One more thing: 2013

Thursday, December 26, 2013

mout exfat in ubuntu

How to mount exfat in kali or ubuntu/debian like distribution, one solution occurred in many posts is like below,

apt-get install python-software-properties
add-apt-repository ppa:relan/exfat
apt-get update
apt-get install fuse-exfat
mount -t exfat /dev/sdc1 /media/exfat

but it doesn't work for me.

The other solution listed below works for me ,

apt-get install libfuse-dev # for fuse.h
download fuse-exfat from http://code.google.com/p/exfat/
follow instructions in http://code.google.com/p/exfat/wiki/HOWTO
scons
scons install
mount.exfat-fuse /dev/sdXn /mnt/exfat

Wednesday, December 25, 2013

my new kali source.list

My Kali repository mirror is referred to http://mirror.hust.edu.cn, but somehow, it is slow for me to do apt-get update and dist-upgrade. So I wanna to manually change the mirror site. According to instructions in http://www.blackmoreops.com/2013/11/14/change-repositories-different-mirror/, I currently change my mirror to http://mirrors.neusoft.edu.cn/ instead.

So my source.list is listed below,

for kali 1
#

# deb cdrom:[Debian GNU/Linux 7.0 _Kali_ - Official Snapshot i386 LIVE/INSTALL Binary 20130905-08:50]/ kali contrib main non-free
#deb cdrom:[Debian GNU/Linux 7.0 _Kali_ - Official Snapshot i386 LIVE/INSTALL Binary 20130905-08:50]/ kali contrib main non-free

#deb http://http.kali.org/kali kali main non-free contrib
#deb-src http://http.kali.org/kali kali main non-free contrib
#deb http://mirrors.neusoft.edu.cn/kali kali main non-free contrib
#deb-src http://mirrors.neusoft.edu.cn//kali kali main non-free contrib
#deb http://archive-4.kali.org/kali kali main non-free contrib
#deb-src http://archive-4.kali.org/kali kali main non-free contrib
deb http://kali.cs.nctu.edu.tw/kali kali main non-free contrib
deb-src http://kali.cs.nctu.edu.tw/kali kali main non-free contrib

## Security updates
#deb http://security.kali.org/kali-security kali/updates main contrib non-free
#deb http://mirrors.neusoft.edu.cn/kali-security kali/updates main contrib non-free
deb http://kali.cs.nctu.edu.tw/kali-security kali/updates main contrib non-free
#deb http://ftp.halifax.rwth-aachen.de/kali-security kali/updates main contrib non-free
#deb http://archive-4.kali.org/kali-securinty kali/updates main contrib non-free

for kali2
# Regular repositories
deb http://http.kali.org/kali sana main non-free contrib
deb http://security.kali.org/kali-security sana/updates main contrib non-free
# Source repositories
deb-src http://http.kali.org/kali sana main non-free contrib
deb-src http://security.kali.org/kali-security sana/updates main contrib non-free

Reference
http://www.blackmoreops.com/2015/08/13/how-to-add-official-kali-linux-repositories/

Thursday, December 05, 2013

zeroconf

In ubuntu or debian like distribution,
apt-get install avahi-daemon avahi-discover libnss-mdns

Try avahi-discover to discover nearby zeroconf machine.

Then check /etc/hostname content, for example mine is kali-j2c

Others can ping kali-j2c.local to reach this device.

Troubleshooting 1:
If the error "avahi-daemon disabled because there is a unicast .local domain" occurred, try to update /etc/default/avahi-daemon to make sure

Solution:
AVAHI_DAEMON_DETECT_LOCAL=0

Troubleshooting 2:
$update-rc.d avahi-daemon defaults
update-rc.d: using dependency based boot sequencing
insserv: warning: current start runlevel(s) (empty) of script `avahi-daemon' overrides LSB defaults (2 3 4 5).
insserv: warning: current stop runlevel(s) (0 1 2 3 4 5 6) of script `avahi-daemon' overrides LSB defaults (0 1 6).

Solution:
$update-rc.d avahi-daemon remove
$update-rc.d avahi-daemon defaults

Reference:
https://help.ubuntu.com/community/HowToZeroconf
http://www.jackenhack.com/raspberry-pi-avahi-daemon-disabled-because-there-is-a-unicast-local-domain-solved/
http://www.blackmoreops.com/2014/06/19/kali-linux-remote-ssh/

Thursday, May 30, 2013

libxml2 - process node in the tree.

