zeek/scripts/policy/protocols/dhcp/software.bro
Seth Hall e76b56ce53 Rework to the DHCP analyzer.
Highlights:
 - Reduced all DHCP events into a single dhcp_message event. (removed legacy events since they weren't widely used anyway)
 - Support many more DHCP options.
 - DHCP log is completely reworked and now represents DHCP sessions
   based on the transaction ID (and works on clusters).
 - Removed the known-devices-and-hostnames script since it's generally
   less relevant now with the updated log.
2018-03-01 08:36:32 -08:00

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##! Software identification and extraction for DHCP traffic.
@load base/protocols/dhcp
@load base/frameworks/software
module DHCP;
export {
redef enum Software::Type += {
## Identifier for web servers in the software framework.
DHCP::SERVER,
## Identifier for web browsers in the software framework.
DHCP::CLIENT,
};
redef record DHCP::Info += {
## Software reported by the client in the `vendor_class` option.
client_software: string &log &optional;
## Software reported by the server in the `vendor_class` option.
server_software: string &log &optional;
};
}
event DHCP::aggregate_msgs(ts: time, id: conn_id, uid: string, is_orig: bool, msg: DHCP::Msg, options: DHCP::Options) &priority=5
{
if ( options?$vendor_class )
{
if ( is_orig )
log_info$client_software = options$vendor_class;
else
{
log_info$server_software = options$vendor_class;
Software::found(id, [$unparsed_version=options$vendor_class,
$host=id$resp_h,
$software_type=DHCP::SERVER]);
}
}
}
event DHCP::log_dhcp(rec: DHCP::Info)
{
if ( rec?$assigned_addr && rec?$server_addr &&
(rec?$client_software || rec?$server_software) )
{
# Not quite right to just blindly use 67 and 68 as the ports
local id: conn_id = [$orig_h=rec$assigned_addr, $orig_p=68/udp,
$resp_h=rec$server_addr, $resp_p=67/udp];
if ( rec?$client_software && rec$assigned_addr != 255.255.255.255 )
{
Software::found(id, [$unparsed_version=rec$client_software,
$host=rec$assigned_addr,
$software_type=DHCP::CLIENT]);
}
if ( rec?$server_software )
{
Software::found(id, [$unparsed_version=rec$server_software,
$host=rec$server_addr,
$software_type=DHCP::SERVER]);
}
}
}