zeek/scripts/policy/protocols/dhcp/software.bro
Jon Siwek 81133f3116 Merge remote-tracking branch 'origin/topic/seth/dhcp-update'
* origin/topic/seth/dhcp-update:
  Rework to the DHCP analyzer.
  First step of DHCP analyzer rearchitecture.
  Add .btest scripts for dhck_ack and dhcp_discover messages verifying that new options are correctly reported in dhcp.log records.
  Extend DHCP protocol analyzer with new options.

BIT-1924 #merged

Additional changes:

* Removed known-hosts.bro as the only thing populating its table was
  the already-removed known-hosts-and-devices.bro.  So a
  known_devices.log will no longer be generated.

* In dhcp-options.pac, the process_relay_agent_inf_option had a memleak
  and also process_auto_proxy_config_option looked like it accessed one
  byte past the end of the available bytestring, so fixed those.
2018-05-01 18:06:41 -05:00

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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]);
}
}
}