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Pair two machines ​

Pairing makes two computers trust each other for SSH. You do it once per pair of machines.

What pairing does ​

When you pair, the two apps agree on a secret and each shows a 6-digit code derived from it. If the codes match, nobody is sitting between the machines. Each side then sends the other its SSH user name, its CrossShell key and the identity keys of its SSH server, protected with a key only those two machines have.

The result:

  • Each machine can sign in to the other over SSH without a password.
  • Each machine already knows the other's identity, so there is no "trust this host?" question later.
  • If you allow screen sharing, each can view and control the other's screen.

Pair a machine that appears under Nearby ​

  1. Open CrossShell on both computers.

  2. On one of them, find the other under Nearby and select Pair.

  3. Compare the code in the Pairing with … dialog on both screens.

  4. If the codes are the same, select Codes match on both computers. If they differ, select Cancel.

You have about two minutes to confirm before the attempt times out.

Pair by address ​

Use this when the other machine does not appear under Nearby: it is on a different subnet, behind a firewall, or reached through a VPN.

  1. On the other machine, open CrossShell and note the IP address it shows.

  2. On this machine, select Pair by address.

  3. Enter that address under IP address and select Pair.

  4. Compare the codes and select Codes match on both computers.

If the other machine does not appear ​

  • Check that CrossShell is open on both computers.
  • Open This machine on each and look at Finding machines on the network and Accepting pairing requests. Discovery uses UDP port 47820 and pairing uses TCP port 47820.
  • Select Open firewall for the local network if it is offered.
  • Try Pair by address.

Check a connection ​

On a machine card, open More and select Check connection. CrossShell tests whether it can still reach and sign in to that machine.

Unpair ​

  1. On the machine card, open More and select Unpair.

  2. Confirm with Unpair.

Unpairing removes the other machine's key from this machine and, if the other machine is reachable, this machine's key from it. You can pair again at any time.

WARNING

If the other machine is off or unreachable when you unpair, its copy of the trust stays until you unpair there too. Unpair on both sides when you give away or lose a computer.

Next steps ​