SMTP Enumeration:

Under certain misconfiguration , we can gather info abt the host and networks

SMTP verbs: VRFY (Verify user) --- can be absued by attacker

Connect to host having mail server 

nc -nv 192.168.31.215 25 
VRFY bob
250 (Successful execution)
550 (Failure)

SNMP Enumeration (161):

SNMP misconfigurations can dramatically lead to loads of information leakage

Based on UDP

Susceptible to IP spoofing and replay attacks

SNMP MIB (SNMP Management Information base)

nmap -sU --open -p 161 192.168.31.200-254 --open

onesixtyone -c community -i ips

Prob and query using SNMPWALK

snmpwalk -c public -v1 192.168.31.227

So much of information .

To get specific information :

mid-value for running processes -- 1.3.6.1.2.1.25.4.2.1.2

snmpwalk -c public -v1 192.168.31.227 1.3.6.1.2.1.25.4.2.1.2
snmpwalk -c public -v1 192.168.31.227 1.3.6.1.2.1.6.13.1.3

tools -- snmpenum and snmpcheck -- capable of extracting info