Updated: 2014-03-31 12:24 EDT
Do not print this assignment on paper!
- On paper, you will miss updates, corrections, and hints added to the online version.
- On paper, you cannot follow any of the hyperlink URLs that lead you to hints and course notes relevant to answering a question.
- On paper, scrolling text boxes will be cut off and not print properly.
10h00 (10am) Monday April 7, 2014 (start of Week 13)
auth.log
and 1 10 86 for denyhosts
(thanks to Sam)WARNING: Some inattentive students upload Assignment #11 into the Assignment #10 upload area. Don’t make that mistake! Be exact.
Do not print this assignment on paper! On paper, you cannot follow any of the hyperlink URLs that lead you to hints and course notes relevant to answering a question.
This assignment is based on your weekly Class Notes.
cron
and at
Remember to READ ALL THE WORDS to work effectively and not waste time.
This is an overview of how you are expected to complete this assignment. Read all the words before you start working.
Practice controlling Processes and Jobs.
Search System Log Files.
Schedule jobs using Crontab and At.
Review minimal permissions from Worksheet #08.
You will create file system structure in your CLS home directory containing various directories and files. You can use the Checking Program to check your work as you do the tasks. You can check your work with the checking program as often as you like before you submit your final mark. Some task sections below require you to finish the whole section before running the checking program; you may not always be able to run the checking program successfully after every single task step.
When you are finished the tasks, leave the files and directories in place on both the CLS as part of your deliverables. Do not delete any assignment work until after the term is over! Assignments may be re-marked at any time on the CLS; you must have your term work available on the CLS right until term end.
All references to the “Source Directory” below are to the CLS directory ~idallen/cst8207/14w/assignment11/
and that name starts with a tilde character followed by a userid with no intervening slash. The leading tilde indicates to the shell that the pathname starts with the HOME directory of the account idallen
(seven letters).
You do not have permission to list the names of all the files in the Source Directory, but you can access any files whose names you already know.
Do a Remote Login to the Course Linux Server (CLS) from any existing computer, using the host name appropriate for whether you are on-campus or off-campus.
Make the directory ~/CST8207-14W/Assignments/assignment11
, in which you will create the files and scripts resulting from the following tasks.
Create the check
symbolic link needed to run the Checking Program, as described in the section Checking Program below.
This assignment11
directory is the base directory for most pathnames in this assignment. Store your files and answers below in this base assignment11
directory.
Run the Checking Program on the CLS to verify your work so far.
Review Processes and Jobs.
Place a full list of all processes for all users, BSD format, all users, text user name (not numeric UID), full wide listing (not truncated at all), into file psbsd.txt
in your assignment11
directory. It should be “at least” 105 lines and 9KB. The header line and one of the very long lines will be a dhclient
line similar to this (use a text-searching command to find it in the output):
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 4312 0.0 0.0 7268 328 ? Ss Mar15 0:00 dhclient3 -e IF_METRIC=9999 -pf /var/run/dhclient.eth0.pid -lf /var/lib/dhcp/dhclient.eth0.leases -1 eth0
Place a full list of all processes for all users, UNIX (System V) format, text user name (not numeric UID), full wide listing (not truncated at all), into file psunix.txt
in your assignment11
directory. It should be “at least” 105 lines and 7KB. The header line and one of the very long lines will be a dhclient
line similar to this (use a text-searching command to find it in the output):
UID PID PPID C STIME TTY TIME CMD
root 4312 1 0 Mar15 ? 00:00:00 dhclient3 -e IF_METRIC=9999 -pf /var/run/dhclient.eth0.pid -lf /var/lib/dhcp/dhclient.eth0.leases -1 eth0
Pick off the first line (the header line) of the psbsd.txt
file and put the one line into file mine.txt
. (1 11 73 mine.txt
)
Find all lines in psbsd.txt
that contain your userid anywhere in the line and append those lines to the mine.txt
file.
Run the Checking Program on the CLS to verify your work so far.
Review System Log Files.
What is the actual name of the syslog program on the CLS? Search for and extract the one line from each file psbsd.txt
and psunix.txt
that contains this name and redirect the results (two lines, one from each file) into file syslog.txt
. (The result will be 2 lines, 21 words.)
The system authentication log file is named auth.log
in the system log directory. Generate an ls
long listing of this file using the full absolute pathname, and put the results of the ls
(the output of ls
) into file authlog.txt
. (The result of the ls
command should be 1 line, 9 words, at least 60 characters.)
