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IPKDB(4) NetBSD Kernel Interfaces Manual IPKDB(4)
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Maintained for NetBSD
by Kimmo Suominen.
Based on man-cgi by Panagiotis Christias.
ipkdb -- IP-based kernel debugger
options IPKDBKEY="\"IPKDB key for remote debugging\""
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 hard-
ware, 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
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 debugging
where debuggee 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 config-
ured 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 run-
ning, 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.
gdb(1), ddb(4), ip(4), udp(4), init(8)
ipkdb appeared in NetBSD 1.3 for the first time. Its configuration and
setup changed quite a bit in NetBSD 1.5.
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).
NetBSD 7.1.2 March 27, 2000 NetBSD 7.1.2