Manual Pages  — NETDUMP

netdump client messages consist of a fixed-size header followed by a variable-sized payload. The header contains the message type, a sequence number, the offset of the payload data in the kernel dump, and the length of the payload data (not including the header). The message types are HERALD, FINISHED, KDH, VMCORE, and EKCD_KEY. netdump server messages have a fixed size and contain only the sequence number of the client message. These messages indicate that the server has successfully processed the client message with the corresponding sequence number. All client messages are acknowledged this way. Server messages are always sent to port 20024 of the client.

To initiate a netdump, the client sends a HERALD message to the server at port 20023. The client may include a relative path in its payload, in which case the netdump server should attempt to save the dump at that path relative to its configured dump directory. The server will acknowledge the HERALD using a random source port, and the client must send all subsequent messages to that port.

The KDH, VMCORE, and EKCD_KEY message payloads contain the kernel dump header, dump contents, and dump encryption key respectively. The offset in the message header should be treated as a seek offset in the corresponding file. There are no ordering requirements for these messages.

A netdump is completed by sending the FINISHED message to the server.

The following network drivers support netdump: alc(4), bge(4), bnxt(4), bxe(4), cxgb(4), em(4), igb(4), ix(4), ixl(4), mlx4en(4), mlx5en(4), re(4), vtnet(4).