1DNET(8) BSD System Manager's Manual DNET(8)
2
4 dnet — dumb networking library test program
5
7 dnet command args [...]
8
10 dnet is a simple test program for the dnet(3) library. It can be used to
11 compose and transmit network datagrams as a Unix-style filter (e.g. read‐
12 ing from or writing to files and pipes) or modify the local system net‐
13 work configuration (including the ARP cache, firewall ruleset, network
14 interfaces, and routing table).
15 Payload generation commands
17 addr address [...]
18 Convert the address (specified as a hostname, IP address, or MAC ad‐
19 dress) into its binary representation on standard output.
20 hex string [...]
22 Convert the C-style escaped string (shellcode, for instance) into
23 its binary representation on standard output.
24 rand len
26 Write len random bytes to standard output.
27 Packet encapsulation commands
29 eth [type type] [src mac] [dst mac]
30 Prepend the data read from standard input with an Ethernet header on
31 standard output. The Ethernet type may be specified as ‘arp’, ‘ip’,
32 or as a hex, octal, or decimal number.
33 arp [op op] [sha mac] [spa host] [tha mac] [tpa host]
35 Prepend the data read from standard input with an ARP header on
36 standard output. The ARP op may be specified as ‘req’, ‘rep’,
37 ‘revreq’, ‘revrep’, or as a hex, octal, or decimal number.
38 ip [tos num] [id num] [off offset] [ttl num] [proto protocol] [src host]
40 [dst dst]
41 Prepend the data read from standard input with an IP header on stan‐
42 dard output. The fragmentation offset may be specified as a decimal
43 number (optionally concatenated with ‘+’ to indicate more fragments)
44 or as a hex number. The protocol may be specified by name, or as a
45 hex, octal, or decimal number.
46 icmp [type num] [code num]
48 Prepend the data read from standard input with an ICMP header on
49 standard output.
50 tcp [sport port] [dport port] [flags flags] [seq num] [ack num] [win num]
52 [urp num]
53 Prepend the data read from standard input with a TCP header on stan‐
54 dard output. A port may be specified by name or hex, octal, or deci‐
55 mal number. The TCP flags may be specified as some combination of
56 the characters in the set ‘SAFRPU’ or as a hex number.
57 udp [sport port] [dport port]
59 Prepend the data read from standard input with a UDP header on stan‐
60 dard output. A port may be specified by name or hex, octal, or deci‐
61 mal number.
62 Packet transmission commands
64 send [device]
65 Read a packet from standard input and send it over the network. If
66 no device is specified, the packet is assumed to be an IP datagram
67 and routed to its destination. Otherwise, the packet is assumed to
68 be an Ethernet frame and is transmitted on the specified interface.
69 Kernel interface commands
71 arp show
72 Display the kernel ARP cache.
73 arp get host
75 Display the kernel ARP entry for host.
76 arp add host mac
78 Add an ARP entry mapping the mac address for host.
79 arp delete host
81 Delete the ARP entry for host.
82 fw show
84 Display the kernel firewall ruleset.
85 fw add|delete action direction device protocol src[:port[-max]]
87 dst[:port[-max]] [type[/code]]
88 Add a rule to or delete a rule from the active firewall ruleset. The
89 action must be either ‘allow’ or ‘block’. The direction must be ei‐
90 ther ‘in’ or ‘out’. The device may specify an interface name, or
91 ‘any’. The protocol may be specified by name, or as a decimal num‐
92 ber. For TCP and UDP protocols, a port (or range, if specified with
93 a max value) may be specified in decimal and appended to the source
94 and/or destination address. For ICMP, a type (and optional code) may
95 be specified in decimal.
96 intf show
98 Display the configuration of all network interfaces.
99 intf get device
101 Display the configuration for the interface specified by device.
102 intf set device [alias host] [dst host] [inet host] [link mac] [up|down]
104 [arp|noarp]
105 Configure the interface specified by device.
106 route show
108 Display the kernel routing table.
109 route get dst
111 Display the route for the destination dst, specified as a hostname,
112 IP address, or network prefix in CIDR notation.
113 route add dst gw
115 Add a route for the destination dst through the gateway gw.
116 route delete dst
118 Delete the route for the destination dst.
119
121 Send a UDP datagram containing random shellcode:
122 dnet hex "\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89" \
124 "\x46\x0c\xb0\x0b\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80" \
125 "\x31\xdb\x89\xd8\x40\xcd\x80\xe8\xdc\xff\xff\xff/bin/sh" | \
126 dnet udp sport 555 dport 666 | \
127 dnet ip proto udp src 1.2.3.4 dst 5.6.7.8 | dnet send
128 Save an ARP request in a file and send it twice:
130 dnet arp op req sha 0:d:e:a:d:0 spa 10.0.0.3 tpa 10.0.0.4 | \
132 dnet eth type arp src 0:d:e:a:d:0 dst ff:ff:ff:ff:ff:ff > arp.pkt
133 dnet send fxp0 < arp.pkt
134 dnet send fxp0 < arp.pkt
135 Send a fragmented ping packet:
137 # Create ping packet with IP header, to set ICMP checksum
139 echo "monkey monkey monkey monkey" | dnet icmp type 8 code 0 | \
140 dnet ip proto icmp src 1.2.3.4 dst 5.6.7.8 > ping.pkt
141 # Chop off IP header
143 dd if=ping.pkt of=ping.data bs=20 skip=1
144 # Fragment IP payload
146 split -b 24 ping.data p.
147 # Send fragments
149 dnet ip id 1 off 0+ proto icmp src 1.2.3.4 dst 5.6.7.8 < p.aa | \
150 dnet send
151 dnet ip id 1 off 24 proto icmp src 1.2.3.4 dst 5.6.7.8 < p.ab | \
152 dnet send
153
155 dnet(3)
156
158 Dug Song ⟨dugsong@monkey.org⟩
159BSD October 17, 2001 BSD