copyright gloves n stuff.
No new security patches were issued after Cisco end-of-life for ISR G2 (announced 2020/2021). Using this in a current internet-facing role is not advisable without lockdown (no management from WAN, ACLs, COPP).
line vty 0 4 access-class MANAGEMENT-PERMIT in transport input ssh C3900-universalk9-mz.spa.157-3.m8.bin