vnix27's questions

I wrote following script, which generate random password and store it in file

pass1=</dev/urandom tr -dc _A-Z-a-z-0-9|head -c8
echo $pass1
echo "$pass1" >/tmp/a

Above script printing generated password through "echo $pass1" command. But nothing getting stored inside created /tmp/a file .

Please let me know whats wrong i am doing.

I am getting following disk error on one of my server

smartd[4235]: Device: /dev/sda, 1 Currently unreadable (pending) sectors

Can i apply following command to repair bad block on live RHEL5 system .

badblocks -n -v /dev/hda1

I have a server with NFS, LDAP, and Autofs configured for export the /home, but every time i try mount nfs in my client desktop, the receive this error in Server: Cannot export /home, possibly unsupported filesystem or fsid= required. I am using the command mount -t nfs server:/home for testing the export of /home directory.

My config files Server

#/etc/auto.master
/home auto.home
#auto.home
* -fstype=nfs,rw server:/home/&
# /etc/exports
/home *(rw,fsid=0)

Someone can please help me ?

I am getting following error while trying to use mailstats command

mailstats version (3) incompatible with /etc/mail/statistics version (4).

Can anyone please advise how i can overcome this error

One of process invaded my system. I traced that process id, and wanted to dump /proc/pid/exe to that i can investigate later. Please advice how i take dump of /proc/pid/exe

I have a requirement to raise alert when a particular process(suppose abc) start or stop. One of idea is to write a script that monitor process , Can you suggest any better idea. I can't install any additional tools or softwares .

On one of CentOS server i found that load is around 10 , vmstat output says a large number of process are in blocking state. In top command output, cpu is almost 70% idel. What i conclude from my investigation that may be a large number of process saturated system . Now i decided to limit nproc by making entries in /etc/security/limits.conf

Am i on right track of troubleshooting ?

I received a complain that my system doing invalid ssh attempt. I did my investigation and found nothing related log entries. But one thing that surprised me that executing command

rpm -qa|xargs rpm -V|grep ^S

listed /usr/sbin/suexec as S .5....T /usr/sbin/suexec

Does this indicate that my system or Apache become compromised . Please guide me, as I found there is currently no outbound ssh traffic, but logs on the victim system indicate there has been in the past past.

I need to calculate time difference between two log messages of /var/log/messages. As we know log messages prefixed by date & time , i want time difference between two log entries.

I have a file that has a list of "bad" IP addresses. I want to import this file of bad IP addresses into my .htaccess file to deny access via apache.

I want to automate this process using sed. How would I go about doing this?

I want to log IP Address of clients which tried to access my site , but unable due to blocking in .htaccess using DENY FROM syntax .
Please guide me

Suggest me best way to list io bounded process. I know iotop is best way to get list but want any alternate option since my system showing a large number of D state process.

What is difference between $* and $@ positional variable in linux. I read somewhere using $* is is security risk. Is it true.

What is the best way to kill Zombie processes and D state process by single command.

I wrote following line in my script , but it not assigning any value to variable a

a= grep -n mark /etc/samba/smb.conf |cut -d: f1

I aspect line number where mark string present in smb.conf in variable a. But value of variable is null. What may be the issue

I open a text file using vi editor in linux and want to insert date command output without exiting vi editor. What is the trick?

Thanks

I am using vsftpd as ftp server on rhel 5. I published a folder using ftp and try to access that folder using ftp client FileZilla. The problem is that filezilla shows physical path of ftp folder. This can be a security concern.

Please suggest me any workaround

I am trying to list deleted files from my ext3 file system. debugsfs command with -ld option , suppose to list deleted files but it only listing current existing files and folder. Is any alternate way without any third party tools to recover deleted files .

Thanks

Is there any method to log vi activities? I suspect that another user is issuing commands by going into the shell inside the vi editor, apparently those command doesn't record into history.

I am using vsftpd installed on RHEL5.

I need to get the current logged on ftp users, so I issued last|grep 'still' but it didn't display the ftp users. What is the command to achieve this?