SSH

1 Dosya indiriyorsun ve iptal etmek istiyosun?

• Just do a Ctrl-C

SSh Komutları: ls Dizinde bulunan her seyi listeler. ls -a Gizli dosyalar ve dizinlerle beraber listeler. ls -l Bütün dosyalari boyut ve tarihini göstererek listeler. tar -zxpf Uzantisi tar.gz olan sikistirilmis dosyalari acar. tar -xpf Uzantisi .tar olan dosyalari acar. gunzip Uzantisi .gz olan doslari acar. cp Dosyayi kopyalar. mv Bir dosyayi baska bir dizine tasimanizi saglar yada dosya adini degistirir. mkdir Yeni bir dizin olusturmanizi saglar. rmdir Belirtilen dizini silmenizi saglar. rm Dosya silmenizi saglar. rm -rf Dizin silmenizi saglar. cd Belirtilen dizine gecmenizi saglar. cd .. Bir üst dizine gecmenizi saglar. cd ~ En üst dizine cikmanizi saglar. pwd O anda bulundugunuz dizini görüntüler. pico Belirtilen dosyayi text editör ile düzenlemenizi saglar. ftp Belirtilen siteye FTP baglantisi saglar. lynx Belirtilen siteyi görüntüler. df Harddisk istatistiklerini gösterir. quota Disk kullaniminizi gösterir. uname isletim sisteiminin durumunu gösterir. whoami Kendi bilgilerinizi gösterir. who Sunucuya bagli olanlari gösterir. last Hesabiniza yapilan en son baglantiyi gösterir. whereis Belirtilen dosyanin nerede oldugunu gösterir. ps -x Sizin calistirdiginiz islemleri gösterir. ps -a Sunucuda calistirilan tüm islemleri gösterir. ps -ux calistirilan islemlerin CPU/RAM kullanimiyla gösterir. kill Pid numarasi verilen islemi durdurur. kill -9 Pid numarasi verilen eggdrop islemini durdurur. killall Belirtilen program türündeki tüm islemleri durdurur. whatis Belirtilen komutun aciklamasini verir. man Komut hakkinda yardim görüntüler passwd Shell hesabiniza girerken kullandiginiz sifreyi degistirmenizi saglar. vhosts yada vhost Sistemde bulunan vhostlari (virtual host) listeler.(BNC icin kullanabilirsiniz) reboot: Sunucuya restart atar service mysqld restart: mysql restart atar service httpd restart: apache ye rest atar service httpd stop : Sitelere ulasimi kapatir netstat -n : sunucuya baglanan ipleri gösterir netstat -a sunucuya baglanan reseller ipleri gösterir(Proxy kullanmaniz fark etmez her zaman gercek cikis ipi görünür) pico : ssh üzerinden text editor ile dosya icerigini görme ve düzenlemeye yarar. top : Sistem cpu kulalnimini gösterir. uptime : Uptime Durumu wget: wget www.siteadresi.com/dosyaadi seklinde sunucuya dosya cekmenizi saglar.

IP Engelleme

iptables -A INPUT -s 85.159.54.48 -j DROP ip ban kaldirma iptables -X INPUT -s 85.159.54.48 -j DROP

syn olarak sunucuya aldigini saldiri adetini ve ipleri gösterme

netstat -np | grep SYN_RECV | awk '{print $5}' | cut -d. -f1-4 | cut -d: -f1 | sort -n | uniq -c | sort -n

sunucu özellikleri

dmesg

SSH is a necessary tool in any server admin’s arsenal. It is the main way you will be interacting with your servers whenever you are performing system tasks such as install, updates, etc. SSH allows you to remotely connect to your server and command it via the shell. Below is a list of commands you will use commonly while working with your server.

I prefer the popular SSH client Putty, but any SSH client will do.

Common SSH Commands or Linux Shell Commands, ls : list files/directories in a directory, comparable to dir in windows/dos. ls -al : shows all files (including ones that start with a period), directories, and details attributes for each file.

cd : change directory · · “cd /home/username/” will navigate to /home/username/ directory cd ~ : go to your home directory cd - : go to the last directory you were in cd .. : go up a directory cat : print file contents to the screen

cat filename.txt : cat the contents of filename.txt to your screen

chmod: changes file access permissions The set of 3 go in this order from left to right: USER – GROUP – EVERONE

0 = — No permission 1 = –X Execute only 2 = -W- Write only 3 = -WX Write and execute 4 = R– Read only 5 = R-X Read and execute 6 = RW- Read and write 7 = RWX Read, write and execute

Usage: chmod numberpermissions filename

chmod 000 : No one can access chmod 644: Usually for HTML pages chmod 755: Usually for CGI scripts

chown: changes file ownership permissions The set of 2 go in this order from left to right: USER – GROUP

chown root myfile.txt : Changes the owner of the file to root chown root.root myfile.txt : Changes the owner and group of the file to root

tail : like cat, but only reads the end of the file tail /var/log/messages : see the last 20 (by default) lines of /var/log/messages tail -f /var/log/messages : watch the file continuously, while it’s being updated tail -200 /var/log/messages : print the last 200 lines of the file to the screen

more : like cat, but opens the file one screen at a time rather than all at once more /etc/userdomains : browse through the userdomains file. hit Spaceto go to the next page, q to quit

pico : friendly, easy to use file editor pico /home/burst/public_html/index.html : edit the index page for the user’s website.

