EoCE hints

• Take note of the stated assumptions.
• How might you utilize those in coming up with a solution?

• Trouble using dd(1)? Try this dd tutorial I wrote.
• Remember that parts are pieces of a whole
• Don't read from AND write to the same file at the same time.

• Problems with seq(1)?

lab46:~$ seq 1 10
1
2
3
4
5
6
7
8
9
10

• How about by an offset?

lab46:~$ seq 1 2 10
1
3
5
7
9

• How about backwards?

lab46:~$ seq 5 -1 0
5
4
3
2
1
0

• How to use in a loop?

for value in `seq 1 2 10`; do

• Or based on variables?

for value in `seq ${start} ${step} ${stop}`; do

• What, you mean I could have totally done that back then and saved myself all the hassle I went through?

lab46:~$ # yes

• Also, some usage examples:

lab46:~$ ./pwn1.sh 12 17 idbase with3 with7
   base 2 |   base 3 |   base 7 |   base 8 |   base10 |   base16 |
----------+----------+----------+----------+----------+----------+
 00001100 |    110-3 |    15(7) |      014 |   12(10) |     0x0C |
 00001101 |    111-3 |    16(7) |      015 |   13(10) |     0x0D |
 00001110 |    112-3 |    20(7) |      016 |   14(10) |     0x0E |
 00001111 |    120-3 |    21(7) |      017 |   15(10) |     0x0F |
 00010000 |    121-3 |    22(7) |      020 |   16(10) |     0x10 |
 00010001 |    122-3 |    23(7) |      021 |   17(10) |     0x11 |

lab46:~$ ./pwn1.sh 12 17 idbase with3 with7 noheader
 00001100 |    110-3 |    15(7) |      014 |   12(10) |     0x0C |
 00001101 |    111-3 |    16(7) |      015 |   13(10) |     0x0D |
 00001110 |    112-3 |    20(7) |      016 |   14(10) |     0x0E |
 00001111 |    120-3 |    21(7) |      017 |   15(10) |     0x0F |
 00010000 |    121-3 |    22(7) |      020 |   16(10) |     0x10 |
 00010001 |    122-3 |    23(7) |      021 |   17(10) |     0x11 |

lab46:~$ ./pwn1.sh 12 17 with3 with7 noheader
     1100 |      110 |       15 |       14 |       12 |        C |
     1101 |      111 |       16 |       15 |       13 |        D |
     1110 |      112 |       20 |       16 |       14 |        E |
     1111 |      120 |       21 |       17 |       15 |        F |
    10000 |      121 |       22 |       20 |       16 |       10 |
    10001 |      122 |       23 |       21 |       17 |       11 |

Also, it won't be the end of the world if you don't implement signed. I'm making that particular thing optional.

• authorized_keys might be something worth exploring
• your home directory follows you to the pi's, just as it does to the pods
• permissions on related files and directories are VERY important

• look inside readable text files. Useful information can be had that way.

• Some usage examples:

lab46:~$ ./catweek.sh
14
lab46:~$ ./catweek.sh fullname
week14
lab46:~$ ./catweek.sh fullname lastweek
week13
lab46:~$ ./catweek.sh nextweek
15
lab46:~$ ./catweek.sh start=monday
13
lab46:~$ ./catweek.sh start=monday nextweek fullname
week14
lab46:~$ ./catweek.sh 20180402 fullname
break2
lab46:~$ ./catweek.sh 20180402 fullname nobreaks
week11

Times so far (in seconds):

• 6653 seconds
• 6974 seconds
• 7029 seconds
• 8099 seconds
• 8550 seconds
• 9029 seconds
• 9157 seconds
• 10660 seconds
• 12506 seconds
• 13205 seconds
• 13512 seconds
• 15744 seconds

• Average time is 2.803 hours.

Be sure to plan accordingly.