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firewall.go
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package singularity
import (
"fmt"
"log"
"os/exec"
"strconv"
)
// IPTablesRule is a struct representing a linux iptable firewall rule
type IPTablesRule struct {
srcAddr string
srcPort string
dstAddr string
dstPort string
srcPortRange string
v6 bool
}
// NewIPTableRule populate an iptables rule
func NewIPTableRule(srcAddr string, srcPort string,
dstAddr string, dstPort string, v6 bool) *IPTablesRule {
p := IPTablesRule{srcAddr: srcAddr, srcPort: srcPort,
dstAddr: dstAddr, dstPort: dstPort, v6: v6}
p.generateSourcePortRange(10)
return &p
}
// TODO Experimental
func (ipt *IPTablesRule) generateSourcePortRange(max int) {
i, err := strconv.Atoi(ipt.srcPort)
if err != nil {
log.Fatal(err)
}
if (i < 0) || (i > 65535) {
log.Fatal("Source port is not within an expected range")
}
maxPort := i + max
var maxPortString string
if maxPort > 65535 {
maxPortString = "65535"
} else {
maxPortString = strconv.Itoa(maxPort)
}
ipt.srcPortRange = fmt.Sprintf("%v:%v", ipt.srcPort, maxPortString)
}
func (ipt *IPTablesRule) makeAndRunRule(command string) {
iptables := "/sbin/iptables"
if ipt.v6 {
iptables = "/usr/sbin/ip6tables"
}
rule := exec.Command(iptables,
command, "INPUT", "-p", "tcp", "-j", "REJECT", "--reject-with", "tcp-reset",
"--source", ipt.srcAddr, //"--sport" srcPortRange,
"--destination", ipt.dstAddr, "--destination-port", ipt.dstPort)
err := rule.Run()
log.Printf("Firewall: `iptables` finished with return code: %v", err)
}
// AddRule adds an iptables rule in Linux iptable
func (ipt *IPTablesRule) AddRule() {
ipt.makeAndRunRule("-A")
}
// RemoveRule removes an iptables rule in Linux iptable
func (ipt *IPTablesRule) RemoveRule() {
ipt.makeAndRunRule("-D")
}