Because the original code example which libxml2 demo tree1.c how to traverse the tree was using Recursive to process the relationship between the children node and the next node, but I think it is dangerous because we don't know when the stack overflow problem happen and it will happen sometime in the future.

the original code example


static void print_element_names(xmlNode * a_node)

{
xmlNode *cur_node = NULL;

for (cur_node = a_node; cur_node; cur_node = cur_node->next) {
if (cur_node->type == XML_ELEMENT_NODE) {
printf("node type: Element, name: %s\n", cur_node->name);
}
print_element_names(cur_node->children);
}

So I checked the xmlNode structure and find out the parent node is the useful hint to traverse the xml node tree.

Process the current node first.
Check the node if there is any children node and yes, process the children node.
Check the node if there is any next node and yes, process the next node.
If there is no children and next node,

check if there is any parent node and yes, go back to the parent node
When in the parent node, because it should be processed in step 0, check if there is any next node.
If there is a next node, repeat step 3.
If there is no any next node, repeat step 4.

Finally there is no next and parent node, the node should be the XML_DOCUMENT_NODE.

void do_indent(int indent)
{
for (; indent; --indent) {
putchar(' ');
putchar(' ');
}
}

int getNextNode( xmlNode **pCurr, int *deepth )
{
xmlNode *curr = *pCurr;

if ( curr->children!=NULL ) {
/* Move to the children node.
*/
curr = curr->children;
*deepth += 1;
} else if ( curr->next==NULL && curr->parent) {
/* Go back to the parent node.
then go to the next node of the parent node or
go to the parent node of the parent node if there is no any next node behind.
if there is no any parent node, it should be the XML_DOCUMENT_NODE.
*/
curr = curr->parent;
*deepth -= 1;
while ( curr->next==NULL && curr->parent!=NULL ) {
curr = curr->parent;
*deepth -= 1;
}
if ( curr->next!=NULL ) {
curr = curr->next;
} else {
/* It should be XML_DOCUMENT_NODE.
*/
curr = NULL;
}
} else {
curr = curr->next;
}

*pCurr = curr;

}

void process_node(xmlNode *pNode)
{
xmlNode *curr=NULL;

int indent=0;

if ( !pNode ) {
printf("No Node exist\n");
return;
}

for ( curr=pNode ; curr ; getNextNode(&curr, &indent)) {

if (curr->type == XML_ELEMENT_NODE) {
do_indent(indent);
printf("node type: Element, name: %s", curr->name);

if ( curr->properties ) {
process_attr(curr->properties);
}

printf("\n");
} else if ( curr->type==XML_TEXT_NODE ) {
do_indent(indent);
printf("node type: Text, name: %s\n", curr->content);
}
}
}

Tuesday, May 28, 2013

perl - lwp implement

#!/usr/bin/env perl

use strict;
use LWP;
use File::Basename;
use warnings;
use constant false => 0;
use constant true => 1;

my $host = "192.168.1.1";
my $prot = "https://";
my ($user, $pwd) = ("admin", "1234");
my @pathes = qw(/status_quickview.cgi);
my $ua = LWP::UserAgent->new();

$ua->cookie_jar({ file => "$ENV{HOME}/.cookies.txt", autosave=>1 });
push @{ $ua->requests_redirectable}, 'POST';
$ua->show_progress(true);

if ( is_login()==false ) { do_login(); }
foreach my $p (@pathes) {
do_get($p);
}
do_logout();

sub do_post {
my ($path, $query) = @_;
print "do_post($path)\n";
my $url = $prot . $host . $path;
my $req = HTTP::Request->new(POST => $url);
$req->content_type('application/x-www-form-urlencoded');
$req->content($query);
# print $req->as_string(),"\n";
my $resp = $ua->request($req);
if ( $resp->is_error() ) {
print $resp->status_line(), "\n";
exit();
}
# print $resp->content, "\n"; return $resp;
}

sub do_get {
my ($fullpath) = @_;
my ($name, $path, $suffix) = fileparse($fullpath);
print "do_get($fullpath)\n";
my $url = $prot . $host . $fullpath;
my $req = HTTP::Request->new(GET => $url);
# my $resp = $ua->request($req, $name);
my $resp = $ua->request($req);
if ( $resp->is_error() ) {
print $resp->status_line(), "\n";
exit();
}
# print $resp->content(), "\n";
return $resp;
}

