Date: Thu, 03 Oct 2002 22:44:06 +0100 From: Mark Murray <mark@grondar.za> To: "Firsto Lasto" <firstolasto@hotmail.com> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: PRNG not seeded - error in non-root ssh inside 4.6.2 jails... Message-ID: <200210032144.g93Li620007510@grimreaper.grondar.org> In-Reply-To: <F2001Y7PeGbPn6U9Bek000012cd@hotmail.com> ; from "Firsto Lasto" <firstolasto@hotmail.com> "Thu, 03 Oct 2002 14:14:31 PDT." References: <F2001Y7PeGbPn6U9Bek000012cd@hotmail.com>
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> I can't seed it by banging on the keyboard - it is a headless server in a > rack thousands of miles from me :) > > Perhaps there is another way to do it ? Yes. You need to find sources of entropy in interrupts. Look at a dmesg, and note which IRQ's your network device(s) and mass storage controller(s) (both SCSI and ATA). Use any other irq's that aren't too busy and may be somewhat random. Staring at a 'systat 2 -vmstat' screen (right hand side) may give some clues. Then use rndcontrol(8) to set up the seeding. There is a knob in rc.conf to make this setting survive the next reboot. M > >Date: Thu, 03 Oct 2002 21:54:30 +0100 > > > > > Sorry, here is the rest: > > > > > > Here is the output of the `dd` command using urandom: > > > > > > dd if=/dev/urandom of=/dev/stdout bs=512 count=1 | hexdump -C > > > 1+0 records in > > > 1+0 records out > > > 00000000 a0 69 1a 7c 8f 32 e5 21 ae 7a 33 14 68 0b 8e a6 > > > |.i.|.2.!.z3.h...| > > > >... etc. Looking good. > > > > > $ ls -l /dev/*rand* > > > crw-r--r-- 1 root wheel 2, 3 Sep 3 21:46 /dev/random > > > crw-r--r-- 1 root wheel 2, 4 Sep 3 21:46 /dev/urandom > > > >Also good. > > > > > > > So then, as root I ran: `chmod 0666 /dev/stdout` and then I ran your > > > >`dd` > > > > > command and got: > > > > > > > > > > $ dd if=/dev/random of=/dev/stdout bs=512 count=1 | hexdump -C > > > > > 0+0 records in > > > > > 0+0 records out > > > > > 0 bytes transferred in 0.000036 secs (0 bytes/sec) > > > >Can you try a few of these while furiously abusing your keyboard? > >I'm trying to see if /dev/random can be persuaded to give _any_ > >aoutput at all. > > > >Maybe do it on a vty instead of in X. > > > >M > >-- > >o Mark Murray > >\_ > >O.\_ Warning: this .sig is umop ap!sdn > > > > > _________________________________________________________________ > Chat with friends online, try MSN Messenger: http://messenger.msn.com > -- o Mark Murray \_ O.\_ Warning: this .sig is umop ap!sdn To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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