GFS module in CentOS RPM

How to check if the kernel you have in the server has gfs modules?

When i was installing gfs support in one of my servers i wanted to check whether the kernel i used was having gfs modules. Without that i cannot make gfs work. It was simple to find out.

After installing the kernel and gfs rpms, just list the files under the kernel modules directory:

# cd /lib/modules/2.6.9-55.0.2.ELsmp
# ls kernel/fs/
autofs4  cramfs    ext3  freevxfs  gfs_locking  hfsplus  jffs2  msdos  nfs_common  nls    udf
cifs     exportfs  fat   gfs       hfs          jbd      lockd  nfs    nfsd        smbfs  vfat

You can even list the files in gfs and gfs_locking directories

# ls kernel/fs/gfs
gfs.ko

# ls kernel/fs/gfs_locking/
lock_dlm  lock_gulm  lock_harness  lock_nolock

It will be tricky if you want other modules like xfs. You need to find a kernel RPM that has both xfs & gfs module rpms or if you have time to play you can compile them all yourselves.

Vsftpd and iptables

In one of our servers we were running vsftpd service. iptables was setup to allow ports 21 and 20(data). Still after the user logs in, the connection dies when trying to enter passive mode.

Entry: /sbin/modprobe ip_conntrack_ftp

was already there in /etc/rc.local

still the module was not loaded by default, Since iptables unloas all modules automatically everytime it starts.

Change the below lines to change this behavior:

ip_conntrack_ftp       76273  0
ip_conntrack           45573  1 ip_conntrack_ftp
IPTABLES_MODULES_UNLOAD="no"    # Makes all modules to be persistent

Restart the service and check whether the conntrack module is loaded

# service iptables restart
# lsmod|grep ip_conntrack

Worked liked charm. Now i could login to the ftp service and enter passive mode.