ISP에서 포트를 막은듯 한데 어찌 방법이 없을까요..?

대부분의 ISP 업체들이 80과 21번 포트를 막아 놓는다고 합니다.
22번 포트까지 막는다는 말은 못들었는데..

윗 분의 말씀대로 전화로 압박하는게 가장 효과적일껍니다.

아니면 해당 ISP의 고객게시판에 막 화가 난 것처럼 해서 글을 올리면
금방 해결해 주기도 합니다. (제가 사용하던 하나로가 그랬죠. ^^;;)

tcp traceroute 를 이용해서 isp 에서 필터링을 하였는지 확인 가능합니다.

[url]http://www.MainNerve.com/lft/[/url]
LFT (formerly FFT) is an alternative traceroute program for displaying the route packets take to an IP network host/socket. Unlike Van Jacobson's traceroute, which is available on almost every platform today, LFT uses TCP in order to elicit ICMP TIME_EXCEEDEDs or other IP route data. As a result, LFT often executes much faster and sees behind some configurations of firewalls. Its stateful engine lets the user know when it encounters a stateful firewall or other interesting conditions. It also does AS number and netblock name lookups en route. Most importantly, LFT can trace specific TCP-based protocol routes (not just IP) to assist network engineers with manual fault isolation of network application problems.

http://michael.toren.net/code/tcptraceroute/
tcptraceroute is a traceroute implementation using TCP SYN packets, instead of the more traditional UDP or ICMP ECHO packets. In doing so, it is able to trace through many common firewall filters.

nmap 이나 텔넷등을 이용한 호스트의 포트 상태확인은 방화벽이나 라우터에서 필터링되었을경우 정확한 상태확인이 어렵습니다.

호스트의 문제인지, 상단 방화벽이나 라우터에서의 필터링인지 확인이 안됩니다.

~>lft -V

LFT - the alternative traceroute tool for network (reverse) engineers

Usage: lft [<options>] [<gateway> <...>] <hostname:dport>

Options are:
  -d <dport>       destination port number
  -s <sport>       source port number
  -m <min>         minimum number of probes to send per host
  -M <max>         maximum number of probes to send per host
  -a <ahead>       number of hops forward to query before receiving replies
  -c <scatter ms>  minimum number of milliseconds between subsequent queries
  -t <timeout ms>  maximum RTT before assuming packet was dropped
  -l <min ttl>     minimum TTL to use on outgoing packets
  -q <sequence>    set the initial sequence number (ISN)
  -D <device/ip>   network device (name or IP address) to use (e.g., "en1")
  -H <ttl>         maximum number of hops to traverse (max TTL of packets)
  -i               disable "stop on ICMP" other than TTL expired
  -n               disable use of the DNS resolver to display hostnames
  -F               enable use of FIN packets only (defaults are SYN)
  -N               enable lookup and display of network names
  -A               enable lookup and display of Autonomous System numbers
  -T               enable display of LFT's execution timer
  -S               suppress the status bar (only show the completed trace)
  -V               print a lot of debugging garbage including packets
  -E               enable LFT's stateful Engine to detect firewalls
  -v               show version information

Default is: lft -d 80 -m 1 -M 3 -a 5 -c 20 -t 1000 -H 30 -s 53

~>lft naver.com:80

Tracing ___________________.

TTL  LFT trace to 211.218.150.200:80/tcp
 1   lanbird (192.168.0.1) 23.3ms
 2   211.196.201.73 46.6ms
 3   211.196.201.76 51.0/*ms
 4   center2-youngdong1-2500m.kornet.net (168.126.109.5) 43.8ms
 5   220.73.150.42 46.2ms
 6   168.126.109.194 56.2ms
 7   218.145.29.229 44.0ms
 8   [target] 211.218.150.200:80 52.3ms

~>lft naver.com:22

Tracing ____________________________________________

LFT can't seem to round-trip.  Local packet filter in the way?

TTL  LFT trace to 211.218.150.200:22/tcp
 1   lanbird (192.168.0.1) 24.8ms
 2   211.196.201.73 48.9ms
 3   211.196.201.58 51.7/*ms
 4   center2-youngdong1-2500m.kornet.net (168.126.109.5) 46.5ms
 5   220.73.150.42 50.2ms
 6   168.126.109.194 45.0ms
**   [22/tcp failed]  Try alternate options or use -V to see packets.

22 와 80 에 대한 lft 결과를 비교해보시면 22 는 호스트 이전에 필터링 됨을 확인할수 있습니다.