Commonly Using Port Numbers

Port	TCP	UDP	Description
20	x		FTP-Data
21	x		FTP (login access)
22	x	x	SSH
23	x		Telent
25	x		SMTP (Mail, MTA)
49	x		TACACS+
53	x	x	DNS
69		x	TFTP
80	x	x	HTTP (Web)
110	x	x	POP3 (email); generally uses TCP)
119	x		NNTP (Usenet News)
123		x	NTP
139	x	x	NetBIOS (Microsoft)
143	x	x	IMAP
161	x	x	SNMP (Network Monitor)
179	x		BGP
443	x	x	HTTPS
465	x		SMTPS (Secure Mail over SSL)
993	x	x	IMAP (Secure IMAP over SSL)
995	x	x	POP3S (Secure POP3 over SSL)
1645,1812		x	RADIUS Authentication
1646,1813		x	RADIUS Accounting

Installing Active directory in Windows Server 2008

Before starting installation process, make sure that the IP address computer name are correct. Now use server manager to add rolls or type “oobe” in the command prompt. Now the following window will appear:

Press add roles and now press next

Select the Active directory Domain Services check box and press next . This tells the server we want to install active directory

Press next

press next

press install

now we may close this wizard, if we close we need to type “dcpromo” on the command prompt and continue installation. Otherwise, press the link in the window highlighted by blue

Note : all the above steps can be done just typing “dcpromo” in the command prompt.

We are using normal mode. So press next. Advanced mode installation can be used to install read only domain controller

Press next if we are not using NT4 computers

Now Select “Create a new domain in a new forest” because we are creating new domain. If we have existing domain and we want to add additional domain controller, add child domain etc. we must use the other option

Enter the domain name for our new domain

Enter the forest functional level. If forest functional level /domain functional level is higher, more features will be enabled. I will explain about forest and domain functional level in another post.

Enter the domain functional level. As above, higher is better

Select DNS because we don’t have another DNS server. If we have another one, we can use that one.

Note: If static IP not given already, it will give the warning. We can also give the IP address here. if error occurs again, that means you didn’t given IPv6 address. To solve this problem, either give IPv6 address or disable IPv6 addressing by removing check mark  in the configuration window of Network card

Press yes and next

Press next if we don’t want to change the location of active directory files. NTDS is the active directory database

Give the password to restore active directory if any problem occurs and press next

This window gives the summary of the answer we already given. If we want, we can press the export button to save the answer file for future installation or command line installation

Now active directory installation starts and tick the check box reboot on completion

After that reboot, we can see the role is installed in server manager. Also check the computer properties for details

Upgrading Windows Server 2003 to Windows Server 2008

Before joining/upgrading  the Windows Server 2003 to Windows server 2008 domain, we need to upgrade the schema. To check the scheme is in old version or not, do the following:

Open windows registry by type regedit on the command prompt and go to

Hkey_local_machine > system > current control set > services > ntds> schema version

now check the version :

• 31 means old
• 44 means new (windows server 2008)

If it is 31, it means we need to upgrade the schema. To upgrade the schema and make it ready for windows server 2008, do the following:

In the Windows Server 2008 DVD, go to sources > adprep directory and do the following commands

d:\souces\adprep> adprep /forestprep

d:\souces\adprep> adprep /domainprep /gpprep

notes:

• here My dvd drive is D:
• /gpprep : used to changes permissions on group policy objects

Now, we can join the server to Windows Server 2008 domain or if it is already a domain controller, we can upgrade it to Windows Server 2008

Installing and configuring SecureCRT for gns3

Secure CRT Installation

1. Download secureCRT with crack from internet (There are plenty of places, use google to search “SecureCRT with crack downlaod”)
2. Install secureCRT
3. copy the crack to installation directory (eg: C:\Program Files\VanDyke Software\SecureCRT\)
4. Run the crack as administrator (Right click the crack and in the menu select run as administrator)
5. Enter anything in name and company field and press generate. Now, the serials and other information appears.
6. Press the patch button to patch the secureCRT.exe file. That’s it.  Now the secure CRT installed correctly.

GNS3 configuration of secure CRT

1. Download and install GNS3, add IOS etc.
2. Go to Edit > Preferences > General > Terminal settings tab > SecureCRT > Change preconfigured terminal commands to SecureCRT (64 bit or 32 bit depending upon the version installed) > Press “use” button > press ok
3. Now add some routers (with IOS added) to work space and turn it on.
4. Press the console button to see the tabbed windows for each router

Note: if any error occurs, check the installation path of SecureCRT in the terminal command

Can’t authorize DHCP server (solution)

If you can’t authorize the DHCP server which is installed on a member server, login as enterprise administrator and try it.

how to login as enterprise administrator from member server

If you are simply login as administrator with password, it will be the administrator account in the member server. So use the fully qualified name to login as enterprise administrator like administrator@home.internal

Find the installation date of an OS

Go to command prompt and run the following command:
systeminfo | find /i "install date"

How to see and change default MTU in Windows

Open command prompt and type:

netsh interface ipv4 show subinterfaces

and hit Enter. We will get a list of all your network adapters installed on your PC. The MTU value is listed on the left



In command prompt, type the following to ping with an MTU size

ping google.com -f -l 1472

The -f marks packets that should not be fragmented in the ping. -l 1472 sets the size of the packet.



If we get successful replies, then your current MTU is fine for your connection. If we receive error messages like in the above image, then your packets are getting fragmented.

Try to find out successful value. When you find a successful value, you can then set a new MTU limit with this value.You will need to add IP/ICMP overheads (usually 28), so if 1462 is successful, then 1490 is your MTU limit.

To set new limit, in a command prompt use the following command:

netsh interface ipv4 set subinterface "Realtek" mtu=1490 store=persistent