TCP에 대한 응답이 있다고 하여도, 실제 handshake(연결 절차)가 정상적으로 이루어졌다고 단정할 수는 없습니다.


추가2: ICC 서버- 설치 인증서 관리- 인터넷 연결 안됨
추가 답변에 대한 제가 해볼 수 있는 테스트는 해본 듯 합니다.

아래의 내용으로도 도움이 안되면,
정확히 어떠한 증상(방법)으로 호스팅 업체에 문의 해야하는지 가이드 작성을 요청 드립니다.
단순히 2개 도메인에대한 80, 443이 방화벽이 문제인지 어떻게 제 서버에서 시도를 했는데 ipTIME까지 통신이 제대로 안되는지..
참고로 방화벽도 Off도 하고 테스트를 해봤습니다.

members.ipdisk.org
1.
~# nmap -Pn -p 80,443 --reason members.ipdisk.org
Starting Nmap 7.94SVN ( https://nmap.org ) at 2025-10-29 12:40 KST
Nmap scan report for members.ipdisk.org (211.115.202.150)
Host is up, received user-set (0.0025s latency).

PORT    STATE    SERVICE REASON
80/tcp  open     http    syn-ack ttl 45
443/tcp filtered https   no-response

Nmap done: 1 IP address (1 host up) scanned in 11.48 seconds

2-1.
~# curl -I http://members.ipdisk.org
HTTP/1.1 302 Found
Date: Wed, 29 Oct 2025 03:47:16 GMT
Server: Apache
Cache-Control: no-cache
Pragma: no-cache
X-UA-Compatible: IE=Edge
location: http://www.iptime.com/iptime/
Content-Type: text/html

2-2.
~# curl -I https://members.ipdisk.org
curl: (28) Failed to connect to members.ipdisk.org port 443 after 133819 ms: Couldn't connect to server


download.iptime.co.kr
1.
~# nmap -Pn -p 80,443 --reason download.iptime.co.kr
Starting Nmap 7.94SVN ( https://nmap.org ) at 2025-10-29 12:42 KST
Nmap scan report for download.iptime.co.kr (211.115.202.153)
Host is up, received user-set (0.0027s latency).

PORT    STATE SERVICE REASON
80/tcp  open  http    syn-ack ttl 45
443/tcp open  https   syn-ack ttl 45

Nmap done: 1 IP address (1 host up) scanned in 8.51 seconds

2-1.
~# curl -I http://download.iptime.co.kr
HTTP/1.1 200 OK
Date: Wed, 29 Oct 2025 03:52:33 GMT
Server: Apache
Last-Modified: Thu, 04 Sep 2014 01:27:48 GMT
ETag: "53-5023342a8a1e6"
Accept-Ranges: bytes
Content-Length: 83
Content-Type: text/html; charset=UTF-8

2-2.
:~# curl -I https://download.iptime.co.kr
HTTP/1.1 200 OK
Date: Wed, 29 Oct 2025 03:52:58 GMT
Server: Apache
Last-Modified: Thu, 04 Sep 2014 01:27:48 GMT
ETag: "53-5023342a8a1e6"
Accept-Ranges: bytes
Content-Length: 83
Content-Type: text/html; charset=UTF-8


3
:~# sudo tcpdump -i ens3 host members.ipdisk.org or host download.iptime.co.kr
명령 실행 후, ICC 웹에서 재시작 후, 버전 업그레이드, 설치 인증서 관리 메뉴를 클릭후 중지한 내용입니다

tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on ens3, link-type EN10MB (Ethernet), snapshot length 262144 bytes
13:04:12.866941 IP server.38756 > 211.115.202.150.33798: Flags [S], seq 2336357207, win 64240, options [mss 1460,sackOK,TS val 82444725 ecr 0,nop,wscale 7], length 0
13:04:26.073526 IP server.38748 > 211.115.202.153.http: Flags [S], seq 55066313, win 64240, options [mss 1460,sackOK,TS val 523925519 ecr 0,nop,wscale 7], length 0
13:04:26.076024 IP 211.115.202.153.http > server.38748: Flags [S.], seq 2288430257, ack 55066314, win 28960, options [mss 1460,sackOK,TS val 540887914 ecr 523925519,nop,wscale 7], length 0
13:04:26.076053 IP server.38748 > 211.115.202.153.http: Flags [.], ack 1, win 502, options [nop,nop,TS val 523925522 ecr 540887914], length 0
13:04:26.076084 IP server.38748 > 211.115.202.153.http: Flags [P.], seq 1:158, ack 1, win 502, options [nop,nop,TS val 523925522 ecr 540887914], length 157: HTTP: GET /release/rtw_icc/firmware/current_versions HTTP/1.1
13:04:26.078597 IP 211.115.202.153.http > server.38748: Flags [.], ack 158, win 235, options [nop,nop,TS val 540887916 ecr 523925522], length 0
13:04:26.079170 IP 211.115.202.153.http > server.38748: Flags [P.], seq 1:129, ack 158, win 235, options [nop,nop,TS val 540887917 ecr 523925522], length 128: HTTP: HTTP/1.1 304 Not Modified
13:04:26.079170 IP 211.115.202.153.http > server.38748: Flags [F.], seq 129, ack 158, win 235, options [nop,nop,TS val 540887917 ecr 523925522], length 0
13:04:26.079203 IP server.38748 > 211.115.202.153.http: Flags [.], ack 129, win 501, options [nop,nop,TS val 523925525 ecr 540887917], length 0
13:04:26.079239 IP server.38748 > 211.115.202.153.http: Flags [F.], seq 158, ack 130, win 501, options [nop,nop,TS val 523925525 ecr 540887917], length 0
13:04:26.081547 IP 211.115.202.153.http > server.38748: Flags [.], ack 159, win 235, options [nop,nop,TS val 540887919 ecr 523925525], length 0
13:04:54.014449 IP server.50684 > 211.115.202.153.http: Flags [S], seq 1373319165, win 64240, options [mss 1460,sackOK,TS val 523953460 ecr 0,nop,wscale 7], length 0
13:04:54.016844 IP 211.115.202.153.http > server.50684: Flags [S.], seq 3986289821, ack 1373319166, win 28960, options [mss 1460,sackOK,TS val 540915855 ecr 523953460,nop,wscale 7], length 0
13:04:54.016885 IP server.50684 > 211.115.202.153.http: Flags [.], ack 1, win 502, options [nop,nop,TS val 523953462 ecr 540915855], length 0
13:04:54.016924 IP server.50684 > 211.115.202.153.http: Flags [P.], seq 1:96, ack 1, win 502, options [nop,nop,TS val 523953463 ecr 540915855], length 95: HTTP: GET /icc/version HTTP/1.1
13:04:54.019066 IP 211.115.202.153.http > server.50684: Flags [.], ack 96, win 227, options [nop,nop,TS val 540915857 ecr 523953463], length 0
13:04:54.020042 IP 211.115.202.153.http > server.50684: Flags [P.], seq 1:210, ack 96, win 227, options [nop,nop,TS val 540915858 ecr 523953463], length 209: HTTP: HTTP/1.1 200 OK
13:04:54.020042 IP 211.115.202.153.http > server.50684: Flags [F.], seq 210, ack 96, win 227, options [nop,nop,TS val 540915858 ecr 523953463], length 0
13:04:54.020069 IP server.50684 > 211.115.202.153.http: Flags [.], ack 210, win 501, options [nop,nop,TS val 523953466 ecr 540915858], length 0
13:04:54.020159 IP server.50684 > 211.115.202.153.http: Flags [F.], seq 96, ack 211, win 501, options [nop,nop,TS val 523953466 ecr 540915858], length 0
13:04:54.022176 IP 211.115.202.153.http > server.50684: Flags [.], ack 97, win 227, options [nop,nop,TS val 540915860 ecr 523953466], length 0
13:04:57.036488 IP server.59910 > 211.115.202.153.http: Flags [S], seq 3921096195, win 64240, options [mss 1460,sackOK,TS val 523956482 ecr 0,nop,wscale 7], length 0
13:04:57.039284 IP 211.115.202.153.http > server.59910: Flags [S.], seq 2525905350, ack 3921096196, win 28960, options [mss 1460,sackOK,TS val 540918877 ecr 523956482,nop,wscale 7], length 0
13:04:57.039335 IP server.59910 > 211.115.202.153.http: Flags [.], ack 1, win 502, options [nop,nop,TS val 523956485 ecr 540918877], length 0
13:04:57.039395 IP server.59910 > 211.115.202.153.http: Flags [P.], seq 1:96, ack 1, win 502, options [nop,nop,TS val 523956485 ecr 540918877], length 95: HTTP: GET /icc/version HTTP/1.1
13:04:57.041322 IP 211.115.202.153.http > server.59910: Flags [.], ack 96, win 227, options [nop,nop,TS val 540918879 ecr 523956485], length 0
13:04:57.042222 IP 211.115.202.153.http > server.59910: Flags [P.], seq 1:210, ack 96, win 227, options [nop,nop,TS val 540918880 ecr 523956485], length 209: HTTP: HTTP/1.1 200 OK
13:04:57.042222 IP 211.115.202.153.http > server.59910: Flags [F.], seq 210, ack 96, win 227, options [nop,nop,TS val 540918880 ecr 523956485], length 0
13:04:57.042242 IP server.59910 > 211.115.202.153.http: Flags [.], ack 210, win 501, options [nop,nop,TS val 523956488 ecr 540918880], length 0
13:04:57.042358 IP server.59910 > 211.115.202.153.http: Flags [F.], seq 96, ack 211, win 501, options [nop,nop,TS val 523956488 ecr 540918880], length 0
13:04:57.044312 IP 211.115.202.153.http > server.59910: Flags [.], ack 97, win 227, options [nop,nop,TS val 540918882 ecr 523956488], length 0

끝.