Go language writing TCP scanner
TCP
- TCP, that is, Transmission Control Protocol.
TCP Handshake
- To establish a TCP connection (or open a port), you need 3 handshakes
Client -> Port Open -> Server
- syn (request to establish a new connection)
- syn-ack (Agree to create a new connection)
- ack (indicates a response)
- Closed Port
- client -syn-> Server
- Server -rst-> Client
- If a firewall exists
- Client βsyn (Timeout)β Firewall Server
Non-concurrent TCP scanner
Create a directory and create a file in that directory
~/Code/go via πΉ v1.20.3 via π base β mcd tcp-scanner Code/go/tcp-scanner via πΉ v1.20.3 via π base β go mod init go: cannot determine module path for source directory /Users/qiaopengjun/Code/go/tcp-scanner (outside GOPATH, module path must be specified) Example usage: 'go mod init /m' to initialize a v0 or v1 module 'go mod init /m/v2' to initialize a v2 module Run 'go help mod init' for more information. Code/go/tcp-scanner via πΉ v1.20.3 via π base β go mod init tcp-scanner go: creating new : module tcp-scanner Code/go/tcp-scanner via πΉ v1.20.3 via π base β c Code/go/tcp-scanner via πΉ v1.20.3 via π base β
document
package main
import (
"fmt"
"net"
)
func main() {
for i := 21; i < 120; i++ {
address := ("20.194.168.28:%d", i)
conn, err := ("tcp", address)
if err != nil {
("%s failed Closed\n", address)
continue
}
()
("%s connected open!!!\n", address)
}
}Concurrent TCP Scanner
package main
import (
"fmt"
"net"
"sync"
"time"
)
func main() {
start := ()
var wg
for i := 21; i < 120; i++ {
(1)
go func(j int) {
defer ()
address := ("20.194.168.28:%d", j)
conn, err := ("tcp", address)
if err != nil {
("%s closed\n", address)
return
}
()
("%s is open!!!\n", address)
}(i)
}
()
elapsed := (start) / 1e9
("\n\n%d seconds", elapsed)
}
// func main() {
// for i := 21; i < 120; i++ {
// address := ("20.194.168.28:%d", i)
// conn, err := ("tcp", address)
// if err != nil {
// ("%s failed closed\n", address)// continue
// }
// ()
// ("%s connected is open!!!\n", address)// }
// }Concurrent TCP Scanner - WORKER Pool
package main
import (
"fmt"
"sync"
)
func worker(ports chan int, wg *) {
for p := range ports {
("p", p)
()
}
}
func main() {
ports := make(chan int, 100)
var wg
for i := 0; i < cap(ports); i++ {
go worker(ports, &wg)
}
for i := 1; i < 1024; i++ {
(1)
ports <- i
}
()
close(ports)
}
// func main() {
// start := ()
// var wg
// for i := 21; i < 120; i++ {
// (1)
// go func(j int) {
// defer ()
// address := ("20.194.168.28:%d", j)
// conn, err := ("tcp", address)
// if err != nil {
// ("%s closed\n", address)// return
// }
// ()
// ("%s is open!!!\n", address)// }(i)
// }
// ()
// elapsed := (start) / 1e9
// ("\n\n%d seconds", elapsed)
// }
// func main() {
// for i := 21; i < 120; i++ {
// address := ("20.194.168.28:%d", i)
// conn, err := ("tcp", address)
// if err != nil {
// ("%s failed closed\n", address)// continue
// }
// ()
// ("%s connected is open!!!\n", address)// }
// }After optimization
package main
import (
"fmt"
"net"
"sort"
)
func worker(ports chan int, results chan int) {
for p := range ports {
address := ("20.194.168.28:%d", p)
conn, err := ("tcp", address)
if err != nil {
results <- 0
continue
}
()
results <- p
}
}
func main() {
ports := make(chan int, 100)
results := make(chan int)
var openports []int
var closeports []int
for i := 0; i < cap(ports); i++ {
go worker(ports, results)
}
go func() {
for i := 1; i < 1024; i++ {
ports <- i
}
}()
for i := 1; i < 1024; i++ {
port := <-results
if port != 0 {
openports = append(openports, port)
} else {
closeports = append(closeports, port)
}
}
close(ports)
close(results)
(openports)
(closeports)
for _, port := range closeports {
("%d closed\n", port)
}
for _, port := range openports {
("%d opened\n", port)
}
}
// func main() {
// start := ()
// var wg
// for i := 21; i < 120; i++ {
// (1)
// go func(j int) {
// defer ()
// address := ("20.194.168.28:%d", j)
// conn, err := ("tcp", address)
// if err != nil {
// ("%s closed\n", address)// return
// }
// ()
// ("%s is open!!!\n", address)// }(i)
// }
// ()
// elapsed := (start) / 1e9
// ("\n\n%d seconds", elapsed)
// }
// func main() {
// for i := 21; i < 120; i++ {
// address := ("20.194.168.28:%d", i)
// conn, err := ("tcp", address)
// if err != nil {
// ("%s failed closed\n", address)// continue
// }
// ()
// ("%s connected is open!!!\n", address)// }
// }This is the end of this article about writing TCP port scanner in Go (Golang). For more related contents of Go language TCP port scanner, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!