
## 🧠 Everyday Network Troubleshooting: Tools You Should Know (and Actually Use)

![Networking Tools](/images/networking-tools.png)

Whether you're debugging why a pod can't reach an endpoint or trying to figure out why your app's requests are timing out, networking tools are your first line of defense.

Here’s a curated, opinionated, and battle-tested list of tools I use (almost) daily. Each one comes with practical examples.

## 🚀 Connectivity & Reachability

### 🔹 ping

Checks if a host is alive using ICMP echo requests.

```bash
ping google.com
ping -c 4 192.168.1.1 # -c 4 is to send 4 packets
```

🔧 Tip: If ping doesn't work, the host could be up but blocking ICMP. Check firewall rules.

### 🔹 traceroute

Visualise the path packets take to a remote host. Great for pinpointing bottlenecks.

```bash
traceroute google.com
traceroute -I 192.168.1.1 # -I is to use ICMP echo requests
```

🧠 Use case: “Why is latency high between service A and B?” → traceroute.

### 🔹 nslookup

Simple tool for querying DNS. Quick and dirty.

```bash
nslookup google.com
nslookup 8.8.8.8
```

### 🔹 dig

More verbose and powerful DNS query tool than nslookup.

```bash
dig google.com
dig google.com ANY # ANY is to get all records
dig google.com A +short # A is to get A records
dig google.com AAAA +short # AAAA is to get AAAA records
```

🧠 Bonus: Use +trace to debug DNS resolution path:

```bash
dig +trace google.com
dig +trace google.com +short # +short is to get the IP address
```

## 🌐 Port Scanning & TCP Checks

### 🔹 netcat (nc)

The Swiss Army Knife of TCP/UDP.

```bash
nc -zv google.com 80
nc -l 1234  # Listen on port 1234
nc -zv 192.168.1.1 1-65535 # -z is to scan all ports
```

📡 Tip: nc can be used to spin up fake HTTP servers or test port exposure in firewalled networks.

### 🔹 telnet

Old school, but works.

```bash
telnet google.com 80
```

🎯 Can be used to debug HTTP, SMTP, Redis manually.

## 🛠 Interface & Routing Info

### 🔹 ip (modern)

```bash
ip addr show
ip route show
ip link set eth0 up
```

### 🔹 ifconfig (legacy but familiar)

```bash
ifconfig
ifconfig eth0 up
```

### 🔹 route (macOS)

```bash
route -n
route add default gw 192.168.1.1
```

## 📊 Monitoring Traffic & Usage

### 🔹 netstat

```bash
netstat -an
netstat -r
```

### 🔹 ss (modern netstat replacement)

```bash
ss -tuln
ss -s
```

🔹 tcpdump
Capture packets like a boss.

```bash
tcpdump -i eth0
tcpdump -i eth0 -w capture.pcap
```

🎯 Combine with wireshark to visualize packets.

🔹 tshark
CLI version of Wireshark.

```bash
tshark -i eth0
tshark -r capture.pcap
```

### 🔹 vnstat

Track bandwidth usage.

```bash
vnstat -l
vnstat -d
```

### 🔹 nload / nethogs

Real-time network I/O monitor per interface or per process.

bash
```bash
nload
nethogs
```

## 📶 Wireless Tools

```bash
iw
iwlist
iwconfig
```

🧠 These are useful on laptops, Raspberry Pi setups, or Linux wireless APs.

## 🔐 Security, Scanning & Recon

### 🔹 nmap

Port scanner and network mapper.

```bash
nmap google.com
nmap -sP 192.168.1.0/24
```

🧠 Pro tip: Use with -A for OS detection, versioning, script scanning.

### 🔹 whois

Lookup domain ownership.

```bash
whois google.com
```

### 🔹 lsof

See what ports your system is listening on.

```bash
lsof -i :80
lsof -i tcp
```

### 🔹 arp / arping

```bash
arp -a
arp -d 192.168.1.1
```

```bash
arping 192.168.1.1
```

🧠 Use for static IP-to-MAC mapping debugging or LAN sniffing.

🧪 Bandwidth Testing
### 🔹 iperf
Client-server bandwidth tester.

```bash
iperf -s          # Start server
iperf -c <ip>     # Run client against server
```

📦 Works great for diagnosing slow internal links or tunnels.

### 🔹 mtr

Combines ping + traceroute with live stats.

```bash
mtr google.com
mtr google.com
mtr -r google.com
```

🧠 Instant visibility into jitter, loss, and latency by hop.

🧠 Bonus Mentions

```bash
conntrack – Show conntrack entries
ssdp – Debug multicast/UPnP
ncdu – Disk usage but worth knowing if you're debugging slow apps
hostname – Quick check or change the hostname
```

🎯 My Top 5 Daily Use Tools

| Purpose	| Tool |
| Ping test	| ping |
| DNS Resolution	| dig |
| Port connectivity	| nc / telnet |
| Interface info	| ip addr |
| Live traffic debug	| tcpdump |

✨ Final Thoughts

These tools are deceptively simple—but when chained together, they help you uncover:

- Firewall misconfigurations
- DNS issues
- Interface problems
- Packet loss/jitter
- Port blocks or misroutes
- Host reachability vs app-level downtime

🛠️ Bookmark this. Refer to it next time you're troubleshooting networking issues.

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