How to use globbing in ssh config to connect via SSH tunnel?

Question

I have configured ~/.ssh/config file on localhost:

### First jump host. Directly reachable
Host ServerA
    Hostname 10.0.5.101
    User jenny
    IdentityFile /home/admin/.ssh/serverA

### Second jumphost. Only reachable via 10.0.5.101
Host ServerB1
  HostName ServerB1
  User james
  ProxyJump ServerA
  IdentityFile /home/admin/.ssh/james

### Host only reachable via serverA and ServerB1
Host ServerC1
  HostName ServerC1
  User root
  ProxyJump ServerB1
  IdentityFile /home/admin/.ssh/ServerC1

I can directly connect to ServerC1 using ssh ServerC1 command from localhost using the config above.

The issue is that there are many ServerB's and each ServerB is connected to several ServerC's. The private keys are the same for all the Servers so that's not the issue.

From localhost, I want to connect via SSH tunnel to any of ServerC1,2,3..n

ServerA /etc/hosts has all the hostname and IPs for ServerB's and each ServerB has IPs of ServerC's in it's /etc/hosts file.

Can I use pattern matching in my localhost's ~/.ssh/config file to accomplish this? Currently I am limited to connecting ServerC1 only because I specifically specified ServerB1 and ServerC1

Answer 1

After some help from reddit, the best answer to this problem is configuring the ~/.ssh/config file as follows: Assuming all of the ServerB* has same IdentityFile.

Host ServerA
    Hostname 10.0.5.101
    User jenny
    IdentityFile /home/admin/.ssh/serverA

Match originalhost ServerB*
    User james
    ProxyJump ServerA
    IdentityFile /home/admin/.ssh/james

And then at command-line:

ssh -J serverB1 -i /home/admin/.ssh/ServerC1 root@ServerC1