ProsNcons of Linux: January 2015

Saturday, January 24, 2015

unecrypted connection refused. Goodbye !

When I telnet my server I get "Unencrypted connection refused. Goodbye".

solution :

[root@localhost init.d]# /sbin/chkconfig --list |grep telnet
ekrb5-telnet: on //This should be off
krb5-telnet: off
telnet: on
[root@localhost init.d]# /sbin/chkconfig ekrb5-telnet off
[root@localhost init.d]# /sbin/chkconfig --list |grep telnet
ekrb5-telnet: off
krb5-telnet: off
telnet: on
[root@localhost init.d]# telnet 0.0
Trying 0.0.0.0...
Connected to 0.0 (0.0.0.0).
Escape character is '^]'.
Red Hat Enterprise Linux Server release 5.5 Beta (Tikanga)
Kernel 2.6.18-189.el5 on an i686
login: root
Password:
Last login: Fri Jxxxxxxxxxxxxxxxxxxxx
[root@localhost ~]#

Aslo ,
telnet-server package need to be installed .

Friday, January 23, 2015

Regarding STDERR STDOUT STDIN

crontab -l
sh /root/ntp.sh >>/dev/null 2>&1

There are three standard sources of input and output for a program

> STDIN :0
> STDOUT :1
> STDERR : 2

Sometimes they’re not named, they’re numbered! The built-in numberings for them are 0, 1, and 2,
in that order. By default, if you don’t name or number one explicitly, you’re talking about STDOUT.

Ques :
Disable Email By default cron jobs sends an email to the user account executing the cronjob.
If this is not needed put the following command At the end of the cron job line.

>/dev/null 2>&1

Ans :

> is for redirect

/dev/null is a black hole where any data sent, will be discarded

2 is the file descriptor for Standard Error

> is for redirect

& is the symbol for file descriptor (without it, the following 1 would be considered a filename)

1 is the file descriptor for Standard Out

Therefore >/dev/null 2>&1 is redirect the output of your program to /dev/null. Include both the Standard Error and Standard Out.

AS WELL AS ,

/dev/null is a device file that acts like a blackhole. Whatever that is written to it, get discarded or disappears. When you run a script that gives you an output and if we add a > /dev/null 2>&1 at the end of the script, we are asking the script to write whatever that is generated from the script (both the output and error messages) to /dev/null.

To break it up:

2 is the handle for standard error or STDERR
1 is the handle for standard output or STDOUT
2>&1 is asking to direct all the STDERR as STDOUT, (ie. to treat all the error messages generated from the script as its standard output). Now we already have > /dev/null at the end of the script which means all the standard output (STDOUT) will be written to /dev/null. Since STDERR is now going to STDOUT (because of 2>&1) both STDERR and STDOUT ends up in the blackhole /dev/null. In other words, the script is silenced.

By the way, you need to have a > in front of /dev/null 2>&1. It should be:

* * * * * /path/to/my/script > /dev/null 2>&1

NTP configuration on Windows 2012

source

Configure Windows Server 2012 As An NTP Server

When you’re configuring a Mac to leverage an existing Windows infrastructure, having the clocks in sync is an important task. Luckily, Windows Server has been able to act as an NTP server for a long time. In this article, we’ll look at configuring Windows Server to be an NTP server for Mac and Linux clients.

Note: Before you get started, or any time you’re hacking around in the registry, make sure to do a backup of your registry/SystemState!

To enable NTP on Windows Server, open your favorite registry editor and navigate to HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpServer. From here, enter a key called Enabled as a dword with a value of 00000001.

The NTP Server should look upstream at another NTP host. To configure this, go ahead and navigate to HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpClient and create Enabled as a dword with a value of 0000001 and SpecialPollInterval with a value of 300:

“Enabled”=dword:00000001
“SpecialPollInterval”=”300″

NTP would then need a source, so let’s go ahead and create that in the registry as well. To set that up, navigate to HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeParameters and then setup the Type key to contain NTP, the Period key to contain freq and the NtpServer key to obtain the IP address of the server followed by ,0x1, as follows (assuming an IP of 10.0.0.8 for the upstream NTP server:

“NtpServer”=10.0.0.8,0×1″
“Type”=”NTP”
“Period”=”freq”

The w32tm service doesn’t start unless your system is on a domain (and should be restarted if the system is already running as a DC). To starts the service automatically (if needed), use the sc command:

sc triggerinfo w32time start/networkon stop/networkoff

Windows systems can also use an NTP server. To configure the NTP client, navigate to HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeTimeProvidersNtpClient and create Enabled as a dword with a value of 0000001 and SpecialPollInterval with a value of 300:

“Enabled”=dword:00000001
“SpecialPollInterval”=”300″

“NtpServer”=10.0.0.8,0×1″
“Type”=”NTP”
“Period”=”freq”

Finally, you can invoke the w32tm service directly to query peers and verify that no skew has occurred with the clocks:

w32tm /query /peers

Sunday, January 11, 2015

NMON usage

1. Scan a System with Hostname and IP Address

The Nmap tool offers various methods to scan a system. In this example, I am performing a scan using hostname as server2.tecmint.com to find out all open ports, services and MAC address on the system.

