openwrt的ddns-script验证mix-port会卡在代理验证上，本来以为是mixd-port问题，后来发现是openwrt的nc命令可能存在问题，这里给出一个workaround，绕过代理验证。

编辑dynamic_dns_functions.sh，直接修改 local __ERR=0 即可

nano /usr/lib/ddns/dynamic_dns_functions.sh

 # analyze and verify given proxy string
 # $1    Proxy-String to verify
 verify_proxy() {
         #       complete entry          user:password@host:port
         #                               inside user and password NO '@' of ":" allowed
         #       host and port only      host:port
         #       host only               host            ERROR unsupported
         #       IPv4 address instead of host    123.234.234.123
         #       IPv6 address instead of host    [xxxx:....:xxxx]        in square bracket
         local __TMP __HOST __PORT
         local __ERR=0 255 # last error buffer
         local __CNT=0   # error counter

         [ $# -ne 1 ] && write_log 12 "Error calling 'verify_proxy()' - wrong number of parameters"
         write_log 7 "Verify Proxy server 'http://$1'"

         # try to split user:password "@" host:port
         __TMP=$(echo $1 | awk -F "@" '{print $2}')
         # no "@" found - only host:port is given
         [ -z "$__TMP" ] && __TMP="$1"
         # now lets check for IPv6 address
         __HOST=$(echo $__TMP | grep -m 1 -o "$IPV6_REGEX")
         # IPv6 host address found read port
         if [ -n "$__HOST" ]; then
                 # IPv6 split at "]:"
                 __PORT=$(echo $__TMP | awk -F "]:" '{print $2}')
         else
                 __HOST=$(echo $__TMP | awk -F ":" '{print $1}')
                 __PORT=$(echo $__TMP | awk -F ":" '{print $2}')
         fi
         # No Port detected - EXITING
         [ -z "$__PORT" ] && {
                 [ -n "$LUCI_HELPER" ] && return 5
                 write_log 14 "Invalid Proxy server Error '5' - proxy port missing"
         }

         while [ $__ERR -gt 0 ]; do
                 verify_host_port "$__HOST" "$__PORT"
                 __ERR=$?
                 if [ -n "$LUCI_HELPER" ]; then  # no retry if called by LuCI helper script
                         return $__ERR
                 elif [ $__ERR -gt 0 -a $VERBOSE -gt 1 ]; then   # VERBOSE > 1 then NO retry
                         write_log 4 "Verify Proxy server '$1' failed - Verbose Mode: $VERBOSE - NO retry on error"
                         return $__ERR
                 elif [ $__ERR -gt 0 ]; then
                         __CNT=$(( $__CNT + 1 )) # increment error counter
                         # if error count > retry_count leave here
                         [ $retry_count -gt 0 -a $__CNT -gt $retry_count ] && \
                                 write_log 14 "Verify Proxy server '$1' failed after $retry_count retries"

                         write_log 4 "Verify Proxy server '$1' failed - retry $__CNT/$retry_count in $RETRY_SECONDS seconds"
                         sleep $RETRY_SECONDS &
                         PID_SLEEP=$!
                         wait $PID_SLEEP # enable trap-handler
                         PID_SLEEP=0
                 fi
         done
         return 0
 }