Collect the TCP configuration data in Linux

TCP config data

#!/bin/bash

#---------------------------------------------------------
# Usage: sudo ./collect_data.sh <network-interface-name>
#---------------------------------------------------------

# Define some variables
LOGFILE=/tmp/tcp_conf.log
DateStr=$(date +"%Y-%m-%d %H:%M:%S")

# Make shure the script is being executed with root privileges
if [[ "${UID}" -ne 0 ]]
then
  echo "Please run the script with sudo or as root. It's needed just for tcpdump in the very end of the script." >&2
  echo -e "\n\e[92mUsage: sudo ${0} <network-interface-name>\e[32m" >&2
  tput sgr0
  exit 1
fi

function print_line () {
  echo "--------------------------------------------------------------" >> $LOGFILE 2>&1
}

# Read the NIC
if [[ -z $1 ]]
then
  echo "The number of arguments passed to the script: $#"
  echo -e "\n\e[92mUsage: sudo ${0} <network-interface-name>\e[32m"
  ip a s | grep -E "inet.*brd|^[0-9]:" 
  tput sgr0
  read -p "Enter the name of NIC:" NIC
else
  NIC=$1
fi  

# Get the internal and external IPs
EXTERNAL_IP=$(curl ifconfig.me)
INTERNAL_IP=$(ip addr show ${NIC} | grep "inet " | awk '{print $2}' | cut -d / -f 1)


# Create a log file if it not exist
if [[ ! -f ${LOGFILE} ]]
then
  >"${LOGFILE}"
fi

uname -n >> $LOGFILE 2>&1
print_line
ip a s $NIC | grep -E "inet.*brd|^[0-9]:" >> $LOGFILE 2>&1
echo "External_ip: ${EXTERNAL_IP}" >> $LOGFILE 2>&1
print_line
free -m >> $LOGFILE 2>&1 
print_line
lshw -C network >> $LOGFILE 2>&1 
print_line


echo "$DateStr Internal IP: ${INTERNAL_IP}; External IP: ${EXTERNAL_IP} " >> $LOGFILE 2>&1

echo "$DateStr TCP buffer sizes:" >> $LOGFILE 2>&1
echo "tcp_mem: $(cat /proc/sys/net/ipv4/tcp_mem)" >> $LOGFILE 2>&1
print_line

echo "$DateStr the default and maximum amount for the receive socket memory:" >> $LOGFILE 2>&1
echo "rmem_default: $(cat /proc/sys/net/core/rmem_default)" >> $LOGFILE 2>&1
echo "rmem_max: $(cat /proc/sys/net/core/rmem_max)" >> $LOGFILE 2>&1
print_line

echo "$DateStr the default and maximum amount for the send socket memory:" >> $LOGFILE 2>&1
echo "wmem_default: $(cat /proc/sys/net/core/wmem_default)" >> $LOGFILE 2>&1
echo "wmem_default: $(cat /proc/sys/net/core/wmem_max)" >> $LOGFILE 2>&1
print_line

echo "$DateStr maximum amount of option memory buffers:" >> $LOGFILE 2>&1
echo "optmem_max: $(cat /proc/sys/net/core/optmem_max)" >> $LOGFILE 2>&1
print_line

echo "default congestion control is: $(sysctl net.ipv4.tcp_congestion_control)" >> $LOGFILE 2>&1
echo "list of congestion control algorithms that are available in the kernel: $(sysctl net.ipv4.tcp_available_congestion_control)" >> $LOGFILE 2>&1
echo "MTU probing is: $(sysctl net.ipv4.tcp_mtu_probing)" >> $LOGFILE 2>&1
echo "Fair queueing is: $(sysctl net.core.default_qdisc)" >> $LOGFILE 2>&1
echo "Window scaling is: $(sysctl net.ipv4.tcp_window_scaling)" >> $LOGFILE 2>&1
echo "Maximum number of packets, queued on the INPUT side: $(sysctl net.core.netdev_max_backlog )" >> $LOGFILE 2>&1
echo "========================================================================" >> $LOGFILE 2>&1

echo "TCP Socket memory usage:" >> $LOGFILE 2>&1
ss -tm >> $LOGFILE 2>&1

# Uncomment the below line to install the tcpdump utility
# command -v tcpdump >> $LOGFILE 2>&1 || apt install -y tcpdump
# or run this command manualy
# tcpdump -ttt -nni eth0 -s0 '(host <INTERNAL_IP> or <EXTERNAL_IP>) and (not port 22 or 53) and not icmp' -c 10000 -C 5000 -w /tmp/tcp_dump.pcap
# tcpdump -ttt -nni ${NIC} -s0 -w /tmp/tcp_dump.pcap -c 10000 -C 10000 host ${EXTERNAL_IP} and not port 22 and not port 53 and not icmp
tcpdump -tttt -nni ${NIC} -s0 -w /tmp/tcp_dump.pcap -c 10000 -C 10000 'not port 22 and not port 53 and not icmp'