Scan using Hostname

[root@server1 ~]# nmap server2.tecmint.com

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 15:42 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.415 seconds
You have new mail in /var/spool/mail/root

Scan using IP Address

[root@server1 ~]# nmap 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-18 11:04 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
958/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.465 seconds
You have new mail in /var/spool/mail/root

2. Scan using “-v” option

You can see that the below command with “-v” option is giving more detailed information about the remote machine.

[root@server1 ~]# nmap -v server2.tecmint.com

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 15:43 EST
Initiating ARP Ping Scan against 192.168.0.101 [1 port] at 15:43
The ARP Ping Scan took 0.01s to scan 1 total hosts.
Initiating SYN Stealth Scan against server2.tecmint.com (192.168.0.101) [1680 ports] at 15:43
Discovered open port 22/tcp on 192.168.0.101
Discovered open port 80/tcp on 192.168.0.101
Discovered open port 8888/tcp on 192.168.0.101
Discovered open port 111/tcp on 192.168.0.101
Discovered open port 3306/tcp on 192.168.0.101
Discovered open port 957/tcp on 192.168.0.101
The SYN Stealth Scan took 0.30s to scan 1680 total ports.
Host server2.tecmint.com (192.168.0.101) appears to be up ... good.
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.485 seconds
               Raw packets sent: 1681 (73.962KB) | Rcvd: 1681 (77.322KB)

Scan Multiple Hosts

You can scan multiple hosts by simply writing their IP addresses or hostnames with Nmap.

[root@server1 ~]# nmap 192.168.0.101 192.168.0.102 192.168.0.103

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:06 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)
Nmap finished: 3 IP addresses (1 host up) scanned in 0.580 seconds

4. Scan a whole Subnet

You can scan a whole subnet or IP range with Nmap by providing * wildcard with it.

[root@server1 ~]# nmap 192.168.0.*

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:11 EST
Interesting ports on server1.tecmint.com (192.168.0.100):
Not shown: 1677 closed ports
PORT    STATE SERVICE
22/tcp  open  ssh
111/tcp open  rpcbind
851/tcp open  unknown

Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 256 IP addresses (2 hosts up) scanned in 5.550 seconds
You have new mail in /var/spool/mail/root

On above output you can see that nmap scanned a whole subnet and gave the information about those hosts which are Up in the Network.

5. Scan Multiple Servers using last octet of IP address

You can perform scans on multiple IP address by simple specifying last octet of IP address. For example, here I performing a scan on IP addresses 192.168.0.101, 192.168.0.102 and 192.168.0.103.

[root@server1 ~]# nmap 192.168.0.101,102,103

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:09 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 3 IP addresses (1 host up) scanned in 0.552 seconds
You have new mail in /var/spool/mail/root

6. Scan list of Hosts from a File

If you have more hosts to scan and all host details are written in a file , you can directly ask nmap to read that file and perform scans. Let’s see how to do that.

Create a text file called “nmaptest.txt” and define all the IP addresses or hostname of the server that you want to do a scan.

[root@server1 ~]# cat > nmaptest.txt

localhost
server2.tecmint.com
192.168.0.101

Next, run the following command with “iL” option with nmap command to scan all listed IP address in the file.

[root@server1 ~]# nmap -iL nmaptest.txt

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-18 10:58 EST
Interesting ports on localhost.localdomain (127.0.0.1):
Not shown: 1675 closed ports
PORT    STATE SERVICE
22/tcp  open  ssh
25/tcp  open  smtp
111/tcp open  rpcbind
631/tcp open  ipp
857/tcp open  unknown

Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
958/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
958/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 3 IP addresses (3 hosts up) scanned in 2.047 seconds

7. Scan an IP Address Range

You can specify an IP range while performing scan with Nmap.

[root@server1 ~]# nmap 192.168.0.101-110

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:09 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 10 IP addresses (1 host up) scanned in 0.542 seconds

8. Scan Network Excluding Remote Hosts

You can exclude some hosts while performing a full network scan or when you are scanning with wildcards with “–exclude” option.

