Hitchhiker's Guide to Openbsd

8.9 - OpenBSD Bootloader (i386, amd64 specific)
When booting your OpenBSD system, you have probably noticed the boot prompt. 
boot> 
For most people, you won't have to do anything here. It will automatically boot if no commands are 
given. But sometimes problems arise, or special functions are needed. That's where these options will 
come in handy. To start off, you should read through the 
boot(8)
 man page. Here we will go over the 
most common used commands for the bootloader. 
To start off, if no commands are issued, the bootloader will automatically try to boot /bsd. If that fails it 
will try /obsd, and if that fails, it will try /bsd.old. You can specify a kernel by hand by typing: 
http://www.openbsd.org/faq/faq8.html (7 of 20)9/4/2011 10:02:10 AM

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8 - General Questions
boot> boot hd0a:/bsd
or 
boot> b /bsd
This will boot the kernel named 
bsd
from the 'a' partition of the first BIOS recognized hard disk. 
Here is a brief list of options you can use with the OpenBSD kernel. 
●
-a : This will allow you to specify an alternate root device after booting the kernel. 
●
-c : This allows you to enter the boot time configuration. Check the 
Boot Time Config
section of 
the FAQ. 
●
-s : This is the option to boot into single user mode. 
●
-d : This option is used to dump the kernel into ddb. Keep in mind that you must have DDB built 
into the kernel. 
These are entered in the format of: boot [ image [-acds]] 
For further reading you can read 
boot(8)'s man page
. 
8.10 - S/Key
S/Key is a ``one-time password'' authentication system. It can be useful for people who don't have the 
ability to use an encrypted channel which protects their authentication credentials in transit, as can be 
established using 
ssh(1)
. 
WARNING: One-time password systems only protect authentication information. They do not prevent 
network eavesdroppers from gaining access to private information. Furthermore, if you are accessing a 
secure system A, it is recommended that you do this from another trusted system B, to ensure nobody is 
gaining access to system A by logging your keystrokes or by capturing and/or forging input and output 
on your terminal devices. 
The S/Key system generates a sequence of one-time (single use) passwords from a user's secret 
passphrase along with a challenge received from the server, by means of a secure hash function. The 
system is only secure if the secret passphrase is never transferred over the network. Therefore