraph control message to the node at "path"
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name Assign name <name> to the node at <path>
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read Read and execute commands from a file
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rmhook Disconnect hook "hook" of the node at "path"
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show Show information about the node at <path>
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shutdown Shutdown the node at <path>
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status Get human readable status information from the node at <path>
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types Show information about all installed node types
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quit Exit program
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+
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# Now let's create a ng_ksocket(4) node, in the family PF_INET,
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# of type SOCK_RAW, and protocol IPPROTO_DIVERT:
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+ mkpeer ksocket foo inet/raw/divert
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# Note that ``foo'' is the hook name on the socket node, which can be
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# anything. The ``inet/raw/divert'' is the hook name on the ksocket
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# node, which tells it what kind of socket to create.
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# Lets give our ksocket node a global name. How about ``fred'':
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+ name foo fred
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# Note that we used ngctl's ``name'' command to do this. However,
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# the following manually constructed netgraph message would have
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# acomplished the exact same thing:
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+ msg foo name { name="fred" }
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# Here we are using the ASCII <-> binary control message conversion
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# routines. ngctl does this for us automatically when we use the
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# ``msg'' command.
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# Now lets bind the socket associated with the ksocket node to a port
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# supplied by the system. We do this by sending the ksocket node a
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# ``bind'' control message. Again, ngctl does the conversion of the
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# control message from ASCII to binary behind the scenes.
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+ msg fred: bind inet/192.168.1.1
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# The ksocket accepts arbitrary sockaddr structures, but also has
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# special support for the PF_LOCAL and PF_INET protocol families.
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# That is why we can specify the struct sockaddr argument to the
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# ``bind'' command as ``inet/192.168.1.1'' (since we didn't specify
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# a port number, it's assumed to be zero). We could have also
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# relied on the generic sockaddr syntax and instead said this:
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+ msg fred: bind { family=2 len=16 data=[ 2=192 168 1 1 ] }
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# This is what you would have to do for protocol families other
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# that PF_INET and PF_LOCAL, at least until special handling for
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# new ones is added.
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# The reason for the ``2=192'' is to skip the two byte IP port number,
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# which causes it to be set to zero, the default value for integral
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# types when parsing. Now since we didn't ask for a specific port
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# number, we need to do a ``getname'' to see what port number we got:
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+ msg fred: getname
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Rec'd response "getname" (5) from "fred:":
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Args: inet/192.168.1.1:1029
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# As soon as we sent the message, we got back a response. Here
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# ngctl is telling us that it received a control message with the
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# NGF_RESP (response) flag set, the reponse was to a prior ``getname''
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# control message, that the originator was the node addressable
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# as ``fred:''. The message arguments field is then displayed to
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# us in its ASCII form. In this case, what we get back is a struct
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# sockaddr, and there we see that our port number is 1029.
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# So now let's add the ipfw divert rule for whatever packets we
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# want to see. How about anything from 192.168.1.129.
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+ ^Z
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Suspended
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$ ipfw add 100 divert 1029 ip from 192.168.1.129 to any
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00100 divert 1029 ip from 192.168.1.129 to any
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$ fg
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# Now watch what happens when we try to ping from that machine:
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+
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Rec'd data packet on hook "foo":
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0000: 45 00 00 3c 57 00 00 00 20 01 bf ee c0 a8 01 81 E..<W... .......
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0010: c0 a8 01 01 08 00 49 5c 03 00 01 00 61 62 63 64 ......I\....abcd
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0020: 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70 71 72 73 74 efghijklmnopqrst
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0030: 75 76 77 61 62 63 64 65 66 67 68 69 uvwabcdefghi
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+
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Rec'd data packet on hook "foo":
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0000: 45 00 00 3c 58 00 00 00 20 01 be ee c0 a8 01 81 E..<X... .......
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0010: c0 a8 01 01 08 00 48 5c 03 00 02 00 61 62 63 64 ......H\....abcd
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0020: 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70 71 72 73 74 efghijklmnopqrst
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0030: 75 76 77 61 62 63 64 65 66 67 68 69 uvwabcdefghi
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+
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Rec'd data packet on hook "foo":
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0000: 45 00 00 3c 59 00 00 00 20 01 bd ee c0 a8 01 81 E..<Y... .......
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0010: c0 a8 01 01 08 00 47 5c 03 00 03 00 61 62 63 64 ......G\....abcd
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0020: 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70 71 72 73 74 efghijklmnopqrst
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0030: 75 76 77 61 62 63 64 65 66 67 68 69 uvwabcdefghi
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+
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# So we're seeing the output from the ksocket socket appear on the ``foo''
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# hook of ngctl's socket node. Since the packets are getting diverted,
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# the 192.168.1.129 machine doesn't see any response from us.
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# Of course, any type of socket can be used, even TCP:
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+ mkpeer ksocket bar inet/stream/tcp
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+ msg bar connect inet/192.168.1.33:13
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ngctl: send msg: Operation now in progress
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+
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Rec'd data packet on hook "foo":
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0000: 4d 6f 6e 20 4e 6f 76 20 32 39 20 31 37 3a 34 38 Mon Nov 29 17:48
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0010: 3a 33 37 20 31 39 39 39 0d 0a :37 1999..
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+
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# Or, UNIX domain:
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+ mkpeer ksocket bar local/stream/0
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+ msg bar bind local/"/tmp/bar.socket"
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+
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# Here's an example of a more complicated ASCII control message argument.
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# If you look in /sys/netgraph/ng_message.h, you will see that a node
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# responds to a NGM_LISTHOOKS with a struct hooklist, which contains
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# an array of struct linkinfo:
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#
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# /* Structure used for NGM_LISTHOOKS */
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# struct linkinfo {
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# char ourhook[NG_HOOKLEN + 1]; /* hook name */
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# char peerhook[NG_HOOKLEN + 1]; /* peer hook */
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# struct nodeinfo nodeinfo;
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# };
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#
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# struct hooklist {
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# struct nodeinfo nodeinfo; /* node information */
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# struct linkinfo link[0]; /* info about each hook */
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# };
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#
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# By sending a node the ``listhooks'' command using ngctl, we can see
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# this structure in ASCII form (lines wrapped for readability):
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+ msg bar bind local/"/tmp/bar.socket"
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+ msg bar listhooks
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Rec'd response "listhooks" (7) from "bar":
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Args: { nodeinfo={ type="ksocket" id=9 hooks=1 }
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linkinfo=[ { ourhook="local/stream/0" peerhook="bar"
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nodeinfo={ name="ngctl1327" type="socket" id=8 hooks=1 } } ] }
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