tcp-ping-port

A simple TCP ping utility to ping a port of an IP or domain.


Table of contents

---
- Benefits
- Installation
- How to use
- Dependencies
- API
- Testing

Benefits

---
Following are the pros and cons of this package compared to the regular ping

$3

- Can be used with Amazon Lambda functions and Aazure functions.
Regular ping uses ICMP protocol which is not permitted by AWS/Azure functions
- TCP packets have higher priorty than ICMP packets
- It can ping a particular port
- It can work even if ICMP is disabled

$3

- Higher data usage

| Protocol | Send (B)) | Receive (B) | Total (B) | Data saving |
| -------- | --------- | ------------ | ---------- | ----------- |
| TCP | 228 | 126 | 354 | 0% |
| ICMP | 98 | 98 | 196 | 45% |

The numbers are based on data reported by Wireshark

#### TCP Ping

| No. | Time | Source | Destination | Protocol | Length | Info |
| --- | ---- | ------ | ----------- | -------- | ------ | ---- |
| 1 | 0.000000 | x.x.x.x | y.y.y.y | DNS | 70 | Standard query 0xfe55 A google.com |
| 2 | 0.000393 | y.y.y.y | x.x.x.x | DNS | 86 | Standard query response 0xfe55 A google.com A 172.217.165.14 |
| | | | | | | |
| 3 | 0.001364 | x.x.x.x | 172.217.165.14 | TCP | 66 | 49985 → 80 [SYN] Seq=0 Win=64240 Len=0 MSS=1460 WS=256 SACK_PERM=1 |
| 4 | 0.012339 | 172.217.165.14 | x.x.x.x | TCP | 66 | 80 → 49985 [SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1430 SACK_PERM=1 WS=256 |
| 5 | 0.012412 | x.x.x.x | 172.217.165.14 | TCP | 54 | 49985 → 80 [ACK] Seq=1 Ack=1 Win=262912 Len=0 |
| 6 | 0.013110 | x.x.x.x | 172.217.165.14 | TCP | 54 | 49985 → 80 [FIN, ACK] Seq=1 Ack=1 Win=262912 Len=0 |
| 7 | 0.024927 | 172.217.165.14 | x.x.x.x | TCP | 60 | 80 → 49985 [FIN, ACK] Seq=1 Ack=2 Win=65536 Len=0 |
| 8 | 0.024987 | x.x.x.x | 172.217.165.14 | TCP | 54 | 49985 → 80 [ACK] Seq=2 Ack=2 Win=262912 Len=0 |

#### ICMP ping
| No. | Time | Source | Destination | Protocol | Length | Info |
| --- | ---- | ------ | ----------- | -------- | ------ | ---- |
| 1 | 0.000000 | x.x.x.x | y.y.y.y | DNS | 70 | Standard query 0xff9e A google.com|
| 2 | 0.003286 | y.y.y.y | x.x.x.x | DNS | 86 | Standard query response 0xff9e A google.com A 172.217.165.14|
| 3 | 0.040291 | x.x.x.x | 172.217.165.14| ICMP | 98 | Echo (ping) request id=0x0279, seq=1/256, ttl=128 (reply in 6)|
| 4 | 0.064258 | 172.217.165.14 | x.x.x.x | ICMP | 98 | Echo (ping) reply id=0x0279, seq=1/256, ttl=112 (request in 5)|

> NOTE: The first 2 DNS resolution calls are same in both cases for IPv4 and are not included in the total data usagage.

back to top

Installation

---
``
$ npm install tcp-ping-port --save
`
back to top

How to use

---

Simple examples
`js
const { tcpPingPort } = require("tcp-ping-port")

tcpPingPort("google.com").then(({online}) => {
// ....
})
`

With additional options
`js
const { tcpPingPort } = require("tcp-ping-port")
const dns = require('dns')
const options = {
socketTimeout: 11000,
dnsTimeout: 10000,
dnsServers: '8.8.8.8', // google DNS
}
tcpPingPort("google.com", 80, options).then(({online, ping}) => {
// ....
})
`

Check if host is offline
`js
const { tcpPingPort } = require("tcp-ping-port")

tcpPingPort("google.com").then(result => {
if (!result.online && result.error.code === 'TCPPINGTIMEOUT') {
// your code when host is not accessible....
}
})
`

back to top

Dependencies


* dns-fast-resolver - to resolve multiple domains at the same time and to handle any errors while resolving the domain name. Also, to skip the whole dns resolution if host name is an IP address.
* lodash
* maketype

back to top

API

$3

Attemps to open and close TCP connection

* hostname Host name or an IP address to try to connect to
* port Port number
* options