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this circuit does not work, but could be benefical to understand the roles of two branches which leads between capacitor and base of transistor.
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http://www.falstad.com/circuit/#%24+1+5 ... 25+0+-1%0A
astable multivibrator circuit acting as a led flasher. data for simulation java applet http://www.falstad.com/circuit/ . led is expected to be about 2.5v, 20 mA and power dc supply 9v battery. not tested in real!
$ 1 5.0E-6 5.934295036739208 50 2.0 50
v 384 64 336 64 0 0 40.0 5.0 0.0 0.0 0.5
t 288 208 320 208 0 1 -4.184713778629777 0.13619941217392795 100.0
t 128 208 96 208 0 1 0.6154526523446024 0.6523326150314848 100.0
c 176 208 144 208 0 1.0E-5 4.1739553582352125
c 240 208 272 208 0 1.0E-5 -0.6046942319500379
w 288 208 272 208 0
w 128 208 144 208 0
w 320 288 96 288 0
w 96 224 96 288 0
w 384 288 384 64 0
w 320 64 320 112 0
r 320 112 320 144 0 350.0
w 96 64 96 112 0
r 96 112 96 144 0 350.0
w 96 144 96 192 0
w 336 64 320 64 0
w 320 144 320 192 0
w 240 208 96 144 0
162 320 224 320 288 1 2.1024259 1.0 0.0 0.0
w 320 288 384 288 0
w 176 208 320 144 0
w 96 64 208 64 0
w 208 64 320 64 0
r 208 64 128 208 0 2000.0
r 208 64 288 208 0 2000.0
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Below is a export of basic astable multivibrator circuit for http://www.falstad.com/circuit/ . The resistor and capacitor values are just by eye so in real this circuit might have problems.
$ 1 5.0E-6 0.34903429574618416 50 2.0 50
v 384 64 336 64 0 0 40.0 5.0 0.0 0.0 0.5
t 288 208 320 208 0 1 0.6426223132462627 0.6640109176265421 100.0
t 128 208 96 208 0 1 -3.994528534287322 -0.14567302984614652 100.0
c 176 208 144 208 0 1.0E-5 0.1670616342264259
c 240 208 272 208 0 1.0E-5 3.1848445868146333
w 288 208 272 208 0
w 128 208 144 208 0
w 320 288 96 288 0
w 320 224 320 288 0
w 96 224 96 288 0
w 320 288 368 288 0
w 384 288 384 64 0
w 256 64 176 64 0
w 176 64 144 64 0
w 320 64 320 112 0
w 128 64 128 112 0
r 128 112 128 144 0 1000.0
r 320 112 320 144 0 350.0
w 96 64 96 112 0
r 96 112 96 144 0 350.0
w 96 144 96 192 0
w 336 64 320 64 0
w 304 64 320 64 0
w 320 144 320 192 0
w 368 288 384 288 0
w 128 208 128 144 0
w 272 208 272 144 0
r 272 112 272 144 0 1000.0
w 272 64 272 112 0
w 144 64 128 64 0
w 128 64 96 64 0
w 256 64 272 64 0
w 304 64 272 64 0
w 176 208 320 144 0
w 240 208 96 144 0
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http://www.falstad.com/circuit/
This java applet is an electronic circuit simulator. When the applet starts up you will see an animated schematic of a simple LRC circuit. The green color indicates positive voltage. The gray color indicates ground. A red color indicates negative voltage. The moving yellow dots indicate current.
http://www.ohmpie.com/hm555/
Home made 555 timer from NPN and PNP transistors
http://talkingelectronics.com/projects/ ... cuits.html
Save 50 - 555 Circuits (more than 97 Circuits) as: .doc (2.1MB) or .pdf (1.4MB) (26-5-2011)
http://www.electronics-tutorials.ws/wav ... table.html
Regenerative switching circuits such as Astable Multivibrators are the most commonly used type of relaxation oscillator as they produce a constant square wave output waveform as well as their simplicity, reliability and ease of construction.
