1.\"- 2.\" Copyright (c) 2018 Mark Johnston <markj@FreeBSD.org> 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd December 5, 2018 28.Dt NETDUMP 4 29.Os 30.Sh NAME 31.Nm netdump 32.Nd protocol for transmitting kernel dumps to a remote server 33.Sh SYNOPSIS 34To compile netdump client support into the kernel, place the following line in 35your kernel configuration file: 36.Bd -ragged -offset indent 37.Cd "options NETDUMP" 38.Ed 39.Sh DESCRIPTION 40netdump is a UDP-based protocol for transmitting kernel dumps to a remote host. 41A netdump client is a panicking kernel, and a netdump server is a host 42running the 43.Nm 44daemon, available in ports as 45.Pa ports/ftp/netdumpd . 46.Nm 47clients are configured using the 48.Xr dumpon 8 49utility. 50.Pp 51.Nm 52client messages consist of a fixed-size header followed by a variable-sized 53payload. 54The header contains the message type, a sequence number, the offset of 55the payload data in the kernel dump, and the length of the payload data 56(not including the header). 57The message types are 58.Dv HERALD , FINISHED , KDH , VMCORE , 59and 60.Dv EKCD_KEY . 61.Nm 62server messages have a fixed size and contain only the sequence number of 63the client message. 64These messages indicate that the server has successfully processed the 65client message with the corresponding sequence number. 66All client messages are acknowledged this way. 67Server messages are always sent to port 20024 of the client. 68.Pp 69To initiate a 70.Nm , 71the client sends a 72.Dv HERALD 73message to the server at port 20023. 74The client may include a relative path in its payload, in which case the 75.Nm 76server should attempt to save the dump at that path relative to its configured 77dump directory. 78The server will acknowledge the 79.Dv HERALD 80using a random source port, and the client must send all subsequent messages 81to that port. 82.Pp 83The 84.Dv KDH , VMCORE , 85and 86.Dv EKCD_KEY 87message payloads contain the kernel dump header, dump contents, and 88dump encryption key respectively. 89The offset in the message header should be treated as a seek offset 90in the corresponding file. 91There are no ordering requirements for these messages. 92.Pp 93A 94.Nm 95is completed by sending the 96.Dv FINISHED 97message to the server. 98.Pp 99The following network drivers support netdump: 100.Xr alc 4 , 101.Xr bge 4 , 102.Xr bnxt 4 , 103.Xr bxe 4 , 104.Xr cxgb 4 , 105.Xr em 4 , 106.Xr igb 4 , 107.Xr ix 4 , 108.Xr ixl 4 , 109.Xr mlx4en 4 , 110.Xr re 4 , 111.Xr vtnet 4 . 112.Sh SYSCTL VARIABLES 113The following variables are available as both 114.Xr sysctl 8 115variables and 116.Xr loader 8 117variables: 118.Bl -tag -width "indent" 119.It Va net.netdump.debug 120Control debug message verbosity. 121Debug messages are disabled by default, but are useful when troubleshooting 122or when developing driver support. 123.It Va net.netdump.path 124Specify a path relative to the server's dump directory in which to store 125the dump. 126For example, if the 127.Nm 128server is configured to store dumps in 129.Pa /var/crash , 130a path of 131.Dq foo 132will cause the server to attempt to store dumps from the client in 133.Pa /var/crash/foo . 134The server will not automatically create the relative directory. 135.It Va net.netdump.polls 136The client will poll the configured network interface while waiting for 137acknowledgements. 138This parameter controls the maximum number of poll attempts before giving 139up, which typically results in a re-transmit. 140Each poll attempt takes 0.5ms. 141.It Va net.netdump.retries 142The number of times the client will re-transmit a packet before aborting 143a dump due to a lack of acknowledgement. 144The default may be too small in environments with lots of packet loss. 145.It Va net.netdump.arp_retries 146The number of times the client will attempt to learn the MAC address of 147the configured gateway or server before giving up and aborting the dump. 148.El 149.Sh SEE ALSO 150.Xr decryptcore 8 , 151.Xr dumpon 8 , 152.Xr savecore 8 153.Sh HISTORY 154.Nm 155client support first appeared in 156.Fx 12.0 . 157.Sh BUGS 158Only IPv4 is supported. 159.Pp 160.Nm 161may only be used after the kernel has panicked. 162