Monitor open connections
This command will plot open connections:
{ while true; do ss -ant | grep ESTAB | wc -l; sleep 0.1; done } | ttyplot
debug/
Monitor number of open sockets by a process
Example with watch command:
watch -n 1 'ps aux | kazy -i cmproxy -e kazy | kazy -r "[\d]+" -x | xargs -I % ls -l /proc/%/fd/ | kazy -i socket | wc -l'
Example with ttyplot command:
{ while true; do ps aux | kazy -i cmproxy -e kazy | kazy -r "[\d]+" -x | xargs -I % ls -l /proc/%/fd/ | kazy -i socket | wc -l; sleep 1; done } | ttyplot
Monitor DNS query time
{ while true; do dig google.com | kazy -i "Query time" | kazy -r -x "[\d.]*"; sleep 1; done } | ttyplot -t "dig to google.com"
Plot real time ping data in terminal
Install ttyplot:
grm install tenox7/ttyplot -n ttyplot
Ping plot:
ping 8.8.8.8 | sed -u 's/^.*time=//g; s/ ms//g' | ttyplot -t "ping to 8.8.8.8" -u ms
Log Varnish hash data
When starting Varnish, add -p vsl_mask=+Hash argument to the command. Print
varnish logs with this command:
sudo varnishlog -n /opt/varnish -q 'ReqURL ~ "my_request"'
Show top 10 process with open files
lsof | awk '{print $1}' | sort | uniq -c | sort -r -n | head
One liners to check open files limit
Check open files limit for the process named redis:
cat /proc/$(ps aux | grep redis | head -n 1 | kazy -x -r "\d+")/limits | kazy -i "open files" -i Limit
Check current number of open files for the process named redis:
sudo ls -l /proc/$(ps aux | grep redis | head -n 1 | kazy -x -r "\d+")/fd | wc -l
Open file limits
Print system limits:
14:53 $ ulimit -a
core file size (blocks, -c) unlimited
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 514130
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 514130
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
Print just open files limit
16:52 $ ulimit -Sn
1024
Get number of open files for a specific process:
# Get process id
16:56 $ ps aux | grep wshub
cobro 3200102 2.0 0.0 3676920 86488 ? Ssl 16:12 0:54 /opt/cobro/src/wshub/wshub -port 8015 -redis 127.0.0.1:6379 -auxport 8016
client 3212070 0.0 0.0 12132 1160 pts/0 S+ 16:57 0:00 grep --color=auto wshub
# Check current limits for the process
16:57 $ cat /proc/3200102/limits
Limit Soft Limit Hard Limit Units
Max cpu time unlimited unlimited seconds
Max file size unlimited unlimited bytes
Max data size unlimited unlimited bytes
Max stack size 8388608 unlimited bytes
Max core file size unlimited unlimited bytes
Max resident set unlimited unlimited bytes
Max processes 514130 514130 processes
Max open files 1024 262144 files
Max locked memory 65536 65536 bytes
Max address space unlimited unlimited bytes
Max file locks unlimited unlimited locks
Max pending signals 514130 514130 signals
Max msgqueue size 819200 819200 bytes
Max nice priority 0 0
Max realtime priority 0 0
Max realtime timeout unlimited unlimited us
# Print number of open files for the process
17:03 $ sudo ls -l /proc/3200102/fd | wc -l
157
Systemd needs this limit specified per service (otherwise it will be 1024):
[Service]
LimitNOFILE=2048
Check DNS propagation worldwide
Service from Constellix: DNS Propagation
Forward remote port to a local one via SSH tunnel
ssh -L <LOCAL_PORT>:127.0.0.1:<REMOTE_PORT> remote_server
TCP connections to <LOCAL_PORT> will be forwarded to 127.0.0.1:<REMOTE_PORT> on remote host remote_server