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http://www.csgnetwork.com/resistcolcalc.html
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NFSv4 "supports" the following security mechanisms
NFSv4 using AUTH_SYS
NFSv4 using AUTH_GSS (Kerberos 5)
NFSv4 using AUTH_GSS (SPKM-3)*
NFSv4 using AUTH_GSS (LIPKEY)*
NFSv4 Name to ID mapping
http://www.citi.umich.edu/projects/nfsv4/linux/faq/
GSS_API - Generic Security Services Application Program Interface
http://en.wikipedia.org/wiki/Generic_Se ... _Interface
SPKM - Simple Public-Key GSS-API Mechanism (SPKM)
http://tools.ietf.org/html/rfc2025
*GSS-API mechanism which is based on a public-key, rather than a symmetric-key, infrastructure
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TGT renewal might be useful for long running job which mounts NFS/RKB share.
- max_life and max_renewable_life in /var/kerberos/krb5kdc/kdc.conf on the KDC servers as in shipped example /usr/kerberos/share/examples/krb5/kdc.conf (if you do use CentOS/RHEL)
[kdcdefaults]
kdc_ports = 750,88
[realms]
ATHENA.MIT.EDU = {
database_name = /usr/local/var/krb5kdc/principal
admin_keytab = FILE:/usr/local/var/krb5kdc/kadm5.keytab
acl_file = /usr/local/var/krb5kdc/kadm5.acl
key_stash_file = /usr/local/var/krb5kdc/.k5.ATHENA.MIT.EDU
kdc_ports = 750,88
max_life = 10h 0m 0s
max_renewable_life = 7d 0h 0m 0s
}
- ticket_lifetime in /etc/krb5.conf on the client machine
[libdefaults]
default_realm = REALM
dns_lookup_realm = false
dns_lookup_kdc = false
forwardable = yes
ticket_lifetime = 32d
renew_lifetime = 32d
- maxlife for the user and krbtgt/REALM principal
kadmin: modprinc -maxlife 32days -maxrenewlife 32days +allow_renewable krbtgt/REALM
kadmin: modprinc -maxlife 32days -maxrenewlife 32days +allow_renewable user/REALM
- output of the getprinc for user
kadmin: getprinc USER
Principal: USER@REALM
Maximum ticket life: 32 days 00:00:00
Maximum renewable life: 32 days 00:00:00
- maxlife for the service principal "krbtgt/REALM"
kadmin: getprinc krbtgt/domain.com@REALM
Maximum ticket life: 32 days 00:00:00
Maximum renewable life: 32 days 00:00:00
- request extended lifetime and renewal in the ticket request
$ kinit -l 14d -r 14d
- to renew the ticket, use the kinit -R option before the ticket expires
$ kinit -R
links:
http://linsec.ca/Using_Kerberos_5_for_S ... entication
k5start and krenew are modified versions of kinit which add support for running as a daemon to maintain a ticket cache, running a command with credentials from a keytab and maintaining a ticket cache until that command completes, obtaining AFS tokens (via an external aklog) after obtaining tickets, and creating an AFS PAG for a command. They are primarily useful in conjunction with long-running jobs; for moving ticket handling code out of servers, cron jobs, or daemons; and to obtain tickets and AFS tokens with a single command.
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Kerberos overview
To understand MIT Kerberos design and functionality I strongly recommend to read "Designing an Authentication System" dialogue, which, even though, was written some time ago, is still the best Kerberos overview material available. You may find it here: http://web.mit.edu/kerberos/www/dialogue.html
Simple RHEL/CentOS setup guide
A basic setup guide which, along with the "Dialogue", will help you to setup the basic functional Kerberos realm http://www.centos.org/docs/5/html/Deplo ... beros.html
NFS
While combining the Kerberos with NFSv4 you may find some tips here: https://help.ubuntu.com/community/NFSv4Howto
Schopenhauer Implementation
And some extract of the Schopenhauer's work may be assimilated here: http://feuerteufel.blog.cz/1001/svet-ja ... redstava-1
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