Tuesday, July 14, 2020

A "super ping" command to run while diagnosing network issues

Here's a bash function for your bash profile that continuously prints some basic checks I usually do while diagnosing network issues:

  • Show my LAN IPs
  • Show the default gateway IP
  • Ping the default gateway IP
  • Ping 8.8.8.8 (Google's public DNS servers)
  • DNS resolve amazon.com
  • Ping amazon.com
  • Get my WAN IP by curl'ing ifconfig.me

Tested on Ubuntu 20.04 and MacOS Catalina

function pingg() {
    while true; do
        printf "%s  " $(TZ=UTC date "+%Y-%m-%dT%H:%M:%S")

        if [[ "$OSTYPE" == "darwin"* ]]; then
            lanIps=$(ifconfig | grep "inet " | grep -v 127.0.0.1 | awk '{print $2}' | paste -d, -s -)
            gw=$(netstat -rn -f inet | grep default | awk '{print $2}')
        else
            lanIps=$(ip addr | grep "inet " | grep -v 127.0.0.1 | awk '{print $2}' | paste -d, -s -)
            gw=$(ip route | grep default | awk '{print $3}')
        fi
        printf "lanIp=%-15s " $lanIps
        printf "gw=%-15s " $gw

        pingGw="-------"
        if [ "$gw" != "" ]; then
            pingGw=$(ping -W1 -c1 $gw 2>/dev/null | tail -1 | grep -v "0 packets received" | cut -d '=' -f 2 | cut -d '/' -f 2)
            if [ "$pingGw" == "" ]; then
                pingGw="-------"
            fi
        fi
        printf "pGw=%-7s " $pingGw

        ping8888=$(ping -W1 -c1 8.8.8.8 2>/dev/null | tail -1 | grep -v "0 packets received" | cut -d '=' -f 2 | cut -d '/' -f 2)
        if [ "$ping8888" == "" ]; then
            ping8888="-------"
        fi
        printf "p8=%-7s " $ping8888

        dnsAmzn=$(host -4 -W 1 -t a amazon.com | head -n1 | grep "has address" | awk '{print $4}')
        if [ "$dnsAmzn" == "" ]; then
            dnsAmzn="-------"
        fi
        printf "dnsAmz=%-15s " $dnsAmzn

        pingAmzn="-------"
        if [ "$dnsAmzn" != "-------" ]; then
            pingAmzn=$(ping -W1 -c1 $dnsAmzn 2>/dev/null | tail -1 | grep -v "0 packets received" | cut -d '=' -f 2 | cut -d '/' -f 2)
            if [ "$pingAmzn" == "" ]; then
                pingAmzn="-------"
            fi
        fi
        printf "pAmz=%-7s " $pingAmzn

        wanIp="-------"
        dnsIfconfigMe=$(host -4 -W 1 -t a ifconfig.me | head -n1 | grep "has address" | awk '{print $4}')
        if [ "$dnsIfconfigMe" != "" ]; then
            wanIp=$(curl -s --max-time 2 --connect-timeout 2 -H "Host: ifconfig.me" $dnsIfconfigMe | head -n 1 | awk '{print $1'})
            if [ "$wanIp" == "" ]; then
                wanIp="-------"
            fi
        fi
        printf "wanIp=%-15s " $wanIp

        printf "\n"

        sleep 0.7
    done
}

Example output:

2020-07-13T23:43:59  lanIp=192.168.1.6/24 gw=192.168.1.1    pGw=0.264   p8=53.338  dnsAmz=176.32.98.166   pAmz=127.532 wanIp=1.2.3.4
2020-07-13T23:44:01  lanIp=192.168.1.6/24 gw=192.168.1.1    pGw=0.190   p8=47.107  dnsAmz=176.32.103.205  pAmz=111.309 wanIp=1.2.3.4
2020-07-13T23:44:02  lanIp=192.168.1.6/24 gw=192.168.1.1    pGw=0.290   p8=------- dnsAmz=176.32.103.205  pAmz=118.834 wanIp=1.2.3.4
2020-07-13T23:44:04  lanIp=192.168.1.6/24 gw=192.168.1.1    pGw=0.328   p8=143.387 dnsAmz=176.32.103.205  pAmz=135.333 wanIp=1.2.3.4
2020-07-13T23:44:06  lanIp=192.168.1.6/24 gw=192.168.1.1    pGw=0.313   p8=17.944  dnsAmz=176.32.103.205  pAmz=105.977 wanIp=1.2.3.4
2020-07-13T23:44:07  lanIp=192.168.1.6/24 gw=192.168.1.1    pGw=0.223   p8=22.505  dnsAmz=176.32.103.205  pAmz=97.623  wanIp=1.2.3.4
2020-07-13T23:44:08  lanIp=192.168.1.6/24 gw=192.168.1.1    pGw=0.250   p8=23.917  dnsAmz=176.32.103.205  pAmz=98.403  wanIp=1.2.3.4
2020-07-13T23:44:09  lanIp=192.168.1.6/24 gw=192.168.1.1    pGw=0.220   p8=41.262  dnsAmz=176.32.103.205  pAmz=100.828 wanIp=1.2.3.4

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