- severity levels
- 0: emergency ≡ system may be unusable
- 1: alert ≡ immediate action
- 2: critical
- 3: error
- 4: warning
- 5: notification ≡ normal, significant
- 6: informational ≡ normal
- 7: debugging (default for console, monitor, buffered)
- banners
- MOTD: always appears
- login: VTY, before authC (does not appear in console)
- enable: VTY, after authC
- UDP 514, TCP 601
- message length limit – 1024 bytes (including IP header)
(config)# logging trap [<LEVEL>]
(config)# logging console [<LEVEL>]
(config)# logging buffered [<LEVEL>] [<SIZE>]
(config)# logging <IP>
; log somewhere besides console
(config)# logging on
; limits entries inlog per second, except LEVEL and lower
(config)# logging rate-limit <mps> [except <LEVEL>]
(config)# service timestamps log datetime|uptime ...
(config)# service sequence-numbers
(config)# banner motd
(config)# banner login
(config)# banner exec
; EVENT = link-status, spanning-tree, ...
(config-if)# logging event <EVENT>
; 10 default, for all sessions
(config-line)# history size <N>
(config-line)# logging synchronous
(config-line)# exec-timeout 0 0
# show logging
# show history
; increase for this session only
# terminal history size <N>