Network testing with netcat (nc)
In order to pest whether is network port accessible, either udp or tcp.
Can server listen on udp port 5000 ?
Example with UDP port!
Server sidencat -ulp 5000
Client sidencat -u XXX.XXX.XXX.XXX 5000
debug
Check logs via systemd
journalctl -u service.name
Slow system boot reason
List systemd service start time systemd-analyze blame
Check gitlab status
Check complete gitlab status of running services
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production
Iptables traffic via rulles
Check iptables and their particular traffic
iptables -L -v
Network debug
Chek for crc error on network interfaceethtool -S "interface" |grep crcnetstat -iip -s link show
Possible Causes of Ethernet Errors
Linux debug
Check some of there in order to proceed with debugging
-T with time stampdmesg -T | grep -i error
cat /var/log/syslog | grep -i error
system monitoring
List of useful monitoring programs:
- vmstat
- lsof
- tcpdump
- netstat
- nload ethX
Virtual Memory Statistics
List Open Files
network packet analyzer
Network statistics
Netowork bandwidth
Connections on server per IP
Show connections on server per IP
Network statsnetstat -ntu | awk '{ print $5 }' | cut -d : -f 1 | sort | uniq -c | sort -nnetstat -tupan | awk -F '[: ]+' '{print $6}' |sort |uniq -c |sort -n