(Optional: You may find it convenient to set a shell variable to this absolute pathname, so that you can use the short variable name rather than the long absolute pathname in the rest of these exercises. Or, you could make a short symbolic link to this file.)
Use one command to put a list (one line) of your numeric uid, your userid, your numeric gid, your group name, and your additional group names into the file id.txt
. The result will be 1 (long) line, 3 words. (See Permissions for the command to use to do this. Do not edit the output of the command.)
Look at the contents of the id.txt
and authlog.txt
files. Note that your account is in a group that matches the group of the system auth.log
file, giving you group permissions on this file. Using a text editor, put the matching group name (three characters), the symbolic group permissions (three characters), and the octal group permissions (one digit), onto three lines in file myperms.txt
. (The result will be 3 lines, 3 words, 10 characters. Do you remember why a line containing seven alphanumeric characters on three lines is counted as a 10-character file?)
The system auth.log
file contains over 1,858,190 lines. Use a command to extract just the first line (one line) from the head of this file and redirect that one line into new file authhead.txt
. (The result will be 1 line 13 words 111 chars.) The time and date at the start of this line is when this copy of the log file was started.
If you count the number of lines in the system auth.log
containing the exact text string Failed password
, the count is more than 4,060 lines. Of those lines (the lines containing that text string), extract just lines 100 through 110 (inclusive) and put those 11 lines into file failedpass.txt
. The word count for the file will be 11 164 1214
. Every line should contain the text string somewhere.
The CLS is running the denyhosts
package to blacklist attacking machines. It logs its activity in the expected denyhosts
log file. There are over 340 lines containing the exact three-word string new denied host
in this file. Of those lines containing that string, select just the one line that was logged on March 5, 2014 and redirect that one line into file badhost.txt
(word count 1 10 86
). Hint: You did a similar search in Assignment #06. Use a pipeline with two text-finding commands to find the only line that matches both the date and the desired text. You will need to search for the date in the format that it appears in the log file.
In the auth.log
file search for all lines containing the IP address of the attacking machine (that IP address is the one IP address in the one line you just put in badhost.txt
) to find out why that IP address was blacklisted. Redirect the output into file badauth.txt
. The result will be at least 11 lines 137 words 1234 characters. (It may be more, if they attack again!) Every line of output will contain that attacking IP address somewhere in the line.
Warning! Do not run the whois
command more than absolutely necessary, since too many uses may result in us being cut off from using the whois
database! Run the command and save the output in to a temporary file, then extract the needed information from that temporary file rather than running the command again.
Run the whois
command (once!) and find out where this attacking IP address originates. Put the four output lines from whois
containing the string address:
into file badaddr.txt
. The result will count as 4 21 188
.
Feel free to explore some other attacking IP addresses in the denyhosts
log file to learn what it’s like having a machine exposed on the Internet. (But please be selective about using the whois
command!)
Run the Checking Program on the CLS to verify your work so far.
Review Crontab and At.
Create a personal crontab
entry that uses a command to update the modification time on file crontab.txt
in your assignment11
directory (not in your HOME
directory) every minute of every day. Use the shortest relative pathname to your crontab.txt
file. Do not use an absolute pathname. Verify that the modification time of the file changes every minute.
If it doesn’t work, read your Linux email for email messages from the Cron daemon showing possible errors. See Reading eMail for help.
List your personal crontab
(one entry) and redirect the output into file crontab1.txt
.
Delete your personal crontab
.
Create a personal crontab
entry that updates the modification time on the same file crontab.txt
at exactly 7:34 PM on the 20th day of every month. (Also use a relative pathname, not an absolute pathname.)
List your personal crontab
(one entry) and redirect the output into file crontab2.txt
. Do not delete this crontab
entry; leave it for marking.
Create an at
job that updates the modification time on the file atjob.txt
(in your assignment11
directory, not in your HOME
directory) one or two minutes from now. (Check the current system time and add a minute or two. Look at the queue of at
jobs and make sure the scheduled job time is correct.) Make sure that the file time changes one or two minutes from now.
If it doesn’t work, check the queue of at
jobs and make sure the job isn’t queued later than you think it is. Also, read your Linux email for email messages from the At daemon showing possible errors. See Reading eMail for help.
Make assignment11
your current directory and then create an at
job that updates the modification time on the file atjob.txt
(in your current directory, not in your HOME
directory) at the start date and time of your CST8207 final exam. See the Crontab and At course notes or RTFM to find out how to specify both a time and a date.
