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Add support for DHCP client identifier

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see https://datatracker.ietf.org/doc/html/rfc2132#section-9.14
Closes #2468
This commit is contained in:
nnposter
2022-06-08 22:59:30 +00:00
parent 4f6e7307e4
commit f0e85baf85
3 changed files with 74 additions and 4 deletions
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34
scripts/dhcp-discover.nse
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@@ -45,6 +45,13 @@ Some of the more useful fields:
-- request. Keep in mind that you may not see the response if
-- a non-native address is used. Setting it to <code>random</code> will
-- possibly cause the DHCP server to reserve a new IP address each time.
-- @args dhcp-discover.clientid Client identifier to use in DHCP option 61.
-- The value is a string, while hardware type 0, appropriate for FQDNs,
-- is assumed. Example: clientid=kurtz is equivalent to specifying
-- clientid-hex=00:6b:75:72:74:7a (see below).
-- @args dhcp-discover.clientid-hex Client identifier to use in DHCP option 61.
-- The value is a hexadecimal string, where the first octet is
-- the hardware type.
-- @args dhcp-discover.requests Set to an integer to make up to that many
-- requests (and display the results).
--
@@ -74,6 +81,10 @@ Some of the more useful fields:
-- </table>
--
--
-- 2022-04-22 - Revised by nnposter
-- o Implemented script arguments "clientid" and "clientid-hex" to allow
-- passing a specific client identifier (option 61)
--
-- 2020-01-14 - Revised by nnposter
-- o Added script argument "mac" to prescribe a specific MAC address
@@ -123,6 +134,7 @@ action = function(host, port)
return stdnse.format_output(false, "Couldn't determine local IP for interface: " .. host.interface)
end
local options = {}
local overrides = {}
local macaddr = (stdnse.get_script_args(SCRIPT_NAME .. ".mac") or "native"):lower()
@@ -152,11 +164,31 @@ action = function(host, port)
macaddr_iter = function () return macaddr end
end
local clientid = stdnse.get_script_args(SCRIPT_NAME .. ".clientid")
if clientid then
clientid = "\x00" .. clientid -- hardware type 0 presumed
else
clientid = stdnse.get_script_args(SCRIPT_NAME .. ".clientid-hex")
if clientid then
clientid = clientid:gsub(":", "")
if not clientid:find("^%x+$") then
return stdnse.format_output(false, "Invalid hexadecimal client ID")
end
clientid = stdnse.fromhex(clientid)
end
end
if clientid then
if #clientid == 0 or #clientid > 255 then
return stdnse.format_output(false, "Client ID must be between 1 and 255 characters long")
end
table.insert(options, {number = 61, type = "string", value = clientid })
end
local results = {}
for i = 1, reqcount do
local macaddr = macaddr_iter()
stdnse.debug1("Client MAC address: %s", stdnse.tohex(macaddr, {separator = ":"}))
local status, result = dhcp.make_request(host.ip, dhcptypeid, iface.address, macaddr, nil, nil, overrides)
local status, result = dhcp.make_request(host.ip, dhcptypeid, iface.address, macaddr, options, nil, overrides)
if not status then
return stdnse.format_output(false, "Couldn't send DHCP request: " .. result)
end