NAME
ipkdb —
IP-based kernel debugger
SYNOPSIS
options IPKDB
options IPKDBSECURE
options IPKDBKEY="\"IPKDB key for remote
debugging\""
options IPKDB_NE_PCISLOT=x
DESCRIPTION
ipkdb is a kernel debugger that uses UDP and IP to
communicate with a remote debugger (normally
gdb(1)).
Since the debugger uses its own driver to talk to the networking
hardware, the number of supported network interfaces is a lot less than what
is supported by the kernel. At the time of this writing, there is only
support for a NE2000 compatible card in a PCI slot. In order for
ipkdb to find your card, you need to specify the
slot the card is in via the options
IPKDB_NE_PCISLOT.
To use ipkdb, you have to set up a DHCP
server, from which ipkdb can get the IP address for
the interface that is used for debugging.
To enter ipkdb, the remote debugger has to
send the protocol start packet. E.g., gdb will do this on the command
target ipkdb debuggee IPKDB key for
remote debuggingdebuggee is the name of the machine to debug
(which must resolve to the IP address of the interface), and the rest of the
line corresponds to the definition of IPKDBKEY (see
below). For ipkdb to actually see this packet, the
interface which is used for debugging has to be set up to actually receive
packets, i.e. it has to be up and running.
To prevent messing around with a secured system,
ipkdb normally also checks the security level at
which the kernel is running. ipkdb will only work
with security levels less than 1, unless the kernel is configured with
options IPKDBSECURE.
In addition, the debugger is forcedly entered on a panic, as well
as on initial startup, if you boot the kernel with the
-d option (note that this however is machine
dependent). On such a forced enter to ipkdb there is
no need for the interface in question to already be up and running, since
ipkdb only needs to send/receive packets via its own
driver.
As some form of security against the occasional hacker,
ipkdb uses the definition of
options IPKDBKEY to compute a checksum on the data
in every packet. The remote debugger has to send this checksum, based on the
data it sends and the key, or ipkdb ignores the
packet. This is also used in order to check against data errors on the
connection.
SEE ALSO
HISTORY
ipkdb appeared in NetBSD
1.3 for the first time. Its configuration and setup changed quite a
bit in NetBSD 1.5.
BUGS
Since the kernel includes the definition of IPKDBKEY, anyone who
can read the kernel can extract it and use it to enter
ipkdb.
There is no support for ip6(4).