[root@server1 ~]# nmap 192.168.0.* --exclude 192.168.0.100

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:16 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 255 IP addresses (1 host up) scanned in 5.313 seconds
You have new mail in /var/spool/mail/root

9. Scan OS information and Traceroute

With Nmap, you can detect which OS and version is running on the remote host. To enable OS & version detection, script scanning and traceroute, we can use “-A” option with NMAP.

[root@server1 ~]# nmap -A 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:25 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE VERSION
22/tcp   open  ssh     OpenSSH 4.3 (protocol 2.0)
80/tcp   open  http    Apache httpd 2.2.3 ((CentOS))
111/tcp  open  rpcbind  2 (rpc #100000)
957/tcp  open  status   1 (rpc #100024)
3306/tcp open  mysql   MySQL (unauthorized)
8888/tcp open  http    lighttpd 1.4.32
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)
No exact OS matches for host (If you know what OS is running on it, see http://www.insecure.org/cgi-bin/nmap-submit.cgi).
TCP/IP fingerprint:
SInfo(V=4.11%P=i686-redhat-linux-gnu%D=11/11%Tm=52814B66%O=22%C=1%M=080027)
TSeq(Class=TR%IPID=Z%TS=1000HZ)
T1(Resp=Y%DF=Y%W=16A0%ACK=S++%Flags=AS%Ops=MNNTNW)
T2(Resp=N)
T3(Resp=Y%DF=Y%W=16A0%ACK=S++%Flags=AS%Ops=MNNTNW)
T4(Resp=Y%DF=Y%W=0%ACK=O%Flags=R%Ops=)
T5(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
T6(Resp=Y%DF=Y%W=0%ACK=O%Flags=R%Ops=)
T7(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
PU(Resp=Y%DF=N%TOS=C0%IPLEN=164%RIPTL=148%RID=E%RIPCK=E%UCK=E%ULEN=134%DAT=E)

Uptime 0.169 days (since Mon Nov 11 12:22:15 2013)

Nmap finished: 1 IP address (1 host up) scanned in 22.271 seconds
You have new mail in /var/spool/mail/root

In above Output, you can see that nmap is came up with TCP/IPfingerprint of the OS running on remote hosts and being more specific about the port and services running on the remote hosts.

10. Enable OS Detection with Nmap

Use the option “-O” and “-osscan-guess” also helps to discover OS information.

[root@server1 ~]# nmap -O server2.tecmint.com

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 17:40 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)
No exact OS matches for host (If you know what OS is running on it, see http://www.insecure.org/cgi-bin/nmap-submit.cgi).
TCP/IP fingerprint:
SInfo(V=4.11%P=i686-redhat-linux-gnu%D=11/11%Tm=52815CF4%O=22%C=1%M=080027)
TSeq(Class=TR%IPID=Z%TS=1000HZ)
T1(Resp=Y%DF=Y%W=16A0%ACK=S++%Flags=AS%Ops=MNNTNW)
T2(Resp=N)
T3(Resp=Y%DF=Y%W=16A0%ACK=S++%Flags=AS%Ops=MNNTNW)
T4(Resp=Y%DF=Y%W=0%ACK=O%Flags=Option -O and -osscan-guess also helps to discover OS
R%Ops=)
T5(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
T6(Resp=Y%DF=Y%W=0%ACK=O%Flags=R%Ops=)
T7(Resp=Y%DF=Y%W=0%ACK=S++%Flags=AR%Ops=)
PU(Resp=Y%DF=N%TOS=C0%IPLEN=164%RIPTL=148%RID=E%RIPCK=E%UCK=E%ULEN=134%DAT=E)

Uptime 0.221 days (since Mon Nov 11 12:22:16 2013)

Nmap finished: 1 IP address (1 host up) scanned in 11.064 seconds
You have new mail in /var/spool/mail/root

11. Scan a Host to Detect Firewall

The below command will perform a scan on a remote host to detect if any packet filters or Firewall is used by host.

[root@server1 ~]# nmap -sA 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:27 EST
All 1680 scanned ports on server2.tecmint.com (192.168.0.101) are UNfiltered
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.382 seconds
You have new mail in /var/spool/mail/root

12. Scan a Host to check its protected by Firewall

To scan a host if it is protected by any packet filtering software or Firewalls.

[root@server1 ~]# nmap -PN 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:30 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.399 seconds

13. Find out Live hosts in a Network

With the help of “-sP” option we can simply check which hosts are live and up in Network, with this option nmap skips port detection and other things.

