我有以下情况：
Internet ----- Server ------- virtual machine (kvm)
public ip 192.168.122.12
x.x.x.x
我需要使虚拟机上的 3333 端口上的服务可从互联网访问。
可以从服务器访问服务 3333。我使用以下命令对其进行了测试：
nc -v -w 5 192.168.122.12 3333;echo $?
我收到 Ncat：已连接到 192.68.122.201:3333
我尝试过这个设置
iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 3333 -j DNAT --to 192.168.122.12:3333
iptables -A FORWARD -p tcp -d 192.168.122.12 --dport 3333 -j ACCEPT
但仍然无法通过互联网访问服务。您能帮助我吗？
服务器和虚拟机都可以访问互联网。当我只使用：
socat TCP-LISTEN:3333,fork TCP:192.168.122.12:3333
并在服务器上启用 3333，一切正常。
是否可以使用 iptables 来实现？问题可能出在哪里？
更新 1 我的普通 iptables：
iptables -t nat -L -n -v
Chain PREROUTING (policy ACCEPT 20 packets, 1750 bytes)
pkts bytes target prot opt in out source destination
21 1828 PREROUTING_direct all -- * * 0.0.0.0/0 0.0.0.0/0
21 1828 PREROUTING_ZONES_SOURCE all -- * * 0.0.0.0/0 0.0.0.0/0
21 1828 PREROUTING_ZONES all -- * * 0.0.0.0/0 0.0.0.0/0
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 4 packets, 240 bytes)
pkts bytes target prot opt in out source destination
4 240 OUTPUT_direct all -- * * 0.0.0.0/0 0.0.0.0/0
Chain POSTROUTING (policy ACCEPT 4 packets, 240 bytes)
pkts bytes target prot opt in out source destination
0 0 RETURN all -- * * 192.168.122.0/24 224.0.0.0/24
0 0 RETURN all -- * * 192.168.122.0/24 255.255.255.255
5 260 MASQUERADE tcp -- * * 192.168.122.0/24 !192.168.122.0/24 masq ports: 1024-65535
0 0 MASQUERADE udp -- * * 192.168.122.0/24 !192.168.122.0/24 masq ports: 1024-65535
0 0 MASQUERADE all -- * * 192.168.122.0/24 !192.168.122.0/24
4 240 POSTROUTING_direct all -- * * 0.0.0.0/0 0.0.0.0/0
4 240 POSTROUTING_ZONES_SOURCE all -- * * 0.0.0.0/0 0.0.0.0/0
4 240 POSTROUTING_ZONES all -- * * 0.0.0.0/0 0.0.0.0/0
Chain OUTPUT_direct (1 references)
pkts bytes target prot opt in out source destination
Chain POSTROUTING_ZONES (1 references)
pkts bytes target prot opt in out source destination
0 0 POST_public all -- * eth0 0.0.0.0/0 0.0.0.0/0 [goto]
4 240 POST_public all -- * + 0.0.0.0/0 0.0.0.0/0 [goto]
Chain POSTROUTING_ZONES_SOURCE (1 references)
pkts bytes target prot opt in out source destination
Chain POSTROUTING_direct (1 references)
pkts bytes target prot opt in out source destination
Chain POST_public (2 references)
pkts bytes target prot opt in out source destination
4 240 POST_public_log all -- * * 0.0.0.0/0 0.0.0.0/0
4 240 POST_public_deny all -- * * 0.0.0.0/0 0.0.0.0/0
4 240 POST_public_allow all -- * * 0.0.0.0/0 0.0.0.0/0
Chain POST_public_allow (1 references)
pkts bytes target prot opt in out source destination
Chain POST_public_deny (1 references)
pkts bytes target prot opt in out source destination
Chain POST_public_log (1 references)
pkts bytes target prot opt in out source destination
Chain PREROUTING_ZONES (1 references)
pkts bytes target prot opt in out source destination
16 1568 PRE_public all -- eth0 * 0.0.0.0/0 0.0.0.0/0 [goto]
5 260 PRE_public all -- + * 0.0.0.0/0 0.0.0.0/0 [goto]
Chain PREROUTING_ZONES_SOURCE (1 references)
pkts bytes target prot opt in out source destination
Chain PREROUTING_direct (1 references)
pkts bytes target prot opt in out source destination
Chain PRE_public (2 references)
pkts bytes target prot opt in out source destination
21 1828 PRE_public_log all -- * * 0.0.0.0/0 0.0.0.0/0
21 1828 PRE_public_deny all -- * * 0.0.0.0/0 0.0.0.0/0
21 1828 PRE_public_allow all -- * * 0.0.0.0/0 0.0.0.0/0
Chain PRE_public_allow (1 references)
pkts bytes target prot opt in out source destination
Chain PRE_public_deny (1 references)
pkts bytes target prot opt in out source destination
Chain PRE_public_log (1 references)
pkts bytes target prot opt in out source destination
iptables -L -n -v
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 ACCEPT udp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:53
0 0 ACCEPT tcp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:53
0 0 ACCEPT udp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 udp dpt:67
0 0 ACCEPT tcp -- virbr0 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:67
1125 688K ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 ctstate RELATED,ESTABLISHED
5 300 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
1 238 INPUT_direct all -- * * 0.0.0.0/0 0.0.0.0/0
1 238 INPUT_ZONES_SOURCE all -- * * 0.0.0.0/0 0.0.0.0/0
1 238 INPUT_ZONES all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
1 238 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
