Nobody can log in

NetLab lab Advanced 3 tasks 30 points

R1 was set up for SSH with TACACS+ logins by a colleague who has since left. Now nobody gets in from the network: not with the server accounts and not with the local backup user (secret Back!Up2026). It should work like this:

SSH only (no Telnet), version 2, from the admin PC (10.1.1.10) only.
netadmin (on the TACACS+ server, key AAA!Key19) lands at privilege 15.

You still have the console, which asks for a user name too: try backup there. Find and fix every fault.

How it works: this is VulnTech NetLab, a network simulator running in your browser. Click a device in the diagram to open its console and type commands, just like on real equipment (? shows help, Tab finishes a word). Click a cable to inspect it. Tasks tick themselves off as you complete them; questions are answered in the box under each task. Your work is kept if you reload; Reset starts the network over.

Solution explanation

Three faults. There were no RSA keys, so SSH was disabled and port 22 refused every connection (show ip ssh). The vty ACL permitted 10.1.1.100 instead of 10.1.1.10. And the TACACS+ key had a lower-case k: the server ignored R1, so after the other two fixes only the local fallback would have worked. test aaa shows the difference between "no answer" and "rejected".

Show solution

[R1]
backup
Back!Up2026
enable
show ip ssh | include SSH
show access-lists
test aaa group tacacs+ netadmin Net!Admin19 legacy
configure terminal
crypto key generate rsa modulus 2048
no access-list 15
access-list 15 permit host 10.1.1.10
tacacs server AAA1
key AAA!Key19
exit
end
test aaa group tacacs+ netadmin Net!Admin19 legacy
[ADMIN]
ssh -l netadmin 10.1.1.1
Net!Admin19
show privilege
exit