[root@server1 ~]# nmap -sP 192.168.0.*

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-18 11:01 EST
Host server1.tecmint.com (192.168.0.100) appears to be up.
Host server2.tecmint.com (192.168.0.101) appears to be up.
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)
Nmap finished: 256 IP addresses (2 hosts up) scanned in 5.109 seconds

14. Perform a Fast Scan

You can perform a fast scan with “-F” option to scans for the ports listed in the nmap-services files and leaves all other ports.

[root@server1 ~]# nmap -F 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:47 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1234 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.322 seconds

15. Find Nmap version

You can find out Nmap version you are running on your machine with “-V” option.

[root@server1 ~]# nmap -V

Nmap version 4.11 ( http://www.insecure.org/nmap/ )
You have new mail in /var/spool/mail/root

16. Scan Ports Consecutively

Use the “-r” flag to don’t randomize.

[root@server1 ~]# nmap -r 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 16:52 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.363 seconds

17. Print Host interfaces and Routes

You can find out host interface and route information with nmap by using “–iflist” option.

[root@server1 ~]# nmap --iflist

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 17:07 EST
************************INTERFACES************************
DEV  (SHORT) IP/MASK          TYPE     UP MAC
lo   (lo)    127.0.0.1/8      loopback up
eth0 (eth0)  192.168.0.100/24 ethernet up 08:00:27:11:C7:89

**************************ROUTES**************************
DST/MASK      DEV  GATEWAY
192.168.0.0/0 eth0
169.254.0.0/0 eth0

In above output, you can see that map is listing interfaces attached to your system and their respective routes.

18. Scan for specific Port

There are various options to discover ports on remote machine with Nmap. You can specify the port you want nmap to scan with “-p” option, by default nmap scans only TCP ports.

[root@server1 ~]# nmap -p 80 server2.tecmint.com

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 17:12 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
PORT   STATE SERVICE
80/tcp open  http
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) sca

19. Scan a TCP Port

You can also specify specific port types and numbers with nmap to scan.

[root@server1 ~]# nmap -p T:8888,80 server2.tecmint.com

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 17:15 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
PORT     STATE SERVICE
80/tcp   open  http
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.157 seconds

20. Scan a UDP Port

[root@server1 ~]# nmap -sU 53 server2.tecmint.com

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 17:15 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
PORT     STATE SERVICE
53/udp   open  http
8888/udp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.157 seconds

21. Scan Multiple Ports

You can also scan multiple ports using option “-p“.

[root@server1 ~]# nmap -p 80,443 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-18 10:56 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
PORT    STATE  SERVICE
80/tcp  open   http
443/tcp closed https
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.190 seconds

22. Scan Ports by Network Range

You can scan ports with ranges using expressions.

[root@server1 ~]#  nmap -p 80-160 192.168.0.101

23. Find Host Services version Numbers

We can find out service’s versions which are running on remote hosts with “-sV” option.

[root@server1 ~]# nmap -sV 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 17:48 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE VERSION
22/tcp   open  ssh     OpenSSH 4.3 (protocol 2.0)
80/tcp   open  http    Apache httpd 2.2.3 ((CentOS))
111/tcp  open  rpcbind  2 (rpc #100000)
957/tcp  open  status   1 (rpc #100024)
3306/tcp open  mysql   MySQL (unauthorized)
8888/tcp open  http    lighttpd 1.4.32
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 12.624 seconds

24. Scan remote hosts using TCP ACK (PA) and TCP Syn (PS)

Sometimes packet filtering firewalls blocks standard ICMP ping requests, in that case, we can use TCP ACK and TCP Syn methods to scan remote hosts.

[root@server1 ~]# nmap -PS 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 17:51 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.360 seconds
You have new mail in /var/spool/mail/root

25. Scan Remote host for specific ports with TCP ACK

[root@server1 ~]# nmap -PA -p 22,80 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 18:02 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
PORT   STATE SERVICE
22/tcp open  ssh
80/tcp open  http
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.166 seconds
You have new mail in /var/spool/mail/root

26. Scan Remote host for specific ports with TCP Syn

[root@server1 ~]# nmap -PS -p 22,80 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 18:08 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
PORT   STATE SERVICE
22/tcp open  ssh
80/tcp open  http
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.165 seconds
You have new mail in /var/spool/mail/root

27. Perform a stealthy Scan

[root@server1 ~]# nmap -sS 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 18:10 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.383 seconds
You have new mail in /var/spool/mail/root

28. Check most commonly used Ports with TCP Syn

[root@server1 ~]# nmap -sT 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 18:12 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
111/tcp  open  rpcbind
957/tcp  open  unknown
3306/tcp open  mysql
8888/tcp open  sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 0.406 seconds
You have new mail in /var/spool/mail/root