File Editing with VI ssh commands vi : another editor, tons of features, harder to use at first than pico vi /home/burst/public_html/index.html : edit the index page for the user’s website. Whie in the vi program you can use the following useful commands, you will need to hit SHIFT + : to go into command mode

:q! : This force quits the file without saving and exits vi :w : This writes the file to disk, saves it :wq : This saves the file to disk and exists vi :LINENUMBER : EG :25 : Takes you to line 25 within the file :$ : Takes you to the last line of the file :0 : Takes you to the first line of the file

grep : looks for patterns in files grep root /etc/passwd : shows all matches of root in /etc/passwd grep -v root /etc/passwd : shows all lines that do not match root

ln : create’s “links” between files and directories ln -s /usr/local/apache/conf/httpd.conf /etc/httpd.conf : Now you can edit /etc/httpd.conf rather than the original. changes will affect the orginal, however you can delete the link and it will not delete the original.

last : shows who logged in and when last -20 : shows only the last 20 logins last -20 -a : shows last 20 logins, with the hostname in the last field

w : shows who is currently logged in and where they are logged in from. who : This also shows who is on the server in an shell.

netstat : shows all current network connections. netstat -an : shows all connections to the server, the source and destination ips and ports. netstat -rn : shows routing table for all ips bound to the server.

top : shows live system processes in a nice table, memory information, uptime and other useful info. This is excellent for managing your system processes, resources and ensure everything is working fine and your server isn’t bogged down. top then type Shift + M to sort by memory usage or Shift + P to sort by CPU usage

ps: ps is short for process status, which is similar to the top command. It’s used to show currently running processes and their PID. A process ID is a unique number that identifies a process, with that you can kill or terminate a running program on your server (see kill command). ps U username : shows processes for a certain user ps aux : shows all system processes ps aux –forest : shows all system processes like the above but organizes in a hierarchy that’s very useful!

touch : create an empty file touch /home/burst/public_html/404.html : create an empty file called 404.html in the directory /home/burst/public_html/

file : attempts to guess what type of file a file is by looking at it’s content. file * : prints out a list of all files/directories in a directory

du : shows disk usage. du -sh : shows a summary, in human-readble form, of total disk space used in the current directory, including subdirectories. du -sh * : same thing, but for each file and directory. helpful when finding large files taking up space.

wc : word count wc -l filename.txt : tells how many lines are in filename.txt

cp : copy a file cp filename filename.backup : copies filename to filename.backup cp -a /home/burst/new_design/* /home/burst/public_html/ : copies all files, retaining permissions form one directory to another. cp -av * ../newdir : Copies all files and directories recurrsively in the current directory INTO newdir

mv : Move a file command mv oldfilename newfilename : Move a file or directory from oldfilename to newfilename

rm : delete a file rm filename.txt : deletes filename.txt, will more than likely ask if you really want to delete it rm -f filename.txt : deletes filename.txt, will not ask for confirmation before deleting. rm -rf tmp/ : recursively deletes the directory tmp, and all files in it, including subdirectories. BE VERY CAREFULL WITH THIS COMMAND!!!

TAR: Creating and Extracting .tar.gz and .tar files tar -zxvf file.tar.gz : Extracts the file tar -xvf file.tar : Extracts the file tar -cf archive.tar contents/ : Takes everything from contents/ and puts it into archive.tar gzip -d filename.gz : Decompress the file, extract it

ZIP Files: Extracting .zip files shell command unzip file.zip

Firewall - iptables commands iptables -I INPUT -s IPADDRESSHERE -j DROP : This command stops any connections from the IP address iptables -L : List all rules in iptables iptables -F : Flushes all iptables rules (clears the firewall) iptables –save : Saves the currenty ruleset in memory to disk service iptables restart : Restarts iptables

Apache Shell Commands httpd -v : Outputs the build date and version of the Apache server. httpd -l : Lists compiled in Apache modules httpd status : Only works if mod_status is enabled and shows a page of active connections service httpd restart : Restarted Apache web server

MySQL Shell Commands mysqladmin processlist : Shows active mysql connections and queries mysqladmin drop databasenamehere : Drops/deletes the selected database mysqladmin create databasenamehere : Creates a mysql database

Restore MySQL Database Shell Command mysql -u username -p password databasename < databasefile.sql : Restores a MySQL database from databasefile.sql

Backup MySQL Database Shell Command mysqldump -u username -p password databasename > databasefile.sql : Backup MySQL database to databasefile.sql

kill: terminate a system process kill -9 PID EG: kill -9 431 kill PID EG: kill 10550 Use top or ps ux to get system PIDs (Process IDs)

EG:

PID TTY TIME COMMAND 10550 pts/3 0:01 /bin/csh 10574 pts/4 0:02 /bin/csh 10590 pts/4 0:09 APP Each line represents one process, with a process being loosely defined as a running instance of a program. The column headed PID (process ID) shows the assigned process numbers of the processes. The heading COMMAND shows the location of the executed process.

Putting commands together Often you will find you need to use different commands on the same line. Here are some examples. Note that the | character is called a pipe, it takes date from one program and pipes it to another.

means create a new file, overwriting any content already there.

means tp append data to a file, creating a newone if it doesn not already exist. < send input from a file back into a command.

grep User /usr/local/apache/conf/httpd.conf |more This will dump all lines that match User from the httpd.conf, then print the results to your screen one page at a time.

last -a > /root/lastlogins.tmp This will print all the current login history to a file called lastlogins.tmp in /root/

tail -10000 /var/log/exim_mainlog |grep domain.com |more This will grab the last 10,000 lines from /var/log/exim_mainlog, find all occurances of domain.com (the period represents ‘anything’, – comment it out with a so it will be interpretted literally), then send it to your screen page by page.

netstat -an |grep :80 |wc -l Show how many active connections there are to apache (httpd runs on port 80)

mysqladmin processlist |wc -l Show how many current open connections there are to mysql