Building a libc offset database
Fetch all the configured libc versions and extract the symbol offsets. It will not download anything twice, so you can also use it to update your database:
$ ./get
You can also add a custom libc to your database.
$ ./add /usr/lib/libc-2.21.so
Find all the libc's in the database that have the given names at the given addresses. Only the last 12 bits are checked, because randomization usually works on page size level.
$ ./find printf 260 puts f30
archive-glibc (id libc6_2.19-10ubuntu2_i386)
Find a libc from the leaked return address into __libc_start_main.
$ ./find __libc_start_main_ret a83
ubuntu-trusty-i386-libc6 (id libc6_2.19-0ubuntu6.6_i386)
archive-eglibc (id libc6_2.19-0ubuntu6_i386)
ubuntu-utopic-i386-libc6 (id libc6_2.19-10ubuntu2.3_i386)
archive-glibc (id libc6_2.19-10ubuntu2_i386)
archive-glibc (id libc6_2.19-15ubuntu2_i386)
Dump some useful offsets, given a libc ID. You can also provide your own names to dump.
$ ./dump libc6_2.19-0ubuntu6.6_i386
offset___libc_start_main_ret = 0x19a83
offset_system = 0x00040190
offset_dup2 = 0x000db590
offset_recv = 0x000ed2d0
offset_str_bin_sh = 0x160a24
Check whether a library is already in the database.
$ ./identify /usr/lib/libc.so.6
id local-f706181f06104ef6c7008c066290ea47aa4a82c5