IPTables：允许传出SSH

当你有一个传出连接时，目标端口将是22，所以这应该是规则：

 $IPT -A OUTPUT -o eth0 -p tcp --dport 22 -j ACCEPT 

另外，您应该有一条规则来覆盖INPUT和OUTPUT链上的ESTABLISHED和RELATED ：

 $IPT -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT $IPT -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT 

希望这可以帮助。

您的传出SSHstream量的规则不包括启动传出连接所需的NEW语句。

当您不了解客户端 – 服务器体系结构和“状态防火墙”时，这是一个经典错误

在客户端 – 服务器体系结构中，唯一已知的端口是目标端口，因为客户端select了一个临时端口1 ，除了一些非常罕见的例外，例如DHCP。

从防火墙的angular度来看，从TCP驱动的每个数据包都具有NEW状态，特别是在TCP连接中。 2

首先让我们看看我们有什么

 IPT=/sbin/iptables $IPT -F $IPT -X $IPT -t nat -F $IPT -t nat -X $IPT -t mangle -F $IPT -t mangle -X $IPT -P INPUT DROP $IPT -P FORWARD DROP $IPT -P OUTPUT DROP # Excellent!! because always we need to accept this kind of states because # always are response packets, remember we can be client or server $IPT -A INPUT -m state --STATE ESTABLISHED,RELATED -j ACCEPT $IPT -A OUTPUT -m state --STATE ESTABLISHED,RELATED -j ACCEPT # Allow All for SSH # this accept ssh connections from outside, and the response for this input # is a outgoing packet with the state ESTABLISHED. (four lines above) $IPT -A INPUT -i eth0 -p tcp --dport 22 -j ACCEPT # this rule are meaningless because you never start a ssh connection from # source port 22, this because the source ports are choose randomly $IPT -A OUTPUT -o eth0 -p tcp --sport 22 -j ACCEPT # this one let start a ssh connection from within to the outside and the response # enter in state ESTABLISHED, 13 lines above $IPT -A OUTPUT -o eth0 -p tcp --dport 22 -j ACCEPT # Allow all for HTTP / HTTPS # http servers are very basic if we think on client-server, they only respond a # client request, except if some web software try to establish a network connection # to the outside, for this block the only rule with meaning is the first, the rest are # meaningless $IPT -A INPUT -i eth0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT $IPT -A OUTPUT -o eth0 -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT $IPT -A OUTPUT -o eth0 -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT $IPT -A INPUT -i eth0 -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT # Allow loopback traffic # this are obligatory rules avoiding the firewall block himself $IPT -A INPUT -i lo -j ACCEPT $IPT -A OUTPUT -o lo -j ACCEPT # Allow to be pinged ( Outside => srv ) # always the interpretation depends from the point of view # with this rules you can accept ping request from outside and despond the request # but you cannot ping from inside to outside because in that scenario you send the request (OUTPUT) # and receive a reply from outside (INPUT) $IPT -A INPUT -p icmp --icmp-type echo-request -j ACCEPT $IPT -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT # Allow outgoing DNS connections # this allow send dns queries to the DNS server that you have registered in the file # /etc/resolv.conf $IPT -A OUTPUT -p udp -o eth0 --dport 53 -j ACCEPT # this one are meaningless because the response from the DNS server is ESTABLISHED and is # accepted in the very beginning in the firewall $IPT -A INPUT -p udp -i eth0 --sport 53 -j ACCEPT # Apt-get # AFAIK apt use http or ftp, they can use https but is less common # the specification of a range on source port are meaningless $IPT -A OUTPUT -p tcp --dport 80 --sport 32786:61000 -j ACCEPT $IPT -A INPUT -p tcp --dport 80 --sport 32786:61000 -j ACCEPT $IPT -A OUTPUT -p tcp --dport 32786:61000 --sport 80 -j ACCEPT $IPT -A INPUT -p tcp --dport 32786:61000 --sport 80 -j ACCEPT # SMTP Outgoing # I don't known why you start adding more criteria without meaning # maybe you start surfing on the net and starting copy&paste code without see what you are doing # always when yo need to learn something go to the root, or in this case to www.netfilter.org $IPT -A OUTPUT -p tcp --sport 1024:65535 -d 0/0 --dport 25 -m state --state NEW,ESTABLISHED -j ACCEPT $IPT -A INPUT -p tcp -s 0/0 --sport 25 --dport 1024:65535 -m state --state ESTABLISHED-j ACCEPT # the rules below are.... copy&paste from somewhere # Prevent DoS #$IPT -A INPUT -p tcp --dport 80 -m limit --limit 60/minute --limit-burst 150 -j ACCEPT $IPT -A INPUT -p tcp --dport 80 -m connlimit --connlimit-above 100 --connlimit-mask 32 -j REJECT --reject-with tcp-reset # # Log dropped packets $IPT -N LOGGING $IPT -A INPUT -j LOGGING $IPT -A LOGGING -m limit --limit 2/min -j LOG --log-prefix "IPTables Packet Dropped: " --log-level 7 $IPT -A LOGGING -j DROP 

所以，对我来说，你需要这个防火墙

 IPT=/sbin/iptables $IPT -F $IPT -X $IPT -t nat -F $IPT -t nat -X $IPT -t mangle -F $IPT -t mangle -X $IPT -P INPUT DROP $IPT -P FORWARD DROP $IPT -P OUTPUT DROP # accept a priori all the responses $IPT -A INPUT -m state --STATE ESTABLISHED,RELATED -j ACCEPT $IPT -A OUTPUT -m state --STATE ESTABLISHED,RELATED -j ACCEPT # Allow All for SSH # allow ssh connections from outside to inside $IPT -A INPUT -i eth0 -p tcp --dport 22 -j ACCEPT # allow ssh connections from inside to outside $IPT -A OUTPUT -o eth0 -p tcp --dport 22 -j ACCEPT # Allow all for HTTP / HTTPS $IPT -A INPUT -i eth0 -p tcp --dport 80 -j ACCEPT $IPT -A INPUT -i eth0 -p tcp --dport 443 -j ACCEPT # Allow loopback traffic $IPT -A INPUT -i lo -j ACCEPT $IPT -A OUTPUT -o lo -j ACCEPT # Allow to be pinged ( Outside => srv ) $IPT -A INPUT -p icmp --icmp-type echo-request -j ACCEPT $IPT -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT # from srv to outside $IPT -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT $IPT -A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT # Allow outgoing DNS connections $IPT -A OUTPUT -p udp -o eth0 --dport 53 -j ACCEPT # Apt-get $IPT -A OUTPUT -p tcp --dport 80 -j ACCEPT $IPT -A OUTPUT -p tcp --dport 21 -j ACCEPT # SMTP Outgoing $IPT -A OUTPUT -p tcp --dport 25 -j ACCEPT 

我希望这有帮助。 对不起我的英语，不是我的母语。

对于最简单的规则（现在的忽略状态）：

 iptables -A INPUT -p tcp --sport 22 -j ACCEPT iptables -A OUTPUT -p tcp --dport 22 -j ACCEPT 

这应该做的伎俩。 一旦你尝试并成功，你可以修改它包括状态，源/目标IP地址，不同的端口..