45 4548 ACCEPT all -- * virbr0 0.0.0.0/0 192.168.122.0/24 ctstate RELATED,ESTABLISHED
52 13611 ACCEPT all -- virbr0 * 192.168.122.0/24 0.0.0.0/0
0 0 ACCEPT all -- virbr0 virbr0 0.0.0.0/0 0.0.0.0/0
0 0 REJECT all -- * virbr0 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
0 0 REJECT all -- virbr0 * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
2 113 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 ctstate RELATED,ESTABLISHED
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
0 0 FORWARD_direct all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 FORWARD_IN_ZONES_SOURCE all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 FORWARD_IN_ZONES all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 FORWARD_OUT_ZONES_SOURCE all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 FORWARD_OUT_ZONES all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT 1049 packets, 1272K bytes)
pkts bytes target prot opt in out source destination
0 0 ACCEPT udp -- * virbr0 0.0.0.0/0 0.0.0.0/0 udp dpt:68
1049 1272K OUTPUT_direct all -- * * 0.0.0.0/0 0.0.0.0/0
Chain FORWARD_IN_ZONES (1 references)
pkts bytes target prot opt in out source destination
0 0 FWDI_public all -- eth0 * 0.0.0.0/0 0.0.0.0/0 [goto]
0 0 FWDI_public all -- + * 0.0.0.0/0 0.0.0.0/0 [goto]
Chain FORWARD_IN_ZONES_SOURCE (1 references)
pkts bytes target prot opt in out source destination
Chain FORWARD_OUT_ZONES (1 references)
pkts bytes target prot opt in out source destination
0 0 FWDO_public all -- * eth0 0.0.0.0/0 0.0.0.0/0 [goto]
0 0 FWDO_public all -- * + 0.0.0.0/0 0.0.0.0/0 [goto]
Chain FORWARD_OUT_ZONES_SOURCE (1 references)
pkts bytes target prot opt in out source destination
Chain FORWARD_direct (1 references)
pkts bytes target prot opt in out source destination
Chain FWDI_public (2 references)
pkts bytes target prot opt in out source destination
0 0 FWDI_public_log all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 FWDI_public_deny all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 FWDI_public_allow all -- * * 0.0.0.0/0 0.0.0.0/0
Chain FWDI_public_allow (1 references)
pkts bytes target prot opt in out source destination
Chain FWDI_public_deny (1 references)
pkts bytes target prot opt in out source destination
Chain FWDI_public_log (1 references)
pkts bytes target prot opt in out source destination
Chain FWDO_public (2 references)
pkts bytes target prot opt in out source destination
0 0 FWDO_public_log all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 FWDO_public_deny all -- * * 0.0.0.0/0 0.0.0.0/0
0 0 FWDO_public_allow all -- * * 0.0.0.0/0 0.0.0.0/0
Chain FWDO_public_allow (1 references)
pkts bytes target prot opt in out source destination
Chain FWDO_public_deny (1 references)
pkts bytes target prot opt in out source destination
Chain FWDO_public_log (1 references)
pkts bytes target prot opt in out source destination
Chain INPUT_ZONES (1 references)
pkts bytes target prot opt in out source destination
1 238 IN_public all -- eth0 * 0.0.0.0/0 0.0.0.0/0 [goto]
0 0 IN_public all -- + * 0.0.0.0/0 0.0.0.0/0 [goto]
Chain INPUT_ZONES_SOURCE (1 references)
pkts bytes target prot opt in out source destination
Chain INPUT_direct (1 references)
pkts bytes target prot opt in out source destination
Chain IN_public (2 references)
pkts bytes target prot opt in out source destination
1 238 IN_public_log all -- * * 0.0.0.0/0 0.0.0.0/0
1 238 IN_public_deny all -- * * 0.0.0.0/0 0.0.0.0/0
1 238 IN_public_allow all -- * * 0.0.0.0/0 0.0.0.0/0
Chain IN_public_allow (1 references)
pkts bytes target prot opt in out source destination
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 ctstate NEW
Chain IN_public_deny (1 references)
pkts bytes target prot opt in out source destination
Chain IN_public_log (1 references)
pkts bytes target prot opt in out source destination
Chain OUTPUT_direct (1 references)
pkts bytes target prot opt in out source destination
答案1
编辑文件/etc/sysctl.conf
net.ipv4.ip_forward = 0
重新加载sysctl -p /etc/sysctl.conf
当你访问互联网时，将你的私有 IP 伪装成你的公共 IP（无论哪个接口拥有公共 IP）
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
将传入请求 Nat 回您的 VM 和端口 - 大概是桥接器或分接设备。
iptables -t nat -A PREROUTING -i virbr0 -p tcp --dport 3333 -j DNAT \
--to 192.168.122.12:3333
不要把它掉在外面
iptables -A FORWARD -i virbr0 -p tcp --dport 3333 -d 192.168.122.12 -j ACCEPT