sub do_login {
print "do_login()\n";
my $path = "/login_handler.cgi";
my $query = sprintf("username=%s&password=%s&Signin=Login", $user, $pwd);
my $resp = do_post($path, $query);
if ( 1 and $resp->content=~m/type=(\w+)/ ) {
# print "type=$1\n";
$ua->cookie_jar->set_cookie(0, 'type', $1, '/', $host);
$ua->cookie_jar->save();
}
}

sub is_login {
print "is_login()\n";
my $path = "/status_quickview.cgi";
my $resp = do_get($path);
if ( index($resp->content, "login.cgi")!=-1 ) {
return false;
} else {
return true;
}
}

sub do_logout {
print "do_logout()\n";
my $path = "/tools_logout.cgi";
my $resp = do_post($path, "apply=");
# print $resp->content, "\n";
}

C - Key/Value Pair Programming


/*

conf.txt
a=1
b=2
c=3
x=4
y=5
z=6

 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct {
  char *a;
  int  b;
  char *c;
  int  x;
  char *y;
  int  z;
} conf;

struct config_t {
  char *key;
  enum {
    TYPE_STR,
    TYPE_INT,
  } value_type;
  union {
    char **str_var;
    int *int_var;
  };
}
config_table[] = {
  {"a",  TYPE_STR,  {.str_var=&conf.a} },
  {"b",  TYPE_INT,  {.int_var=&conf.b}},
  {"c",  TYPE_STR,  {.str_var=&conf.c}},
  {"x",  TYPE_INT,  {.int_var=&conf.x}},
  {"y",  TYPE_STR,  {.str_var=&conf.y}},
  {"z",  TYPE_INT,  {.int_var=&conf.z}},
  {NULL, TYPE_STR, {NULL} }
};

int main(int argc, char *argv[])
{
  char buf[80];
  FILE *fp;
  struct config_t *pConfig;
  char *k, *v, *found;

  fp=fopen("conf.txt", "r");
  if ( !fp ) {
    perror("fopen failed");
    exit(1);
  }

  while ( fgets(buf, sizeof(buf), fp)!=NULL ) {
    found=strchr(buf, '\n');
    if ( found ) {
      *found=0x00;
    }

    found = strchr(buf, '=');
    if ( !found ) {
      continue;
    }
    *found=0x00;
    k=buf;
    v=found+1;

    pConfig = config_table;
    for (; pConfig->key ; ++pConfig) {
      if ( strcmp(k, pConfig->key)==0 ) {
        if ( pConfig->value_type==TYPE_STR ) {
          *pConfig->str_var = strdup(v);
        } else if ( pConfig->value_type==TYPE_INT ) {
          *pConfig->int_var = atoi(v);
        }
      }
    }
  }

  printf("a:%s\nb:%d\nc:%s\n", conf.a, conf.b, conf.c);
  printf("x:%d\ny:%s\nz:%d\n", conf.x, conf.y, conf.z);

  return 0;
}

Sunday, May 26, 2013

Perl experience - misc

In Perl, when to call subroutine with ampersand or parentheses. It's always confusing to me. Finally, I have some conclusion on it.

1. if perl can see the subroutine definition before invocation, ampersand can be omitted.
2. if perl can tell from the syntax that it's a subroutine call, for example sub(), ampersand can be omitted.
3. Otherwise, use &. Or you will get compilation error when using strict.

Correct Example
#!/usr/bin/env perl
use strict;
use warnings;

&sub1;

#
# the parentheses tell it's subroutine.
#
sub1();

sub sub1
{
  print "sub1\n";
}

#
# the subroutine defintion before invocation.
#
sub1;

Incorrect Example
#!/usr/bin/env perl
use strict;
use warnings;
sub1;

sub sub1
{
  print "sub1\n";
}

The Perl will complain

Bareword "sub1" not allowed while "strict subs" in use at sub.pl

Simple circular buffer implement

circular implement

#include
#include

#define BUF_SIZE 4

typedef struct {
enum {
BUFF_STATUS_EMPTY=0,
BUFF_STATUS_NOTEMPTY,
BUFF_STATUS_FULL
} status;
int b[BUF_SIZE];
int i;
int o;
} buff_t ;

void in(buff_t *buf)
{
int newp;
do {
newp= (buf->i+1)%BUF_SIZE;
if ( newp == buf->o ) {
buf->status=BUFF_STATUS_FULL;
break;
} else {
buf->status=BUFF_STATUS_NOTEMPTY;
buf->i=newp;
buf->b[buf->i]=buf->i;
}
} while (1) ;
}

void out(buff_t *buf)
{
int newp;
do {
newp=(buf->o+1)%BUF_SIZE;
if ( newp==buf->i ) {
buf->status = BUFF_STATUS_EMPTY;
break;
} else {
buf->o=newp;
printf("%d:%d\n", buf->o, buf->b[buf->o]);
buf->b[newp]=0x00;
}
} while (1);
}

int main(int argc, char *argv)
{
buff_t b1;
memset(&b1, 0x00, sizeof(b1));
for (;1;) {
if ( b1.status != BUFF_STATUS_FULL)
in(&b1);
if (b1.status != BUFF_STATUS_EMPTY)
out(&b1);
}
}

