cdenley
October 6th, 2008, 02:04 PM
Put this script in, for example, /usr/bin/setpass.py
#!/usr/bin/env python
import md5,sys,os,string,random
# Based on FreeBSD src/lib/libcrypt/crypt.c 1.2
# http://www.freebsd.org/cgi/cvsweb.cgi/~checkout~/src/lib/libcrypt/crypt.c?rev=1.2&content-type=text/plain
# Original license:
# * "THE BEER-WARE LICENSE" (Revision 42):
# * <phk@login.dknet.dk> wrote this file. As long as you retain this notice you
# * can do whatever you want with this stuff. If we meet some day, and you think
# * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
# This port adds no further stipulations. I forfeit any copyright interest.
def md5crypt(password, salt, magic='$1$'):
# /* The password first, since that is what is most unknown */ /* Then our magic string */ /* Then the raw salt */
m = md5.new()
m.update(password + magic + salt)
# /* Then just as many characters of the MD5(pw,salt,pw) */
mixin = md5.md5(password + salt + password).digest()
for i in range(0, len(password)):
m.update(mixin[i % 16])
# /* Then something really weird... */
# Also really broken, as far as I can tell. -m
i = len(password)
while i:
if i & 1:
m.update('\x00')
else:
m.update(password[0])
i >>= 1
final = m.digest()
# /* and now, just to make sure things don't run too fast */
for i in range(1000):
m2 = md5.md5()
if i & 1:
m2.update(password)
else:
m2.update(final)
if i % 3:
m2.update(salt)
if i % 7:
m2.update(password)
if i & 1:
m2.update(final)
else:
m2.update(password)
final = m2.digest()
# This is the bit that uses to64() in the original code.
itoa64 = './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmn opqrstuvwxyz'
rearranged = ''
for a, b, c in ((0, 6, 12), (1, 7, 13), (2, 8, 14), (3, 9, 15), (4, 10, 5)):
v = ord(final[a]) << 16 | ord(final[b]) << 8 | ord(final[c])
for i in range(4):
rearranged += itoa64[v & 0x3f]; v >>= 6
v = ord(final[11])
for i in range(2):
rearranged += itoa64[v & 0x3f]; v >>= 6
return magic + salt + '$' + rearranged
def getsalt(length):
chars = string.letters + string.digits
ret=""
for i in range(length):
ret+=random.choice(chars)
return ret
if len(sys.argv)<3:
print "You need to give a username and password"
print "usage: setpass.py user password"
sys.exit(2)
user=sys.argv[1]
passplain=sys.argv[2]
passcrypt=md5crypt(passplain, getsalt(8))
os.system("usermod -p "+passcrypt.replace("$","\\$")+" "+user)
set the permissions
sudo chown root:root /usr/bin/setpass.py
sudo chmod 700 /usr/bin/setpass.py
Now, whenever you want to change someone's password, run
sudo setpass.py user pass
Be aware, however, that the utilities included in linux don't allow you to give plaintext passwords as arguments for a very good reason. This would not be the safest approach to changing passwords.