ubuntu - iptables block outgoing request from php

We have a Ubuntu server that host a php server and game server. recently, we get a lot of dos and flood attack. so i find some rule for iptables can protect http and game port from attack.

here is my rules:

iptables -F
iptables -P INPUT DROP
iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -i eth0 -p tcp -m state --state NEW -m limit --limit 5/sec -m connlimit --connlimit-upto 15 --connlimit-mask 32 --connlimit-saddr -j ACCEPT
iptables -A INPUT -i eth0 -p tcp -m tcp --dport 22 -m state --state RELATED,ESTABLISHED -m connlimit --connlimit-upto 15 --connlimit-mask 32 --connlimit-saddr -j ACCEPT
iptables -A INPUT -i eth0 -p tcp -m tcp --dport 80 -m state --state RELATED,ESTABLISHED -m connlimit --connlimit-upto 15 --connlimit-mask 32 --connlimit-saddr -j ACCEPT
iptables -A INPUT -i eth0 -p tcp -m tcp --dport 443 -m state --state RELATED,ESTABLISHED -m connlimit --connlimit-upto 15 --connlimit-mask 32 --connlimit-saddr -j ACCEPT
iptables -A INPUT -i eth0 -p tcp -m tcp --dport 3724 -m state --state RELATED,ESTABLISHED -m connlimit --connlimit-upto 15 --connlimit-mask 32 --connlimit-saddr -j ACCEPT
iptables -A INPUT -i eth0 -p tcp -m tcp --dport 25 -m state --state RELATED,ESTABLISHED -m connlimit --connlimit-upto 15 --connlimit-mask 32 --connlimit-saddr -j ACCEPT
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but the problem appear when php want to open a request like Soap WebService to another server. and iptables block this connection.

I think that problem is in this line :

iptables -P INPUT DROP
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but without this line all request to all other port are allowed.

and this is php Soap error :

object(SoapClient)#48 (2) { ["_soap_version"]=> int(1) ["sdl"]=> resource(97) of type (Unknown) }
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I appreciate all your comment. Thanks.