xray的什么功能会随机监听一个UDP端口

[qcxiang]

这两天用命令“ss -tunlp|grep xray”观察到一个现象：
udp UNCONN 0 0 *:39745 : users:(("xray",pid=501,fd=3))
udp UNCONN 0 0 *:39767 : users:(("xray",pid=501,fd=10))
udp UNCONN 0 0 *:38152 : users:(("xray",pid=501,fd=34))
即间隔一会就会启动监听一个随机的UDP端口。

我使用XRAY的方式是通过caddy反代，xray监听的uinx domain socket，按照我肤浅的理解xray是不需要再监听其它TCP或者UDP的端口了。

服务端配置如下：
00_log.json
{
"log": {
"access": "/var/log/xray-access.log",
"error": "/var/log/xray.log",
"loglevel": "warning",
"dnsLog": true
}
}

01_dns.json
{
"dns": {
"hosts": {
"dns.google": ["8.8.8.8", "8.8.4.4"],
"cloudflare-dns.com": ["1.1.1.1", "1.0.0.1"],
"geosite:category-ads-all": "127.0.0.1"
},
"servers": [
{
"address": "https+local://dns.google/dns-query",
"domains": ["geosite:geolocation-!cn"],
"skipFallback": true
},
{
"address": "https+local://cloudflare-dns.com/dns-query",
"skipFallback": false
}
],
"queryStrategy": "UseIPv4",
"disableCache": false,
"disableFallback": false,
"disableFallbackIfMatch": true
}
}

02_inbounds.json
{
"inbounds": [
{
"listen": "@xxxxxxxxxx",
"protocol": "vless",
"settings": {
"clients": [
{
"id": "xxxxxxxxxxx"
}
],
"decryption": "none"
},
"streamSettings": {
"network": "h2",
"security": "none",
"httpSettings": {
"host": ["xxx.xxx"],
"path": "/xxx"
}
},
"sniffing": {
"enabled": true,
"destOverride": ["http", "tls"]
}
}
]
}

03_routing.json
{
"routing": {
"domainStrategy": "UseIp",
"domainMatcher": "hybrid",
"rules": [
{
"type": "field",
"ip": ["geoip:private", "geoip:cn"],
"outboundTag": "Block"
},
{
"type": "field",
"outboundTag": "Out-direct",
"network": "tcp,udp"
}
]
}
}

04_outbounds.json
{
"outbounds": [
{
"tag": "Out-direct",
"protocol": "freedom",
"settings": {
"domainStrategy": "UseIPv4"
}
},
{
"tag": "Block",
"protocol": "blackhole",
"settings": {
"response": {
"type": "none"
}
}
}
]
}

[RPRX]

“代理 UDP 流量”的功能