Restrict RADIUS usage in Server 5.x

This is a follow up post to my previous article about how to setup RADIUS on Server 5.x

In my Open Directory user list I have a user called scanner with a password of, you guessed it, scanner. Now I know this isn’t the most secure thing ever but the user only has very limited access. Recently I wanted to implement RADIUS so that the VPN concentrator could authenticate against Open Directory but I certainly don’t want the scanner user to be able to authenticate. Previously I would fire up WorkGroup Manager and build a service access control list, SACL. However with WGM now gone I have to do it on the command line. After some hacking I figured it out.

First, you’ll need to make a group in OD called VPN and put the users you would like to have VPN access in it. Then whip open a terminal and get the GUID of that group.

dscl localhost read /LDAPv3/127.0.0.1/Groups/VPN

You’re looking for the “GeneratedUID” record this somewhere. Next edit the following script and put your GeneratedUID into the line where it says NestedGroups


dscl localhost create /Local/Default/Groups/com.apple.access_radius
dscl localhost create /Local/Default/Groups/com.apple.access_radius RealName com.apple.access_radius
dscl localhost create /Local/Default/Groups/com.apple.access_radius passwd "*"
dscl localhost create /Local/Default/Groups/com.apple.access_radius gid 260
dscl localhost create /Local/Default/Groups/com.apple.access_radius NestedGroups PASTE_GUID_HERE


Then reboot radius with a serveradmin stop/start radius and you should be good to go!

Make certificates quickly

Now that you have your own Certificate Authority setup from my previous article you’ll want a fast way of whipping up new certs. Never fear for making certs is here. Drop the following code into an executable file and place it into the myCA folder. You’ll be able to make certificates at whim by issuing a command like

make-cert.sh hostname.lan.domain.com 3650 01


#!/bin/bash

mkdir $HOSTNAME
openssl genrsa -des3 -out $HOSTNAME/$HOSTNAME.key 4096
openssl req -new -key $HOSTNAME/$HOSTNAME.key -out $HOSTNAME/$HOSTNAME.csr
openssl x509 -req -days $DAYS -in $HOSTNAME/$HOSTNAME.csr -CA cert/cert.pem -CAkey key/ca.key.pem -set_serial $SERIAL -out $HOSTNAME/$HOSTNAME.crt
openssl rsa -in $HOSTNAME/$HOSTNAME.key -out $HOSTNAME/$HOSTNAME.key.insecure
mv $HOSTNAME/$HOSTNAME.key $HOSTNAME/$HOSTNAME.key.secure
mv $HOSTNAME/$HOSTNAME.key.insecure $HOSTNAME/$HOSTNAME.key
exit 0


RADIUS Setup for OS X El Capitan – Server 5.x

Quite simple to setup. First paste in the following commands.

radiusconfig -setconfig auth yes
radiusconfig -setconfig auth_badpass yes

Now install an SSL cert/key pair for your host, the built in ones are found in /etc/certificates or you followed my previous article about becoming a certificate authority and you have the certs on hand.

radiusconfig -installcerts /path/to/key /path/to/cert


Now… if you didn’t make your own CA and you’re using the built in Apple Server certs then you’ll have to do some extra magicary. First use pull an ls /etc/certificates and not the key, cert, and chain files for your host.


radiusconfig -installcerts /path/to/key.pem /path/to/cert.pem /path/to/chain.pem
radiusconfig -setcertpassword
Apple:UseCertAdmin


The last line is the ‘magic’ that I spoke of earlier.

Finally add some clients

radiusconfig -addclient other

Then start the radius server

serveradmin start radius


When I did this recently I didn’t have a way to test the server so I installed the FreeRadius server via brew.

brew install freeradius-server

And then tested the server by using radtest The binary can be found in the following directory /usr/local/Cellar/freeradius-server/3.0.9/bin

The syntax of the command is as follows:

radtest username password radius-server[:port] nas-port-number secret

Here’s an example:

radtest username password 192.168.1.1 10 secret


An Access-Accept is a passing grade!

