Wednesday, 30 May 2012

Mysql 5.6 new features

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Sunday, 20 May 2012

Cisco Anyconnect Errors


Anyconnect client gives this error


AnyConnect cannot confirm it is connected to your secure gateway.  The local network may not be trustworthy.  Please try another network.

After fighting it for a while, I found an answer in the release notes

http://www.cisco.com/en/US/docs/security/vpn_client/anyconnect/anyconnect25/release/notes/anyconnect25rn.html

Firefox 2.0 or later with libnss3.so installed in /usr/local/lib, /usr/local/firefox/lib, or /usr/lib. Firefox must be installed in /usr/lib or /usr/local, or there must be a symbolic link in /usr/lib or /usr/local called firefox that points to the Firefox installation directory.



So the following fixes it


mkdir /usr/local/firefox

cd /usr/local/firefox

ln -s /usr/lib64/libnss3.so 

ln -s /lib64/libplc4.so 

ln -s /lib64/libnspr4.so 

ln -s /usr/lib64/libsmime3.so

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Wednesday, 18 January 2012

Linux file descriptors and open modes

Ever want to find out what modes a file was opened with originally ?

First find the file descriptor number
ls /proc//fd
Eg
ls -l /proc/32048/fd/30
l-wx------ 1 apache apache 64 Jan 18 07:15 30 -> /var/log/httpd/ntop-access_log


Then check fdinfo 

cat /proc/32048/fdinfo/30
pos: 0
flags: 0102001

The flags are derived from the open system call http://linux.about.com/od/commands/l/blcmdl2_open.htm

To actually decipher the octal codes , look under /usr/include/bits/fcntl.h

If there are multiple codes, the codes are appended together.
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Thursday, 12 January 2012

Linux ACLs

Filesystem options and commands


First check to make sure the file system is mounted with acl settings

cat /proc/mounts |grep acl


/dev/sda1 / ext3 rw,noatime,relatime,errors=remount-ro,acl,data=ordered 0 0

If not update /etc/fstab and add 'acl' to the options section and remount the file system

getfacl, setfacl, chacl are the two main commands. chacl is available for IRIX compatibility.


Use Cases


Grant 2 users permissions to the same directory and files under it


Let's say we want to grant user john and mary permissions to folder /var/www/mysite.com

We can start by creating the directory. At this point we can leave it owned by root as the ACLs will help here.

ls -ld /var/www/mysite.com/
drwxr-xr-x 2 root root 4096 Feb 11 15:21 /var/www/mysite.com/

The first 2 commands grant users john and mary permissions.

The second sets the default acl. This causes the acls to be applied with inhertiance set. So this makes good sense in a multi user multi edit environment. The next arguments between the : are the username and the permissions

setfacl -m john:rwx mysite.com 
setfacl -m mary:rwx mysite.com 

setfacl -m default:john:rwx mysite.com 
setfacl -m default:mary:rwx mysite.com


# file: mysite.com
# owner: root
# group: root
user::rwx
user:john:rwx
group::r-x
mask::rwx
other::r-x
default:user::rwx
default:user:john:rwx
default:user:mary:rwx
default:group::r-x
default:mask::rwx
default:other::r-x

Now create a file by logging in a user john.

john@slice01$ echo "john" > file1

john@slice01$ ls -l file1 
-rw-rw-r--+ 1 john john 4 Feb 11 15:31 file1

john@slice01$ getfacl file1 
# file: file1
# owner: john
# group: john
user::rw-
user:john:rwx   #effective:rw-
user:mary:rwx   #effective:rw-
group::r-x   #effective:r--
mask::rw-
other::r--

Then create a directory

john@slice01$ mkdir john

john@slice01$ getfacl john
# file: john
# owner: john
# group: john
user::rwx
user:john:rwx
user:mary:rwx
group::r-x
mask::rwx
other::r-x
default:user::rwx
default:user:john:rwx
default:user:mary:rwx
default:group::r-x
default:mask::rwx
default:other::r-x

As you can see mary is there in the ACLs also

You can test it by logging in as user mary & editing files created by john.

mary@slice01$ echo mary >> file1 

mary@slice01$ cat file1 
john
mary

mary@slice01$ cd john/

mary@slice01 $ echo mary > file2
mary@slice01 $ getfacl file2 
# file: file2
# owner: mary
# group: mary
user::rw-
user:john:rwx   #effective:rw-
user:mary:rwx   #effective:rw-
group::r-x   #effective:r--
mask::rw-
other::r--



Grant 2 users permissions to the same directory and files under it except to 2 individual directories

Lets say we want john and mary to have permissions under /var/www/mysite.com/ and all files but still have individual directories
/var/www/mysite.com/john & /var/www/mysite.com/mary

 getfacl mary
# file: mary
# owner: mary
# group: mary
user::rwx
user:john:rwx
user:mary:rwx
group::r-x
mask::rwx
other::r-x
default:user::rwx
default:user:john:rwx
default:user:mary:rwx
default:group::r-x
default:mask::rwx
default:other::r-x


The -k switch removes the default acls

setfacl -k mary

getfacl mary
# file: mary
# owner: mary
# group: mary
user::rwx
user:john:rwx
user:mary:rwx
group::r-x
mask::rwx
other::r-x


Then remove john from it also
setfacl -x john mary

getfacl mary
# file: mary
# owner: mary
# group: mary
user::rwx
user:mary:rwx
group::r-x
mask::rwx
other::r-x

Repeat the same with other folder
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Monday, 7 February 2011

Redhat 6 - Part 1

Here are some new stuff in RHEL 6

Software versions
  • PHP 5.3.1. It also ships with APC (Alternative PHP Cache).
  • Apache is 2.2.14
  • MySQL is 5.1.42
  • Tomcat is 6.0.20
  • PostgreSQL is version 8.4
  • Python is 2.6
  • Perl is 5.10.1
  • Gcc is 44.4
File systems

Other Notable Changes
  • Default use of NFS v4
  • SysV init is gone in favour of upstart. Upstart comes with legacy support for traditional init scripts in /etc/init.d.
  • Support for Fibre Channel over Ethernet (FCoE)
  • iSCSI  can now be used as root or boot devices
  • As expected, Xen has been dropped in favour or KVM
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