Today I had some problems running ISA 2004 en IAS on the same server. At the beginning the customer was running ISA 2000 and IAS on the same server without any problems. By incident, the customer was forced to upgrade his ISA. They had a 2004 license, so ISA 2004 it was.
I noticed that ISA 2004 puts a “Default ISA policy” with the highest priority in the remote access policies. The rule blocks all RADIUS requests, so I had to manually remove the access policy. After the removal everything was working fine again.
I had to change the configuration in the ISA server again and the “Default ISA policy” came back in IAS. So I had to delete the rule again. I also tried to change the priority of the rule, but the “Default ISA policy” gets the highest priority again after applying a change in ISA.
I cannot find anything specific about this problem on the internet, so maybe someone experienced this before and can provide me with an answer to disable this behavior.
Microsoft IAS server is often used as RADIUS server to authenticate VPN users or in conjunction with ISA reverse proxy to authenticate OWA users or PDA synchronization.
Today I had to install an ISA reverse proxy server with ISA 2006 Standard and Exchange 2007. I wanted to install Microsoft IAS as RADIUS server to authenticate the OWA users. Normally I install IAS on one, but preferably, on two domain controllers. I logged in on a domain controller through RDP. I noticed that the OS of the domain controller was Windows Server 2008.
Cool, finally working with a Windows Server 2008. After getting familiarized with the new view and layout, I started to search for a way to add the needed Windows component IAS. After searching for a while I found how to add Windows component. Looking at the complete list, I couldn’t find the Internet Authentication Service.
Oops, did Microsoft remove the IAS functionality from its server platform??? After googling for a second, I found that IAS has been replaced by Network Policy and Access Server service in Windows 2008.
Microsoft TechNet told me the following:
Network Policy Server (NPS) is the Microsoft implementation of a Remote Authentication Dial-in User Service (RADIUS) server and proxy in Windows Server 2008. NPS is the replacement for Internet Authentication Service (IAS) in Windows Server 2003.
As a RADIUS server, NPS performs centralized connection authentication, authorization, and accounting for many types of network access, including wireless and virtual private network (VPN) connections. As a RADIUS proxy, NPS forwards authentication and accounting messages to other RADIUS servers. NPS also acts as a health evaluation server for Network Access Protection (NAP). Source
After installing NPS, I started the configuration. You really have to get familiar with the way Windows Server 2008 works. There are a lot of different wizard and multiple configuration options to choose from. Everything looks a bit more fancy. NPS is not only a replacement for IAS, but has also many enhancements.
More information about installing and configuration Network Policy Server can be found in the article Understanding the new Windows Server 2008 Network Policy Server on WindowsNetworking.com. Here you can read that NPS has a lot of functions related to Network Access Protocol (NAP). A very detailed example of using NPS to perform NAP can be found in Brian Posey’s series An Introduction to Network Access Protoction.
Finally I had a day “off” and could test MAC Authentication Bypass (MAB) in our test environment at the office. I created the following test environment:
There are 4 different VLAN’s and a Cisco Catalyst 3750 connects the VLAN’s to each other. I wanted to create an environment with the following properties:
I have configured the necessary components and got the environment working with the above properties. The next few sections cover the configuration of the different components.
Cisco Catalyst 3750
Most of the configuration is done on the Cisco Catalyst 3750 switch. First of all I created the different VLAN’s on layer 2 of the OSI model. Next I created the SVI’s to make the VLANs routable. I used the standard SVI configuration. I used the ‘quick-and-dirty’ solution for configuring Wake On LAN (WOL) by just adding the ip directed-broadcast command to the SVI’s. The snippet below shows the SVI configuration.
ip address 192.168.1.254 255.255.255.0
ip address 192.168.10.254 255.255.255.0
ip address 192.168.15.254 255.255.255.0
ip address 192.168.30.254 255.255.255.0
The next step is configuring AAA and the RADIUS group for authenticating the connected clients to the network. The snippet shows these configuration.
aaa authentication dot1x default group radius
aaa authorization network default group radius
radius-server host 192.168.10.30 auth-port 1812 acct-port 1813 key ictivity
The following step is to enable 802.1x globally in the switch. You should use the command in the following snippet to enable 802.1x.
The last configuration snipper shows the configuration of a switch port. This switch port is configured use MAC Authentication Bypass as backup authentication method if 802.1x cannot authenticate.
switchport mode access
switchport voice vlan 15
dot1x pae authenticator
dot1x port-control auto
dot1x control-direction in
dot1x timeout tx-period 1
dot1x max-reauth-req 1
dot1x guest-vlan 30
spanning-tree bpduguard enable
I configured Internet Authentication Services on a Windows 2003 server. I didn’t configure the Active Directory, but use the local users and local groups to authenticate. I configured the RADIUS client inside IAS and started to create a Remote Access Policy. The Remote Access Policy matches a newly created Windows Group. The important aspects of the Policy are the Authentication options and the Advanced Attributes. The configuration of both is shown below.