Stuff interested

List the stuff which I am interested.

Blackberry
C
C++
C#

Network Programming for the Microsoft® .NET Framework

Erlang
Java
Lua
Object C
Perl

Python

Foundations of Python Network Programming
python - aes implement

Ruby
Ubuntu

Wednesday, March 20, 2013

透過 http 存取 svn repository

記錄如何透過 http 存取 svn repository

以 bt5r3 為例

apache 設定檔位置在 /etc/apache2
mod_dav_svn.so

如果沒有 mod_dav_svn.so, 所以安裝 apt-get install libapache2-mod-python libapache2-svn, 安裝完後, 會產生 mod-avaiable/dav_svn.load, mod-available/dav_svn.conf, mod-enable/dav_svn.load, mod-enable/dav_svn.conf

編輯 mod-availble/dav_svn.conf

DAV svn

SVNParentPath /var/svn

AuthType Basic

AuthName "Subversion Repository"

AuthUserFile /etc/apache2/dav_svn.passwd

AuthzSVNAccessFile /etc/apache2/dav_svn.authz

Require valid-user

</Location>

編輯 dav_svn.passwd

htpasswd -cm /etc/apache2/dav_svn.passwd ${username}

編輯 dav_svn.authz

[groups]

[/]

${username} = rw

/etc/init.d/apache restart

Troubleshoot,

If "permission denies" occurred, try
chown -R www-data:www-data _the_svn_repository_directory_

Tuesday, February 19, 2013

boot from PXE

pxe client 選擇 pxe 開機, 透過 dhcp 取得本身 IP 與某個 file, 這個 file 也就是 pxe server 希望 pxe client 拿到 IP 之後, 再向 pxe server 透過 tftp 下載這個 file, 一般為 pxelinux.0
pxe client 拿到 pxelinux.0 之後, 會嘗試下載本身 ether mac address 相關的檔案, 直到 pxelinux.cfg/default
pxe server 可以透過 pxelinux.cfg/default, 提供開機選單訊息
此次實驗, pxe server 希望 pxe client 透過 nfs 掛載 bt5r3

Take bt5r3 as the pxe server
1. apt-get install dhcp3-server
/etc/dhcp3/dhcpd.conf
subnet 192.168.0.0 netmask 255.255.255.0 {
range 192.168.0.100 192.168.0.200;
filename "pxelinux.0";
}
設定本身 ip 為 192.168.0.100

/etc/init.d/dhcp3-sever restart

2. apt-get install tftpd-hpa
3. apt-get install nfs-kernel-server
/etc/export
/tftpboot *(rw,sync,no_subtree_check,no_root_squash,insecure)
/tftpboot/bt5r3 *(sync,insecure,no_root_squash,ro,no_subtree_check)

portmap
/etc/init.d/nfs-kernel-server restart
4. apt-get install syslinux
取得 pxelinux.0 執行檔

mount -t iso9660 -o loop bt5r3.iso /mnt
mkdir -p /tftpboot/bt5r3
cp -r /mnt/* /tftpboot/bt5r3

/tftpboot/pxelinux.0
cp /usr/lib/syslinux/pxelinux.0 /tftpboot/

/tftpboot/isolinux.msg
type bt5r3 to boot Backtrack 5 R3.

/tftpboot/pxelinux.cfg/default
TIMEOUT 100
DEFAULT bt5r3
PROMPT 1
DISPLAY /isolinux.msg
LABEL bt4
KERNEL bt5r3/casper/vmlinuz
APPEND initrd=bt5r3/casper/initrd.gz BOOT=casper boot=casper nopersistent rw quiet vga=0x317 netboot=nfs nfsroot=192.168.0.100:/tftpboot/bt5r3

參考資料

http://www.backtrack-linux.org/forums/showthread.php?t=1470
https://help.ubuntu.com/community/PXEInstallServer

One more thing