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Linux Networking

IPs, listening ports, DNS, and quick connectivity checks.

  • linux network
  • ss ports
  • dig dns
  • curl check
  • ip addr

Linux Networking

IPs, listening ports, DNS, and quick connectivity checks.

Commands

CommandWhat it does
ip -br addrInterfaces and IPs, compact
ss -tlnpListening TCP ports and owners
ping -c3 example.comBasic reachability
dig +short example.comDNS resolution
curl -sSI https://example.comTLS plus headers check

Example

ip -br addr
ss -tlnp | grep 8080
dig +short api.example.com

FAQ

Port in use - who owns it?

ss with process flags shows the PID; stop it or bind your app elsewhere.

DNS works but curl hangs?

Likely a firewall issue: try a short connect timeout and check security groups.

คำถามที่พบบ่อย

Port in use - who owns it?
ss with process flags shows the PID; stop it or bind your app elsewhere.
DNS works but curl hangs?
Likely a firewall issue: try a short connect timeout and check security groups.

Linux

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Read ls output, chmod, chown, and sudo without breaking access.
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Linux grep and find
Find files by name, age, and size; search inside them fast.