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 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 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

gdb(1), ddb(4), ip(4), udp(4), init(8)

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).