The last step in the whole process is configuring the Windows Group and adding users to that group. The MAC address of the workstation is acting as username and password. Important to notice is that all characters are case-sensitive and the username and password should only contain lowercase characters. An example of username and password is: 0016762eccda.
After configuring the test environment I have done some testing. First was trying to connect a workstation and authenticate. This is working perfectly, you will see a nice IAS event message on the Windows 2003 server. Next I connected an IP Phone with a build-in switch and connected the workstation to the IP Phone. The workstation again authenticates flawlessly against the RADIUS server. The last test was trying to wake up the workstation via Wake On LAN. When you should down the workstation, the switch ports first goes in shutdown and re-enables after the complete shutdown of the workstation. Next the switch ports returns to Vlan 1 (switchport access vlan 1). I send the Magic Packet to the broadcast address of VLAN 1. The workstation starts booting and authenticates against the RADIUS server.
I can only say, that MAC Authentication Bypass is working perfectly in my TEST environment. Shortly I will try to implement it on the network of one of our customers, because he wants a cheap method for securing his switch ports.
I know, and I told the customer, that MAC authentication isn’t a very powerful tool for security the switch port. Because spoofing a valid MAC address is enough to get access to the network. But MAC authentication is still better, then no authentication at all. And let’s face it, what are the costs: NOTHING!!!
Most companies have a Windows 2003 server where IAS can be installed or you can use FreeRADIUS, so no costs on the OS. I have tried an IP Base and an IP Services IOS on the Cisco Catalyst 3750, both are working perfectly. A switch has minimal an IP Base image, so no additional costs here. The only costs are made during the configuration and testing of the authentication.
Check the latest article about MAB and MDA in an IP Phone environment
I am sure that many of you would like to do the same thing and many of you successfully configured it. I am trying to configure RADIUS Authentication on my Cisco 877W. I have two different RADIUS policies, the first for privilege level 1 and the second for privilege level 15. I am using Microsoft IAS as RADIUS server.
I configured two policies and the second policy has the following Advanced Options set.
This means that the user should get privilege level 15, when logging in. I configured the following on the Cisco877W router.
aaa authentication login AD group radius local none
aaa authorization exec AD group radius
radius-server host 10.10.1.1 auth-port 1812 acct-port 1813 key 7 KEY
radius-server retry method reorder
radius-server transaction max-tries 2
radius-server timeout 4
radius-server deadtime 2
radius-server vsa send authentication
line vty 0 4
access-class 10 in
exec-timeout 5 0
login authentication AD
transport preferred none
transport input ssh
transport output telnet ssh
The user doesn’t get the privilege level 15, but comes in privilege level 1 and has to enter enable to get into privilege level 15. I turned on RADIUS debugging and I see the shell code coming by, as the debug output below shows.
%SSH-5-SSH2_SESSION: SSH2 Session request from 10.10.1.103 (tty = 1)
using crypto cipher ‘aes256-cbc’, hmac ‘hmac-sha1’ Succeeded
RADIUS/ENCODE(00000716): ask “Password: ”
RADIUS/ENCODE(00000716): send packet; GET_PASSWORD
RADIUS/ENCODE(00000716):Orig. component type = EXEC
RADIUS/ENCODE(00000716): dropping service type,
“radius-server attribute 6 on-for-login-auth” is off
RADIUS(00000716): Config NAS IP: 0.0.0.0
RADIUS/ENCODE(00000716): acct_session_id: 1814
RADIUS/ENCODE: Best Local IP-Address 10.10.1.1 for Radius-Server 10.10.1.5
RADIUS(00000716): Send Access-Request to 10.10.1.5:1812 id 1645/31, len 81
RADIUS: authenticator 72 D9 B5 F1 76 72 9A D1 – 73 D7 E8 AF 21 F3 B5 0F
RADIUS: User-Name  6 “rene”
RADIUS: User-Password  18 *
RADIUS: NAS-Port  6 3
RADIUS: NAS-Port-Id  6 “tty3”
RADIUS: NAS-Port-Type  6 Virtual 
RADIUS: Calling-Station-Id  13 “10.10.1.103”
RADIUS: NAS-IP-Address  6 10.10.1.1
RADIUS: Received from id 1645/31 10.10.1.5:1812, Access-Accept, len 83
RADIUS: authenticator BB BF B5 FD 1D 36 67 9B – FE 5A EE 5A 6C 42 5E B9
RADIUS: Vendor, Cisco  25
RADIUS: Cisco AVpair 
RADIUS: Service-Type 
6 Login 
RADIUS: Class  32
RADIUS: 3C 09 04 AE 00 00 01 37
00 01 0A 0A 01 05 01 C8 [< ??????7????????]
RADIUS: A6 C0 C2 0D FD 4C 00
00 00 00 00 00 00 13 [?????L????????]
RADIUS(00000716): Received from id 1645/31
%SEC_LOGIN-5-LOGIN_SUCCESS: Login Success
[user: rene] [Source: 10.10.1.103] [localport: 22]
I am running out of options. I have tried to use the Cisco-AVpair in IAS, but no success. I tried using only Telnet, but no success. Maybe someone has an option to try…