Mac OS X Server 5.x El Capitan SSL Certificate Authority

I use Open Directory a lot, I can’t think of many times when I don’t use it at least once a day in some way whether that be direct or indirect. It’s not the best directory system out there – hell, it’s not even very good but it’s what the fine people at Apple have supplied us with and it’s what I use. Although I have long had a pet peeve with the way OD is built if you just run through the setup wizard. The certificate expires in one year. Almost every time I encounter an OD server in the wild nine times out of ten the certs are a mess. They’re either expired or about to expire and all the services that depend on them are freaking out. The clients are constantly being prompted to accept an invalid cert and OD fail-over tends to stop working. My solution has been to build a certificate authority for all my OD installs and to build my own certs that are valid for ten years, that way I won’t have to worry about them expiring and let’s be honest there’s no Mac server on the planet that’s going to last ten years lol (sense the cynicism yet?)

Create the Root Key

First we’re going to hop into a terminal on any Mac OS X box and navigate to somewhere safe in the file system and build the master key, make sure the password you use for this is kept secret and safe.

cd /some/where/safe/I/dont/care/where
mkdir -p myCA/cert myCA/key
cd myCA
openssl genrsa -aes256 -out key/ca.key.pem 4096
chmod 400 key/ca.key.pem


That OpenSSL command is going to ask you a bunch of questions, answer them to the best way you see fit and for the common name put the organization that you’re building this certificate authority for. Do not put an actual domain. Record what you wrote for Common Name because we’re going to need it later. Whitespaces are allowed. Oh and one more pro tip, make sure the value of the certificate common is unique and can’t be half-matched. For example I made a root cert called “Client Name” but when it came to do deploy the certificate via munki, the check install script found a cert called “Client Name Open Directory” and thus the command matched and wouldn’t deploy the new root cert.

Create the Root Cert


openssl req -key key/ca.key.pem -new -x509 -days 3650 -sha256 -extensions v3_ca -out cert/cert.pem
chmod 444 cert/cert.pem


Now we have two files.

cert/cert.pem – This is your CA’s certificate and can be publicly available and of course world readable. You will need to load this certificate into all the clients in your network.

key/ca.key.pem – This is your CA’s private key. Although it is protected with a passphrase you should restrict access to it, so that only root can read it.

Create the First Server key/cert combo

We can now start creating SSL certificates for our various servers and services. Create a directory named a hostname corresponding to the hostname for the computer or service you are creating the certificate for.

Create the first key

openssl genrsa -aes256 -out hostname/hostname.domainname.key 4096

While answering the questions for this make sure you type in the FQDN for server or service you want to secure into Common Name.

Create the server cert

openssl req -new -key hostname/hostname.domainname.key -out hostname/hostname.domainname.csr

Sign the cert

openssl x509 -req -days 3650 -in hostname/hostname.domainname.csr -CA cert/cert.pem -CAkey key/ca.key.pem -set_serial 01 -out hostname/hostname.domainname.crt

Now before we continue I have to drill into you that it’s imperative that you document these certs as you make them, which hosts they’re deployed on to, and what the serial number is. It will help you in the long run.

Finally we’re going to make a passwordless version of the server key, this is the key that we’ll ultimately use on our server. We need a passwordless key so that the Mac OS X services do not need human intervention when trying to use the certs. Otherwise you’ll have to type the cert password in every time you restart the service.


openssl rsa -in hostname/hostname.domainname.key -out hostname/hostname.domainname.key.insecure
mv hostname/hostname.domainname.key hostname/hostname.domainname.key.secure
mv hostname/hostname.domainname.key.insecure hostname/hostname.domainname.key


Import the CA and Cert

Copy the myCA/cert.pem, hostname/hostname.domainname.key, and hostname/hostname.domainname.crt files to your Mac OS X server. Double click on the myCA/cert.pem, this should open the file with Keychain Access which will ask you which keychain to import the cert to. Select the system keychain and then double click on the entry in Keychain Access and set the trust setting to Always Trust.

