Mechanics is the branch of physics concerned with the behaviour of physical bodies when subjected to forces or displacements, and the subsequent effect of the bodies on their environment.
Author Archives: jeffrin
FAI. Fully Automatic Installation.
FAI Installation Steps Network boot via PXE Run scripts to determine FAI classes and variables Partition local hard disks and create RAID, LVM configuration and the file systems Install and configure software packages Customize OS and software to your local needs Reboot freshly installed machine http://www.informatik.uni-koeln.de/fai/features/
tcp tuning tcp_syncookies
tcp_syncookies. Send out syncookies when the syn backlog queue of a socket overflows. This is to prevent against the common “syn flood attack”. Disabled (0) by default. :–:cat /proc/sys/net/ipv4/tcp_syncookies 0 :–: added from linux kernel source. /* 160 * Generate a syncookie. mssp points to the mss, which is returned 161 * rounded down to …
What does rfc 1337 say ?
From RFC 1337. TIME-WAIT state removes the hazard of old duplicates for “fast” or “long” connections, in which clock-driven ISN selection is unable to prevent overlap of the old and new sequence spaces. The TIME-WAIT delay allows all old duplicate segments time enough to die in the Internet before the connection is reopened. echo 1 …
tcp tuning tcp_rfc1337
From RFC 1337. TIME-WAIT state removes the hazard of old duplicates for “fast” or “long” connections, in which clock-driven ISN selection is unable to prevent overlap of the old and new sequence spaces. The TIME-WAIT delay allows all old duplicate segments time enough to die in the Internet before the connection is reopened. echo 1 …
generating random passwords.
makepass.py from random import choice import string def GenPasswd(length=8, chars=string.letters+string.digits): return ”.join([ choice(chars) for i in range(length) ]) ahiliation:~$python Python 2.5.5 (r255:77872, Mar 20 2010, 05:19:32) [GCC 4.4.3] on linux2 Type “help”, “copyright”, “credits” or “license” for more information. >>> import makepass >>> for i in range(6): … print makepass.GenPasswd(12) … BSxqLK9mpq4R FRlppP7K2Che YBkz0QZMJojC JjTQlcHzDsC3 …
fopen64 programming
fopen64(“/home/jeffrin/.netrc”, “r”) = 0 The fopen64() function is identical to the fopen() function except that the underlying file descriptor is created with the O_LARGEFILE flag set. The fopen64() function is a part of the large-file extensions. http://coding.derkeiler.com/Archive/C_CPP/comp.lang.c/2008-07/msg00256.html
getservbyname programming
The getservbyname() function returns a servent structure for the entry from the database that matches the service name using protocol proto. If proto is NULL, any protocol will be matched. A connection is opened to the database if necessary. getservbyname(“ftp”, “tcp”) = 0x7fcc5248b8c0 The servent structure is defined in as follows: struct servent { char …
wcwidth – determine columns needed for a wide character
UNIX API wcwidth – determine columns needed for a wide character API Explanation Code #define _XOPEN_SOURCE #include <wchar.h> #include<stdio.h> main() { int value; wchar_t cr; cr=’H’; value=wcwidth(cr); printf(“n %d n”,value); } http://gcc.gnu.org/ml/gcc-bugs/2000-10/msg00540.html
wcwidth programming
wcwidth – determine columns needed for a wide character #define _XOPEN_SOURCE #include <wchar.h> #include<stdio.h> main() { int value; wchar_t cr; cr=’H’; value=wcwidth(cr); printf(“\n %d \n”,value); } http://gcc.gnu.org/ml/gcc-bugs/2000-10/msg00540.html