29. Perform a tcp null scan to fool a firewall

[root@server1 ~]# nmap -sN 192.168.0.101

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2013-11-11 19:01 EST
Interesting ports on server2.tecmint.com (192.168.0.101):
Not shown: 1674 closed ports
PORT     STATE         SERVICE
22/tcp   open|filtered ssh
80/tcp   open|filtered http
111/tcp  open|filtered rpcbind
957/tcp  open|filtered unknown
3306/tcp open|filtered mysql
8888/tcp open|filtered sun-answerbook
MAC Address: 08:00:27:D9:8E:D7 (Cadmus Computer Systems)

Nmap finished: 1 IP address (1 host up) scanned in 1.584 seconds
You have new mail in /var/spool/mail/root

Cacti Installation on Centos-6.5

Source :

> http://www.unixmen.com/install-cacti-network-monitoring-tool-on-centos-6-4-rhel-6-4-scientific-linux-6-4/

Cacti Installation
Nagios with Cacti through the NPC plugin on CentOS 6.3

------------------------------------------------------------------------------------------

[root@test html]# pwd
/var/www/html
[root@test html]# ll
total 4
lrwxrwxrwx 1 root root 12 Jan 10 12:56 cacti -> cacti-0.8.8b
drwxr-xr-x 13 1000 users 4096 Aug 7 2013 cacti-0.8.8b
[root@test html]#

--------------------------------------------------------------------------------------------

[root@server ~]# yum install httpd httpd-devel -y

yum install mysql mysql-server -y
yum install php-mysql php-pear php-common php-gd php-devel php php-mbstring php-cli php-mysql -y
yum install php-snmp -y
yum install net-snmp-utils net-snmp-libs php-pear-Net-SMTP -y
yum install rrdtool -y
[root@server ~]# /etc/init.d/httpd start
[root@server ~]# /etc/init.d/mysqld start
[root@server ~]# /etc/init.d/snmpd start
[root@server ~]# chkconfig httpd on
[root@server ~]# chkconfig mysqld on
[root@server ~]# chkconfig snmpd on
cd /var/www/html
wget http://www.cacti.net/downloads/cacti-0.8.8b.tar.gz
tar -xzvf cacti-0.8.8b.tar.gz
ln -s cacti-0.8.8b cacti
adduser cacti
echo "*/5 * * * * cacti php /var/www/html/cacti/poller.php &>/dev/null" >> /etc/cron.d/cacti
cd /var/www/html/cacti
chown -R cacti.apache rra log  

chmod 775 rra log
Permission Output : [root@test cacti]# ls -lrt
total 1088
-rw-r--r-- 1 cacti apache    353 Apr  4  2012 script_server.pl
drwxr-xr-x 5 cacti apache   4096 Apr  4  2012 resource
-rw-r--r-- 1 cacti apache     48 Apr  4  2012 README
drwxrwxr-x 2 cacti apache   4096 Apr  4  2012 log
-rw-r--r-- 1 cacti apache  15141 Apr  4  2012 LICENSE
 Database : [root@server ~]# mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 5.1.69 Source distribution

Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> create database cacti;
Query OK, 1 row affected (0.01 sec)

mysql> GRANT ALL ON cacti.* TO cacti@localhost IDENTIFIED BY 'centos';
Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)

mysql> exit
Bye
cd /var/www/html/cacti/include/
vi config.php

$database_type = "mysql";
$database_default = "cacti";
$database_hostname = "localhost";
$database_username = "cactiuser";
$database_password = "MyV3ryStr0ngPassword";
$database_port = "3306";
$database_ssl = false;
$url_path = "/cacti/";

==================================
Troublesoot on RHEL/CentOS 7.x
==================================

source : http://www.tecmint.com/install-cacti-network-monitoring-on-rhel-centos-6-3-5-8-and-fedora-17-12/

1) Validation error when adding cacti host to the graphs tree


Open host.php in line 179
vi /usr/share/cacti/host.php +179
Replace the line 179:
input_validate_input_number(get_request_var_post('drp_action'));
with
input_validate_input_regex(get_request_var_post('drp_action'), "^([a-zA-Z0-9_]+)$");
Restart Apache service:
service httpd restart
Open your Cacti, re-add your host to the desired graphs tree and voila! It should work now:)

2) graphs not showing up in cacti :

- wrong permissions 
The permissions for the rra and log folder is set to 755, cactiuser is owner. 

- crontab entry missing or wrong 
*/5 * * * * cactiuser php /usr/share/cacti/poller.php > /dev/null 2>&1 

- lack of disk storage 
No.