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使用avahi配置mdns/dns-sd网络发现samba/ftp

发布时间：April 4, 2022 // 分类： // No Comments

配置avahi使用mdns/dns-sd零配置发现samba/smb共享存储:

apt install avahi-daemon

cat <<EOF > /etc/avahi/services/smb.service
<?xml version="1.0" standalone='no'?>
<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<service-group>
  <name replace-wildcards="yes">Samba</name>
  <service>
    <type>_smb._tcp</type>
    <host-name>smb.haiyun.me.local</host-name>
    <port>445</port>  
    <txt-record>path=/share</txt-record>
    <txt-record>u=guest</txt-record>
    <txt-record>p=pass</txt-record>
  </service>
</service-group>
EOF
echo '192.168.168.1 smb.haiyun.me.local' >> /etc/avahi/hosts

ftp服务器：

cat <<EOF > /etc/avahi/services/ftp.service
<?xml version="1.0" standalone='no'?>
<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<service-group>
  <name replace-wildcards="yes">FTP</name>
  <service>
    <type>_ftp._tcp</type>
    <host-name>ftp.haiyun.me.local</host-name>
    <port>21</port>  
    <txt-record>path=/share</txt-record>
    <txt-record>u=guest</txt-record>
    <txt-record>p=pass</txt-record>
  </service>
</service-group>
EOF
echo '192.168.168.2 ftp.haiyun.me.local' >> /etc/avahi/hosts

注意：
1.host-name可使用FQDN标准域名，但是smb有的客户端不识别。
2.avahi默认会为hosts内目标ip添加反查域名，所以当在/etc/avahi/hosts内添加多个域名指向同一ip时会出错：

Static host name smb.haiyun.me.local: avahi_server_add_address failure: Local name collision

可以使用avahi-publish手工发布域名且不添加ip反查域名：

avahi-publish -a -R smb.haiyun.me.local 168.168.168.1

也可以修改systemd service让avahi启动时自动启动avahi-publish：

apt install avahi-utils
cat <<EOF > /usr/local/bin/avahi-host.sh
#!/bin/bash
/usr/bin/avahi-publish -a -R smb.haiyun.me.local 168.168.168.1 > /dev/null 2>&1 &
EOF
chmod +x /usr/local/bin/avahi-host.sh
sed -i '/ExecStart/aExecStartPost=\/usr\/local\/bin\/avahi-host\.sh' /lib/systemd/system/avahi-daemon.service

systemctl daemon-reload 
systemctl restart avahi-daemon.service 
#手工修改添加ExecStartPost=/usr/local/bin/avahi-host.sh
#systemctl edit --full avahi-daemon.service

使用dig测试mdns/dns-sd：

dig -p 5353 @224.0.0.251 ftp.haiyun.me.local
dig -p 5353 @224.0.0.251 _smb._tcp.local ptr
dns-sd -B _services._dns-sd._udp
dns-sd -B _smb._tcp
dns-sd -Z _smb._tcp
dns-sd -Q smb.haiyun.me.local
dns-sd -Q smb.haiyun.me.local aaaa

当同一ip有多个服务时也可使用基于golang dnssd的mdns/dns-sd服务：

package main

import (
        "context"
        "encoding/json"
        "fmt"
        "github.com/brutella/dnssd"
        "net"
        "os"
        "os/signal"
        "time"
)

type service struct {
        Name   string
        Type   string
        Domain string
        Host   string
        Ips    []string
        Port   int
        Text   map[string]interface{}
}

type config struct {
        Service []service
}

func main() {
        cfg_str, err := os.ReadFile("config.json")
        if err != nil {
                fmt.Println("load config file error:", err)
                os.Exit(1)
        }
        var cfg config
        err = json.Unmarshal(cfg_str, &cfg)
        if err != nil {
                fmt.Println("decode json err:", err)
                os.Exit(1)
        }

        if resp, err := dnssd.NewResponder(); err != nil {
                fmt.Println(err)
        } else {
                for _, v := range cfg.Service {
                        var ips []net.IP
                        for _, ip := range v.Ips {
                                ips = append(ips, net.ParseIP(ip))
                        }
                        text := make(map[string]string)
                        for key, value := range v.Text {
                                text[key] = fmt.Sprintf("%v", value)
                        }
                        sd_cfg := dnssd.Config{
                                Name:   v.Name,
                                Type:   v.Type,
                                Domain: v.Domain,
                                Host:   v.Host,
                                IPs:    ips,
                                Port:   v.Port,
                                Text:   text,
                        }

                        srv, err := dnssd.NewService(sd_cfg)
                        if err != nil {
                                fmt.Println(err)
                        }
                        go func() {
                                time.Sleep(1 * time.Second)
                                handle, err := resp.Add(srv)
                                if err != nil {
                                        fmt.Println(err)
                                } else {
                                        fmt.Printf("%s  Got a reply for service %s: Name now registered and active\n", time.Now().Format("2006-01-02 15:04:05"), handle.Service().ServiceInstanceName())
                                }
                        }()
                }

                ctx, cancel := context.WithCancel(context.Background())
                defer cancel()
                go func() {
                        stop := make(chan os.Signal, 1)
                        signal.Notify(stop, os.Interrupt)

                        select {
                        case <-stop:
                                cancel()
                        }
                }()

                err = resp.Respond(ctx)
                if err != nil {
                        fmt.Println(err)
                }
        }
}

配置文件保存到同目录config.json：

{
  "service":[
    {
      "name":"Samba",
      "type":"_smb._tcp",
      "domain":"local",
      "host":"smb.haiyun.me",
      "ips":[
        "10.0.0.1",
        "fdb2:808c:d0ef:0:20c:29ff:fe7c:264d"
      ],
      "port":445,
      "text":{
        "u":"user",
        "p":"pass",
        "path":"/share"
      }
    },
    {
      "name":"Ftp",
      "type":"_ftp._tcp",
      "domain":"local",
      "host":"ftp.haiyun.me",
      "ips":[
        "10.0.0.1",
        "fdb2:808c:d0ef:0:20c:29ff:fe7c:264d"
      ],
      "port":21,
      "text":{
        "u":"user",
        "p":"pass",
        "path":"/share"
      }
    }
  ]
}

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使用avahi配置mdns/dns-sd网络发现samba/ftp

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