# Network debugging ping -c 4 tpa-1.domain.com traceroute tpa-1.domain.com nc -zv tpa-1.domain.com 22 # Port check nslookup tpa-1.domain.com # SSH debugging ssh -vvv root@tpa-1.domain.com # Check bridges and VLANs brctl show ip link show type vlan ip link show type bridge # Storage debugging lvs # List logical volumes pvs # List physical volumes vgs # List volume groups cat /proc/mdstat # RAID status # Process debugging strace -p <pid> lsof -p <pid> lsof -i :22 # Processes using port 22 # System resources free -h vmstat 1 iostat -x 1