Next open Server.app and click on Certificates. Click on the gear menu and select Import Certificate Identity. Drag in the hostname/hostname.domainname.key, and hostname/hostname.domainname.crt files, when you do this you should see that the files are signed by the organization that you entered in step one. Finally select the cert from the list of certs in server.app and give it time to switch over.

Finally fire up the wiki service in server.app, whip open your browser of choice and connect to the FQDN that you create the SSL cert for. Remember, if your cert common name doesn’t match the way you address the wiki in the URL bar you will get a hostname mismatch error. You MUST make sure the names match from what you type into the certificate’s common name and how you connect to the wiki.

Root Cert Deployment

So now maybe you want to be able to use this cert with some of your clients right? You can do this a multitude of ways. Such as:

Copy the file to /tmp across your network and run the following command as root


security add-trusted-cert -d -r trustRoot -k "/Library/Keychains/System.keychain" "/tmp/cert.pem"; srm "/tmp/cert.pem"


Or if you’re cool you’ll use some sort of package deployment system. I use munki because it’s not backed by some money hungry corporation. Here’s looking at you Cohen. 😉 To do this I made a new package with Composer dropped my root cert into /tmp and then wrapped then finished the Composer wizard. Import this package into munki using munkiimport and then drop aforementioned command into post-install script.

For extra bonus points it would be cool to see if the root cert is installed before we go pushing this package to all the workstations in the network. To do this I added a little check install script to munki. Note that you have change the -c flag to match whatever you wrote for the root cert common name way back in step one.


#!/bin/bash

if [ $? != 0 ]; then
exit 0
else
exit 1
fi


You’ll note that the exit codes are reversed here, it’s because Munki will only install if the check install script exits on 0 which is how our security check command will exit if it finds the cert installed. So we flip the exit code to make munki do our bidding.

At this point you should be feeling like a rock star for the following reasons:

• You haven’t given Go Daddy any money
• You’ve successfully built and deployed your own cert authority
• You won’t have to worry about onboarding new machines with the cert cause you’ve got in munki

Migrate DNS from Snow Leopard Server to OS X Server 5.x

I was faced with a DNS migration, but from Snow Leopard Server to Server.app 5.x. There were only 9 zones but there are hundreds of records and Apple provides zero tools to help make this migration easy. But, I found a hack. Now I’m going to say right now that I just found that this worked and YMMV.

First, on your Snow Leopard Server box do an ls /var/named/zones and make a primary zone in Server.app 5.x for every file listed in this directory. Then tarball up all these files and copy them over to your Server.app 5.x machine. One by copy the zones files from this tarball into /Library/Server/named matching the names as you go with some tab-auto-complete action.

For example, if the zone files in your Snow Leopard server are:


db.1.5.10.in-addr.arpa.zone.apple
db.mgmt.clientname.com.zone.apple
db.remote.clientname.com.zone.apple
db.backup.clientname.com.zone.apple
db.lan.clientname.com.zone.apple


Then you would issue the following commands:


sudo cp db.1.5.10.in-addr.arpa.zone.apple /Library/Server/named/db.1.5.10.in-addr.arpa
sudo cp db.lan.clientname.com.zone.apple /Library/Server/named/db.lan.clientname.com
sudo cp db.mgmt.clientname.com.zone.apple /Library/Server/named/db.mgmt.clientname.com
sudo cp db.remote.clientname.com.zone.apple /Library/Server/named/db.remote.clientname.com
sudo cp db.backup.clientname.com.zone.apple /Library/Server/named/db.backup.clientname.com


Recovering Apple’s Wiki After Storage Failure or How I Learned to Love pg_resetxlog

Recently I received a panicked phone call from a fellow sysadmin who was in a real jam. He had a customer who was dumping all their knowledge into Apple’s Wiki system running on top of Mountain Lion and Server 2.2.5. The storage system in the mini failed and they had to recover from backup, however the backup was setup using Carbon Copy Cloner and as we all know you cannot rely on a file-based backup system to backup a running postgres database.

