Poloniex continue credit to old address just need wait long time between 24 and 48H .

You can confirme credit now ?

sorry to say that someone told me OP is scammer. i wanted to buy but i dont

That's fine.  I'm understanding you ok.   If you really trust your friend and you believe he can solve, and there isn't a lot of risk, add him as admin temporarily and let him have a look.  You can change passwords, 2FA, etc after. 

Another alternative is to test small scale at another location you OWN, testbed, maybe at home, behind any decent recent router that can drop DOS attacks.  Change a bunch of stuff, different mining account, wallet, etc, for that and then you will possibly have more time for you and\or him to try to poke and prod at something that stays running without getting shut down real fast.

Baby steps.

Iptables has a couple counterintuitive concepts that aren't flat apparent, reminds me of a crazy commission determination engine I worked on once.  I can't give you a better answer than that because I'm not highly knowledgeable about it myself and my unix machines are all fine now and it's been awhile since I had an iptables problem.  I **think** I solved my last issue by an answer at stackexchange.

You can keep digging at iptables via that suggestion and you may find your answer, but DDOS attack and protection is very hard even for the folks that are experts in that or can throw lots of money to those folks to help.  Honestly I'd start with switching VPS to one that provides DDOS as part of the package if I couldn't solve in a couple days.  Sometimes throwing money at it *IS* the best way to solve a problem.

It uses the port you tell it to. -o OR -x options are relevant depending on your proxy situation or not.  You have to use ports specified by the mining server as available for use, they often vary greatly depending on the pool.

minerd --help
Usage: minerd [OPTIONS]
Options:
  -a, --algo=ALGO       specify the algorithm to use
                          scrypt    scrypt(1024, 1, 1) (default)
                          sha256d   SHA-256d
                          X11       Xcoin
  -o, --url=URL         URL of mining server (default: http://127.0.0.1:9332/)
  -O, --userpass=U:P    username:password pair for mining server
  -u, --user=USERNAME   username for mining server
  -p, --pass=PASSWORD   password for mining server
      --cert=FILE       certificate for mining server using SSL
  -x, --proxy=[PROTOCOL://]HOST[:PORT]  connect through a proxy
  -t, --threads=N       number of miner threads (default: number of processors)
  -r, --retries=N       number of times to retry if a network call fails
                          (default: retry indefinitely)
  -R, --retry-pause=N   time to pause between retries, in seconds (default: 30)
  -T, --timeout=N       network timeout, in seconds (default: 270)
  -s, --scantime=N      upper bound on time spent scanning current work when
                          long polling is unavailable, in seconds (default: 5)
      --no-longpoll     disable X-Long-Polling support
      --no-stratum      disable X-Stratum support
  -q, --quiet           disable per-thread hashmeter output
  -D, --debug           enable debug output
  -H, --hashdebug       enable hash debug output
  -P, --protocol-dump   verbose dump of protocol-level activities
  -S, --syslog          use system log for output messages
  -B, --background      run the miner in the background
      --benchmark       run in offline benchmark mode
  -c, --config=FILE     load a JSON-format configuration file
  -V, --version         display version information and exit
  -h, --help            display this help text and exit