A decker would simply slave important devices to his deck and use his deck's Firewall rating (plus any running programs) to defend his team from Matrix attack, but a Technomancer's living persona specifically cannot be a master or slave. Should the whole team just get the best commlinks they can afford and protect their own devices, or can the Technomancer bring his persona to bear against Matrix attacks against his team even if he hasn't already spotted and marked an incoming threat?
A lot of people think that the rule that technomancers can't slave devices is a little weird. But technomancers do interact with the matrix in a different way. And, because it's different, you have to figure out a different solution to the problem.
One solution to this problem is to always be running in the Matrix and making Matrix perception tests to check for problems on your team's devices. Another is to thread a machine sprite, stick it in a commlink, slave everyone to your sprited commlink, and then have it warn you when someone's trying to hack into your devices.
The matrix source book (Data Trails) is now out for 5th edition, and no new or better options have been given to technomancers. You can take my suggestions or just have your group house-rule that technomancers can slave devices.
There are several ways for a Technomancer to protect his team's gear.
- The TM could get a good commlink, slave all of the team's devices to it, then use the Infusion of Firewall Complex Form on it. This is a sustained ability, so it may be worth it to take the Focused Concentration positive quality or have a registered sprite sustain it for you for a number of combat rounds equal to its level.
- Same as #1, but have a machine sprite use its Diagnostics sprite power to assist in defending the device in addition to or instead of Infusion of Firewall. Getting any hits adds one to the limit for any task involving the device, and each hit adds a die to the pool for any task involving the device. A registered machine sprite can maintain Diagnostics indefinitely granting a permanent Firewall bonus, and it only costs a single task.
- Same as #1 or #2, but with a cyberdeck instead of a commlink. Prioritize the deck's Firewall matrix attribute. Slave all of the team's devices to it and then put an Agent program on it. This has the added bonus of being able to use the Agent (it gets its own initiative) to perform constant Matrix Perception tests and alert the TM if the PAN is under cyberattack by sending your Living Persona a message.
- The ComPac-Esprit General TacNet from Run & Gun provides a big boost to the Firewall, Data Processing, and Device Rating attributes of any commlink or cyberdeck to which it is installed.
Prior to Data Trails, unless you are actively using a commlink to access the Matrix (which is bad because you can't use Thread Complex Form or Compile/Register Sprite commands with anything other than your Living Persona), then you won't have any way to know that the commlink's PAN is under cyberattack without a machine sprite. However now you can use the Diagnostics commlink program (which doesn't have a price listed and can presumably be downloaded for free) to detect when the commlink's PAN is under cyberattack and the Bootstrap common cyber program (which you can get for your Living Persona with an echo) to perform a Format Device action on the commlink which rigs the commlink so that any time after it's rebooted, it sends your Living Persona a message whenever this happens. Format Device is a matrix action detailed on pages 239-240 of the Core Rulebook. Remember that as the owner of the commlink, you automatically have 4 marks on it. The Diagnostics commlink program and the Bootstrap common cyber program are both detailed on page 56 of Data Trails.
At first I thought Data Trails was a colossal disappointment for Technomancers. However, I have since decided it does have some slightly redeeming features, such a Bootstrap and the Otaku to Technomancer positive quality. It's still not as good as I would like it to be. There is also a new Technomancer supplement supposedly in the works. It should be out in a year or less, as of this answer's most recent update.