Tiny Deathstars of Foulness

Prepare for your network administrators to cringe… I’ve spoken on these commands but never really put them together in this way, exactly. So I wanted to find a coworker on a network. So one way to find people is to use a ping sweep. Here I’m going to royally piss off my switch admins and ping sweep the subnet:


Next, I’m going to run arp to translate:

arp -a

Finally, if a machine is ipv6, it wouldn’t show up. So I’m going to run:

ndp -a

Now, I find the hostname, then look at the MAC address, copy that to my clipboard, find for that to get the IP and then I can flood that host with all the things. Or you could use nmap… :-/

January 7th, 2017

Posted In: Mac OS X, Network Infrastructure

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DHCP, or Dynamic Host Control Protocol, is the service used to hand out IP addresses and other network settings by network appliances and servers. The DHCP Server built into OS X Server 3, installed on Yosemite running the Server app (aka Yosemite frickin’ server) is easy-to-use and fast. It’s pretty transparent, just as DHCP services should be. To install the service, open the Server app and then click on the Show button beside Advanced in the server sidebar. Then click on DHCP.


At the DHCP screen, you’ll see two tabs: Settings, used for managing the service and Clients, used to see DHCP leases in use by computers that obtain IP address information from the server. You’ll also see an ON and OFF switch, but we’re going to configure our scopes, or Networks as they appear in the Server app, before we enable the service. To configure a scope, double-click on the first entry in the Networks list.


Each scope, or Network, will have the following options:

  • Name: A name for the scope, used only on the server to keep track of things.
  • Lease Duration: Select an hour, a day, a week or 30 days. This is how long a lease that is provided to a client is valid before the lease expires and the client must find a new lease, either from the server you’re configuring or a different host.
  • Network Interface: The network interface you’d like to share IPs over. Keep in mind that you can tag multiple VLANs on a NIC, assign each an interface in OS X and therefore provide different scopes for different VLANs with the same physical computer and NIC.
  • Starting IP Address: The first IP address used. For example, if you configure a scope to go from to you would have 50 useable IP addresses.
  • Ending IP Address: The last IP address used in a scope.
  • Subnet Mask: The subnet mask used for the client configuration. This setting determines the size of the network.
  • Router: The default gateway, or router for the network. Often a .1 address for the subnet used in the Starting and Ending IP address fields. Note that while in DHCP you don’t actually have to use a gateway, OS X Server does force you to do so or you cannot save changes to each scope.
  • DNS: Use the Edit button for DNS to bring up a screen that allows you to configure the DNS settings provided as part of each DHCP scope you create, taking note that by default you will be handing out a server of if you don’t configure this setting.

The DNS settings in the DHCP scope are really just the IP addresses to use for the DNS servers and the search domain. The search domain is the domain name appended to all otherwise incomplete Fully Qualified Domain Names. For example, if we use internal.krypted.lan and we have a DNS record for wiki.internal.krypted.lan then we could just type wiki into Safari to bring up the wiki server. Click the minus sign button to remove any data in these fields and then click on the plus sign to enter new values.


Click OK to save DNS settings and then OK to save each scope. Once you’ve build all required scopes, start the service. Once started, verify that a new client on the network gets an IP. Also, make sure that there are no overlapping scopes and that if you are moving a scope from one device to another (e.g. the server you’re setting up right now) that you renew all leases on client systems, most easily done using a quick reboot, or using “ipconfig /release” on a Windows computer. If you have problems with leases not renewing in OS X, check out this article I did awhile back.

So far, totally easy. Each time you make a change, the change updates a few different things. First, it updates the /etc/bootpd.plist property list, which looks something like this (note the correlation between these keys and the settings in the above screen shots.:






192.168.210 Wi-Fi










Settings from this file include:

