A diagnostic of network configurations and connectivity issues for Gateway operators including IPv4/IPv6 forwarding status, firewall rules inspection, routing table examination

nym_network_diagnostics.sh

#!/bin/bash

echo "---------------------------------------"
echo
echo "checking IPv4 forwarding status..."
cat /proc/sys/net/ipv4/ip_forward

echo "---------------------------------------"
echo
echo "checking IPv6 forwarding status..."
cat /proc/sys/net/ipv6/conf/all/forwarding

echo "---------------------------------------"
echo
echo "checking UFW firewall Status..."
if command -v ufw >/dev/null; then
    ufw status verbose
else
    echo "UFW command not found. ufw may not be installed or configured."
fi

echo "---------------------------------------"
echo
network_device=$(ip route show default | awk '/default/ {print $5}')
if [ -z "${network_device}" ]; then
    echo "error: default network device not found."
    exit 1
fi
echo "network Device: $network_device"

echo "---------------------------------------"
echo
echo "inspecting IPv4 firewall rules..."
iptables -L FORWARD -v -n | awk -v dev="$network_device" '/^Chain FORWARD/ || /nymtun0/ && dev || dev && /nymtun0/ || /ufw-reject-forward/'

echo "---------------------------------------"
echo
echo "inspecting IPv6 firewall rules..."
ip6tables -L FORWARD -v -n | awk -v dev="$network_device" '/^Chain FORWARD/ || /nymtun0/ && dev || dev && /nymtun0/ || /ufw6-reject-forward/'

echo "---------------------------------------"
echo
echo "examining IPv4 routing table..."
ip route

echo "---------------------------------------"
echo
echo "examining IPv6 routing table..."
ip -6 route

echo "---------------------------------------"
echo
echo "checking IPv4 connectivity (example: google.com)..."
ping -c 4 google.com

echo "---------------------------------------"
echo
echo "checking IPv6 connectivity (example: google.com)..."
ping6 -c 4 google.com

echo "---------------------------------------"
echo
echo "checking internet and mixnet connectivity (IPv4) via nymtun0..."
echo "if a joke is returned there's connectivity through ipv4 and the nymtun, are you ready?"
sleep 2
# lets make this fun.....
curl -s -H "Accept: application/json" --interface $(ip addr show nymtun0 | grep 'inet ' | awk '{print $2}' | cut -d'/' -f1) https://icanhazdadjoke.com/ | jq -c .joke

echo "---------------------------------------"
echo
echo "checking Internet and mixnet connectivity (IPv6) via nymtun0..."
echo "if a joke is returned, there's connectivity through IPv6 and the nymtun. are you ready?"
sleep 2

ipv6_address=$(ip addr show nymtun0 | grep 'inet6 ' | awk '{print $2}' | cut -d'/' -f1 | grep -v '^fe80:')

if [ -z "$ipv6_address" ]; then
  echo 
  echo "no globally routable IPv6 address found on nymtun0."
  echo "please ensure IPv6 is enabled on your VPS or configure your security groups/firewall settings appropriately."
  echo "unfortunately there's no joke fo you :( and you can't route ipv6 traffic through your gateway to the internet"
else
  joke=$(curl -s -H "Accept: application/json" --interface "$ipv6_address" https://icanhazdadjoke.com/ | jq -c .joke)

  if [ -z "$joke" ] || [ "$joke" = "null" ]; then
    echo "failed to fetch a joke. there might be an issue with the Internet connectivity or the joke service."
  else
    echo "joke fetched successfully:"
    echo "$joke"
  fi
fi

echo "machine check complete"

Returns information like:

---------------------------------------

checking IPv4 forwarding status...
1
---------------------------------------

checking IPv6 forwarding status...
1
---------------------------------------

onspecting IPv4 firewall Rules...
Chain INPUT (policy ACCEPT 87M packets, 65G bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
1537K  360M ACCEPT     all  --  nymtun0 eth0    0.0.0.0/0            0.0.0.0/0           
1537K 1767M ACCEPT     all  --  eth0   nymtun0  0.0.0.0/0            0.0.0.0/0            state RELATED,ESTABLISHED

Chain OUTPUT (policy ACCEPT 86M packets, 65G bytes)
 pkts bytes target     prot opt in     out     source               destination         
---------------------------------------

inspecting IPv6 firewall Rules...
Chain INPUT (policy ACCEPT 60102 packets, 389M bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy ACCEPT 1 packets, 145 bytes)
 pkts bytes target     prot opt in     out     source               destination         
 480K   90M ACCEPT     all      nymtun0 eth0    ::/0                 ::/0                
 446K  591M ACCEPT     all      eth0   nymtun0  ::/0                 ::/0                 state RELATED,ESTABLISHED
    0     0 ACCEPT     all      eth0   nymtun0  ::/0                 ::/0                 state RELATED,ESTABLISHED
    0     0 ACCEPT     all      nymtun0 eth0    ::/0                 ::/0                

Chain OUTPUT (policy ACCEPT 52377 packets, 5605K bytes)
 pkts bytes target     prot opt in     out     source               destination         
---------------------------------------