getting canaries https://medium.com/@cedriczirtacic/peque%C3%B1o-texto-canarios-en-el-stack-3ce23f6c033b

gdb.sh

(gdb) disas main
Dump of assembler code for function main:
   0x00000000004005ab <+0>:     sub    $0x18,%rsp
   0x00000000004005af <+4>:     mov    %fs:0x28,%rax
   0x00000000004005b8 <+13>:    mov    %rax,0x8(%rsp)
   0x00000000004005bd <+18>:    xor    %eax,%eax
   0x00000000004005bf <+20>:    callq  0x400566 <get_canary>
   0x00000000004005c4 <+25>:    mov    (%rax),%rsi
   0x00000000004005c7 <+28>:    mov    $0x400688,%edi
   0x00000000004005cc <+33>:    mov    $0x0,%eax
   0x00000000004005d1 <+38>:    callq  0x400460 <printf@plt>
   0x00000000004005d6 <+43>:    mov    0x8(%rsp),%rdx
   0x00000000004005db <+48>:    xor    %fs:0x28,%rdx
   0x00000000004005e4 <+57>:    jne    0x4005eb <main+64>
   0x00000000004005e6 <+59>:    add    $0x18,%rsp
   0x00000000004005ea <+63>:    retq
   0x00000000004005eb <+64>:    callq  0x400450 <__stack_chk_fail@plt>
End of assembler dump.
(gdb) b *main+13
Breakpoint 1 at 0x4005b8
(gdb) r
Starting program: /tmp/main

Breakpoint 1, 0x00000000004005b8 in main ()
(gdb) print/x $rax
$1 = 0x1ff274c196d54d00
(gdb) q