Again, check the queue of at
jobs and make sure the scheduled time is correct. Leave this job queued on the CLS for marking.
Display all your queued at
jobs and redirect the output into file atjob.txt
. (You will only have one job – one line.) (If you have more than one line, delete the other jobs first.)
Read your CLS Linux email and remove any messages that may be waiting. See Reading eMail for help.
Run the Checking Program on the CLS to verify your work so far.
tar
archiveIndexOn the CLS go to your Assignments
directory.
tar
archive of your assignment11
directory named assignment11_
YYYYMMDD.tgz
(no spaces), where YYYYMMDD is the date you created the archive backup.
tar
file must not include any parent directories of the assignment11
directory you were asked to save.Move the archive you just created into your assignment11
directory.
Generate a verbose listing of your tar
archive file, showing the contents of the archive including all the owners and date/time stamps, into file tar_tvzf.txt
under your assignment11
directory.
Optional: Read the mouse-over text in this tar
-related comic from the XKCD webcomic.
Run the Checking Program on the CLS to verify your work so far.
That is all the tasks you need to do.
Check your work a final time using the Checking Program and save the output as described below. Submit your mark following the directions below.
Summary: Do some tasks, then run the checking program to verify your work as you go. You can run the checking program as often as you want. When you have the best mark, upload the marks file to Blackboard.
Since I also do manual marking of student assignments, your final mark may not be the same as the mark submitted using the current version of the Checking Program. I do not guarantee that any version of the Checking Program will find all the errors in your work. Complete your assignments according to the specifications, not according to the incomplete set of the mistakes detected by the Checking Program.
There is a Checking Program named assignment11check
in the Source Directory on the CLS. Create a Symbolic Link to this program named check
under your new assignment11
directory on the CLS so that you can easily run the program to check your work and assign your work a mark on the CLS. Note: You can create a symbolic link to this executable program but you do not have permission to read or copy the program file.
Execute the above “check” program on the CLS using its symbolic link. (Review the Search Path notes if you forget how to run a program by pathname from the command line.) This program will check your fetched CentOS work, assign you a mark, and display the output on your screen. (You may want to paginate the long output so you can read all of it.)
You may run the “check” program as many times as you wish, to correct mistakes and get the best mark. Some task sections require you to finish the whole section before running the checking program at the end; you may not always be able to run the checking program successfully after every single task step.
assignment11.txt
under your assignment11
directory on the CLS. Use the exact name assignment11.txt
in your assignment11
directory. Case (upper/lower case letters) matters. Be absolutely accurate, as if your marks depended on it. Do not edit the file.
YOUR MARK for
assignment11.txt
file from the CLS to your local computer and verify that the file still contains all the output from the checking program. Do not edit this file! No empty files, please! Edited or damaged files will not be marked. You may want to refer to your File Transfer notes.
YOUR MARK for
Upload the assignment11.txt
file under the correct Assignment area on Blackboard (with the exact name) before the due date. Upload the file via the assignment11 “Upload Assignment” facility in Blackboard: click on the underlined assignment11 link in Blackboard. Use “Attach File” and “Submit” to upload your plain text file.
No word-processor documents. Do not send email. Use only “Attach File”. Do not enter any text into the Submission or Comments boxes on Blackboard; I do not read them. Use only the “Attach File” section followed by the Submit button. If you need to comment on any assignment submission, send me email.
You can upload the file more than once; I only look at the most recent. You must upload the file with the correct name; you cannot correct the name as you upload it to Blackboard.
You will also see the Review Submission History page any time you already have an assignment attempt uploaded and you click on the underlined assignment11 link.
You cannot delete an assignment attempt, but you can always upload a new version. I only mark the latest version.
Your instructor may also mark files in your directory in your CLS account after the due date. Leave everything there on the CLS. Do not delete any assignment work from the CLS until after the term is over!
I do not accept any assignment submissions by email. Use only the Blackboard Attach File. No word processor documents. Plain Text only.
Use the exact file name given above. Upload only one single file of Linux-format plain text, not HTML, not RTF, not MSWord. No fonts, no word-processing. Linux plain text only.
NO EMAIL, WORD PROCESSOR, PDF, RTF, or HTML DOCUMENTS ACCEPTED.
No marks are awarded for submitting under the wrong assignment number or for using the wrong file name. Use the exact 16-character, lower-case name given above.
WARNING: Some inattentive students don’t read all these words. Don’t make that mistake! Be exact.
READ ALL THE WORDS. OH PLEASE, PLEASE, PLEASE READ ALL THE WORDS!