After the data was restored the machine did boot but all the postgres services would not start, including the wiki. After reviewing the logs for quite some time I found some entries of pgstat wait timeout and then no log entries for about a day. I assumed that this was our hard drive failure window. Then two days later the log started producing tons of postgres crash statements, launchctl statements and this little nugget Jan 19th 13:29 database system was interrupted This was all the information I needed. From what I can tell, between the time that Carbon Copy Cloner calculated changes and the time that it copied the data some minute things changed within the database and so CCC didn’t get a proper clone. It appears that this error is caused when the database engine no longer knows where to start writing data back into the database. Basically, the counters were broken and had to be reset. Luckily postgres makes a tool called pg_resetxlog

The command has this basic structure:

pg_resetxlog
-x XID set next transaction ID
-m XID set next multitransaction ID
-o OID set next OID
-l TLI,FILE,SEG force minimum WAL starting location for new transaction log
/path/to/database/directory


Now the Apple Wiki postgres data is held within /Library/Server/PostgreSQL\ For\ Server\ Services/Data which is an important detail to hold onto. Within this directory are all the bits of info you’ll need to run the following calculations. You’ll also need this decimal to hex converter.

Source: http://www.postgresql.org/docs/9.0/static/app-pgresetxlog.html

A safe value for the next transaction ID (-x) can be determined by looking for the numerically largest file name in the directory pg_clog under the aforementioned postgres data directory, adding one, and then multiplying by 1048576. Note that the file names are in hexadecimal. It is usually easiest to specify the switch value in hexadecimal too. For example, if 0011 is the largest entry in pg_clog, -x 0x1200000 will work (five trailing zeroes provide the proper multiplier).

A safe value for the next multitransaction ID (-m) can be determined by looking for the numerically largest file name in the directory pg_multixact/offsets under the data directory, adding one, and then multiplying by 65536. As above, the file names are in hexadecimal, so the easiest way to do this is to specify the switch value in hexadecimal and add four zeroes.

A safe value for the next multitransaction offset (-O) can be determined by looking for the numerically largest file name in the directory pg_multixact/members under the data directory, adding one, and then multiplying by 65536. As above, the file names are in hexadecimal, so the easiest way to do this is to specify the switch value in hexadecimal and add four zeroes.

The WAL starting address (-l) should be larger than any WAL segment file name currently existing in the directory pg_xlog under the data directory. These names are also in hexadecimal and have three parts. The first part is the “timeline ID” and should usually be kept the same. Do not choose a value larger than 255 (0xFF) for the third part; instead increment the second part and reset the third part to 0. For example, if 00000001000000320000004A is the largest entry in pg_xlog, -l 0x1,0x32,0x4B will work; but if the largest entry is 000000010000003A000000FF, choose -l 0x1,0x3B,0x0 or more.

Once you have these four values you’re ready to try it out on your database. But before I began I requested a full bootable clone of the server as it was when they restored it, then I took this cloned and placed it into a VM in Fusion and snapped the VM before trying anything. Also, don’t forget that when you want to issue commands to the Apple postgres service you have to use the full path to the commands as well as use the _postgres user. My final command, which recovered the wiki system AND profile manager, looked like this:

sudo -u _postgres /Applications/Server.app/Contents/ServerRoot/usr/bin/pg_resetxlog -f -x 0x100000 -m 0x10000 -o 0x10000 -l 0x1,0x2,0x18 /Library/Server/PostgreSQL\ For\ Server\ Services/Data

Feel free to reach out if you are having issues.