SSHポートフォワーディングFTP (FTP over SSHとも言う)とSFTPの主な違いについてIBM i OSユニークな点も含めて下表に纏める。
This cafe is very convenient for me to get free Wi-Fi and it is called “METRO FREE Wi-Fi“, because it is close to Nishi-Shinjuku metro station. By the way, before users are authorized by the server, users can send ping any destination but aren’t allowed to transfer any TCP/IP packets. It’s to be expected that the provider wants to restrict the unauthorized user to prevent any unexpected and malicious behavior.
Logs of ping and ssh before I start to authorize:
$ ping google.co.jp
PING google.co.jp (22.214.171.124): 56 data bytes
64 bytes from 126.96.36.199: icmp_seq=0 ttl=47 time=14.569 ms
64 bytes from 188.8.131.52: icmp_seq=1 ttl=50 time=10.830 ms
--- google.co.jp ping statistics ---
3 packets transmitted, 2 packets received, 33.3% packet loss
round-trip min/avg/max/stddev = 10.830/12.700/14.569/1.869 ms
$ ssh yukun.info
^C # <-- I can't connect the server.
We started from 9:00 and ended at 21:00 (12 hours!) so I was very exhausted but I was so excited when I was able to solve the parts of some problems. Moreover, I could improve my security skills and recognize my weak points in the field. It was a very valuable event. When I have a chance to attend such competition in the near future, I’ll participate again and of course, I’ll prepare by improving my skill every day to contribute.