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User talk:Haoqili

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Revision as of 15:14, 30 June 2009 by Haoqili (talk | contribs) (Kerberos Bugs I've encountered and fixed (started loggin since Jun 24th).)

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Kerberos Bugs I've encountered and fixed (started loggin since Jun 24th).

  • When trying to kinit username
ERROR: kinit: Cannot contact any KDC for realm [your realm fqdn] while getting initial credentials
SOLUTION: make sure KDC is running. /usr/local/sbin/krb5kdc
SOLUTION: 1. check log file. I looked in /var/log/auth.log. The bottom of it says: Cannot create reply cache file /var/tmp/krb5kdc_rcache: File exits. 2. sudo rm /var/tmp/krb5kdc_rcache.
  • Can't start krb5kdc and in auth.log it says:
ERROR: Address already in use - Cannot bind server socket to port [#] address [IP address]
SOLUTION: 1. see if it is true that port [#] is in use by netstat -nap | grep [#] (I also did pgrep -x krb5kdc). 2. kill the process: pkill -x krb5kdc. note the "-x" is for matching exactly the process "krb5kdc".
  • Can't start kadmind (know because echo $? = 1). The last chunk of auth.log says:
ERROR:
kadmind[6924]: No dictionary file specified, continuing without one.
kadmind[6924]: setting up network...
kadmind[6924]: Permission denied - Cannot bind server socket to port 464 address 0.0.0.0
kadmind[6924]: setsockopt(6,IPV6_V6ONLY,1) worked
kadmind[6924]: Permission denied - Cannot bind server socket to port 464 address ::
kadmind[6924]: skipping unrecognized local address family 17
kadmind[6924]: skipping unrecognized local address family 17
kadmind[6924]: Permission denied - Cannot bind server socket to port 464 address 192.168.165.145
kadmind[6924]: setsockopt(6,IPV6_V6ONLY,1) worked
kadmind[6924]: Permission denied - Cannot bind TCP server socket on ::.464
kadmind[6924]: Permission denied - Cannot bind RPC server socket on 0.0.0.0.749
kadmind[6924]: set up 0 sockets
kadmind[6924]: no sockets set up?
Reason (provided by tlyu): It is trying to bind to a privileged port. you need to give it a different port number. actually, two different port numbers: one for password changing and one for normal kadmin.
Solution:
in kdc.conf inserted the last two lines here
kdc_ports = 8888
kpasswd_port = 8887
kadmind_port = 8886

Python Bugs I've encountered and fixed

  • When talking to the terminal shell, a command (in my case, kdbt_util add_mkey) asks for password twice (second time is confirmation). I first tried:
p = Popen(command.split(), stdin=PIPE, stdout=PIPE, stderr=PIPE)
(out, err) = p.communicate('password')
(out2, err2) = p.communicate('password')
When I ran it, I got a chunk of error that ends with: ValueError: I/O operation on closed file. So what happens is that communicate closes the pipe, it breaks (even if it only runs once).
Solution code:
p = Popen(command.split(), stdin=PIPE, stdout=PIPE, stderr=PIPE)
p.stdin.write('password'+'\n')
p.stdin.write('password'+'\n')
Note don't forget the new line at the end.

Tips. Useful little things to know

Python

  • p = Popen('blah', stdin=PIPE, stdout=PIPE, stderr=PIPE)
(out, err) = p.communicate('inputThing\n') <-- don't forget the return "\n" at the end!
  • When you're doing a bunch of p=Popen('shell command') be careful because Popen starts a new branch so the next Popen might start without the previous one having completed. To fix this problem, put in:
if int(p.wait()) != 0: #meaning that it's not executed
print "error message"
exit
  • Two ways to display outputs after Popen( a command that has to get into something, in my case, getting into kadmin.local) 06262009
Way 1:
p = Popen(['commannd', 'all', 'in', 'one', 'line'], stdin=PIPE, stdout=PIPE, stderr=PIPE) #e.g. ['kadmin.local', '-q', 'listprincs']
if int(p.wait()) != 0:
print p.stdout.readlines()
Way 2:
p = Popen(['command', 'front', 'chunk'], stdin=PIPE, stdout=PIPE, stderr=PIPE) #e.g. ['kadmin.local']
(out, err) = p.communicate('rest of command') #e.g. 'listprincs'
print out