  • dhcp_enabled – Used to enable dhcp for each network interface. Replace the immediately below with en0 . For additional entries, duplice the string line and enter each from ifconfig that you’d like to use dhcp on.
  • bootp_enabled – This can be left as Disabled or set to an array of the adapters that should be enabled if you wish to use the bootp protocol in addition to dhcp. Note that the server can do both bootp and dhcp simultaneously.
  • allocate – Use the allocate key for each subnet in the Subnets array to enable each subnet once the service is enabled.
  • Subnets – Use this array to create additional scopes or subnets that you will be serving up DHCP for. To do so, copy the entry in the array and paste it immediately below the existing entry. The entry is a dictionary so copy all of the data between and including the and immediately after the entry for the subnet itself.
  • lease_max and lease_min – Set these integers to the time for a client to retain its dhcp lease
  • name – If there are multiple subnet entries, this should be unique and reference a friendly name for the subnet itself.
  • net_address – The first octets of the subnet followed by a 0. For example, assuming a /24 and 172.16.25 as the first three octets the entry would be
  • net_mask – The subnet mask clients should have
  • net_range – The first entry should have the first IP in the range and the last should have the last IP in the range. For example, in the following example the addressing is to
  • dhcp_domain_name_server – There should be a string for each DNS server supplied by dhcp in this array
  • dhcp_domain_search – Each domain in the domain search field should be suppled in a string within this array, if one is needed. If not, feel free to delete the key and the array if this isn’t needed.
  • dhcp_router – This entry should contain the router or default gateway used for clients on the subnet, if there is one. If not, you can delete the key and following string entries.

If you run the serveradmin command, followed by the settings verb and then the dhcp service, you’ll see the other place that gets updated:

serveradmin settings dhcp

The output indicates that:

dhcp:static_maps = _empty_array
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:WINS_secondary_server = ""
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:selected_port_name = "en0"
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:dhcp_router = ""
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:dhcp_domain_name_server:_array_index:0 = ""
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:net_mask = ""
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:WINS_NBDD_server = ""
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:net_range_start = ""
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:lease_max = 3600
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:dhcp_domain_search:_array_index:0 = "internal.krypted.lan"
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:descriptive_name = "192.168.210 Wi-Fi"
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:WINS_primary_server = ""
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:net_range_end = ""
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:dhcp_ldap_url = _empty_array
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:WINS_node_type = "NOT_SET"
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:net_address = ""
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:dhcp_enabled = yes
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:dhcp_domain_name = "internal.krypted.lan"
dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:WINS_scope_id = ""
dhcp:subnet_defaults:logVerbosity = "MEDIUM"
dhcp:subnet_defaults:WINS_node_type_list:_array_index:0 = "BROADCAST_B_NODE"
dhcp:subnet_defaults:WINS_node_type_list:_array_index:1 = "HYBRID_H_NODE"
dhcp:subnet_defaults:WINS_node_type_list:_array_index:2 = "NOT_SET"
dhcp:subnet_defaults:WINS_node_type_list:_array_index:3 = "PEER_P_NODE"
dhcp:subnet_defaults:WINS_node_type_list:_array_index:4 = "MIXED_M_NODE"
dhcp:subnet_defaults:dhcp_domain_name = ""
dhcp:subnet_defaults:WINS_node_type = "NOT_SET"
dhcp:subnet_defaults:routers = _empty_dictionary
dhcp:subnet_defaults:logVerbosityList:_array_index:0 = "LOW"
dhcp:subnet_defaults:logVerbosityList:_array_index:1 = "MEDIUM"
dhcp:subnet_defaults:logVerbosityList:_array_index:2 = "HIGH"
dhcp:subnet_defaults:dhcp_domain_name_server:_array_index:0 = ""
dhcp:subnet_defaults:selected_port_key = "en0"
dhcp:subnet_defaults:selected_port_key_list:_array_index:0 = "bridge0"
dhcp:subnet_defaults:selected_port_key_list:_array_index:1 = "en0"
dhcp:subnet_defaults:selected_port_key_list:_array_index:2 = "p2p0"
dhcp:subnet_defaults:selected_port_key_list:_array_index:3 = "en1"
dhcp:logging_level = "MEDIUM"

Notice the correlation between the uuid string in /etc/bootp.plist and the arrayid entry for each subnet/network/scope (too many terms referring to the same thing, ahhhh!). Using the serveradmin command you can configure a lot more than you can configure in the Server app gui. For example, on a dedicated DHCP server, you could increase logging level to HIGH (as root/with sudo of course):

serveradmin settings dhcp:logging_level = "MEDIUM"

You can also change settings within a scope. For example, if you realized that you were already using and 201 for statically assigned IPs elsewhere you can go ahead and ssh into the server and change the first IP in a scope to 202 using the following (assuming the uuid of the domain is the same as in the previous examples):

serveradmin settings dhcp:subnets:_array_id:B03BAE3C-AB79-4108-9E5E-F0ABAF32179E:net_range_start = ""

