Linux：iptables防火墙部署优化之连接转移（目的地地址转化）

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Linux：iptables防火墙部署优化之连接转移（目的地地址转化）

node1操作

检测ip情况

bash 复制代码

#查看网卡的ip信息
[root@node1 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:33:49:40 brd ff:ff:ff:ff:ff:ff
    altname enp3s0
    altname ens160
    inet 172.25.254.200/24 brd 172.25.254.255 scope global noprefixroute eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::fa94:b632:5bd6:a146/64 scope link noprefixroute
       valid_lft forever preferred_lft forever
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:33:49:4a brd ff:ff:ff:ff:ff:ff
    altname enp19s0
    altname ens224
    inet 192.168.0.100/24 brd 192.168.0.255 scope global noprefixroute eth1
       valid_lft forever preferred_lft forever
    inet6 fe80::518f:2870:1a4c:178f/64 scope link noprefixroute
       valid_lft forever preferred_lft forever

关闭firewalld防火墙服务，并锁定该服务

bash 复制代码

[root@node1 ~]# systemctl disable --now firewalld.service
Removed "/etc/systemd/system/multi-user.target.wants/firewalld.service".
Removed "/etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service".

# 锁定firewalld服务
[root@node1 ~]# systemctl mask firewalld.service
Created symlink /etc/systemd/system/firewalld.service → /dev/null.

开启iptables服务

bash 复制代码

[root@node1 ~]# systemctl enable --now iptables.service
Created symlink /etc/systemd/system/multi-user.target.wants/iptables.service → /usr/lib/systemd/system/iptables.service.

清空iptables的默认策略

bash 复制代码

[root@node1 ~]# iptables -F
[root@node1 ~]# iptables -nL
Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

开启内核路由转发功能

bash 复制代码

# 发现内核路由转发功能未开启
[root@node1 ~]# sysctl -a | grep ip_forward
net.ipv4.ip_forward = 0
net.ipv4.ip_forward_update_priority = 1
net.ipv4.ip_forward_use_pmtu = 0

# 修改配置文件，开启内核路由转发功能
[root@node1 ~]# vim /etc/sysctl.conf
[root@node1 ~]# sysctl -p
net.ipv4.ip_forward = 1

[root@node1 ~]# sysctl -a | grep ip_forward
net.ipv4.ip_forward = 1
net.ipv4.ip_forward_update_priority = 1
net.ipv4.ip_forward_use_pmtu = 0

配置iptables的策略，实现连接转移（目的地地址转换）

bash 复制代码

[root@server100 ~]# iptables -t nat -A PREROUTING -i eth0 -j DNAT --to-dest 192.168.0.200

[root@server100 ~]# iptables -t nat -L
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
DNAT       all  --  anywhere             anywhere             to:192.168.0.200

Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination

node2测试，是否可以登录转移

bash 复制代码

ssh root@172.25.254.100
Warning: Permanently added '172.25.254.100' (ED25519) to the list of known hosts.
root@172.25.254.100's password:
Activate the web console with: systemctl enable --now cockpit.socket

Register this system with Red Hat Insights: insights-client --register
Create an account or view all your systems at https://red.ht/insights-dashboard
Last login: Thu May 16 20:09:18 2024 from 192.168.0.1
[root@node2 ~]#
[root@node2 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:8c:36:ce brd ff:ff:ff:ff:ff:ff
    altname enp3s0
    altname ens160
    inet 192.168.0.200/24 brd 192.168.0.255 scope global noprefixroute eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::261:1a18:738d:cacb/64 scope link noprefixroute
       valid_lft forever preferred_lft forever

这里原来是登录到node1主机，但是却登录到了node2主机