You can also obtain some really helpful information using the fullstatus verb with serveradmin:

serveradmin fullstatus dhcp

This output includes the number of active leases, path to log file (tailing that file is helpful when troubleshooting issues), static mappings (configured using the command line if needed), etc.

dhcp:state = "RUNNING"
dhcp:backendVersion = "10.5"
dhcp:timeOfModification = "2014-10-04 04:24:17 +0000"
dhcp:numDHCPActiveClients = 0
dhcp:timeOfSnapShot = "2014-10-04 04:24:19 +0000"
dhcp:dhcpLeasesArray = _empty_array
dhcp:logPaths:systemLog = "/var/log/system.log"
dhcp:numConfiguredStaticMaps = 1
dhcp:timeServiceStarted = "2014-10-04 04:24:17 +0000"
dhcp:setStateVersion = 1
dhcp:numDHCPLeases = 21
dhcp:readWriteSettingsVersion = 1

Once started, configure reservations using  the /etc/bootptab file. This file should have a column for the name of a computer, the hardware type (1), the hwaddr (the MAC address) and ipaddr for the desired IP address of each entry:

# hostname hwtype hwaddr ipaddr bootfile
a.krypted.lan 1 00:00:00:aa:bb:cc
b.krypted.lan 1 00:00:00:aa:bb:cc

You can start and stop the service either using the serveradmin command:

serveradmin stop dhcp
serveradmin start dhcp

Or using the launchctl:

sudo /bin/launchctl unload -w /System/Library/LaunchDaemons/bootps.plist
sudo ; /bin/launchctl load -w /System/Library/LaunchDaemons/bootps.plist

On the clients, you can then use ifconfig followed by the getpacket verb and then an interface connected to the same network as the DHCP server in order to see the information supplied by the dhcp service, including the system that provided the DHCP lease to the client computers.

October 16th, 2014

Posted In: Mac OS X, Mac OS X Server, Mac Security, Mass Deployment, Network Infrastructure

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HomeGroup is a new home security feature of WIndows 7. HomeGroup resemble how you protect your home (an analogy I use in the Mac OS X Security book as well): Keep the outside doors locked and keep the interior doors unlocked (unless you’re on the crapper). HomeGroup can be initiated by any Windows 7 version other than Home Basic and Starter editions. Any Windows 7 machine can join a HomeGroup though and it is not a backwards compatible feature, meaning that if you’re still running Windows 95, 98 or Millineum don’t bother to upgrade (you probably can’t read this site anyway). But 2K to Vista, you gots’ta upgrade to play (not that this one feature is worth the upgrade).

Provided all the computers that will be in your inner ring are running Windows 7, the new HomeGroup feature of Windows 7 allows you to share specified resources with others who join the HomeGroup by having each join using a password – a password that is different from the one to join the wireless network. Guests can access the network for Internet, or other untrusted access, without being given the password to join the HomeGroup. I’m not sold that anyone will allow guests to access the Internet in this fashion but I can see scenarios where it could happen (do people still have LAN Party’s).

To setup a HomeGroup, click on the HomeGroup link at the bottom of the Network and Sharing Center. Then, click on the Create a HomeGroup button, selecting which Libraries to share to the inner circle (HomeGroup) by checking or unchecking the boxes. Click on Next to create the HomeGroup and distribute the provided password, or reset it in the Network and Sharing Center. Next, from each client, join the HomeGroup and then click on HomeGroup and then sharing options to control which resources to share from your computer.

Now about the crapper comment from earlier, you can specifically exclude files in the inner ring as well. So if you’ve shared out a resource you do have the ability to get a little more granular with your controls. It’s not 802.1x, but for a little home tinkering security whatnot, it’s not half bad… File sharing still works pretty much the same, which means you can do almost all of this without using the “HomeGroup” feature, but it does make it a little easier for those new to sharing resources!

October 22nd, 2009

Posted In: Windows XP

Tags: , , , , , is a nice site that allows you to test the speed of your Internet connection for free. They also have a free companion iPhone app that allows you to test the speed of an Internet connection without actually opening up your laptop.

October 21st, 2009

Posted In: iPhone, Network Infrastructure

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