端口扫描 开启 防火墙 iptables SELinux

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Linux 如何打开端口 - lclc - 博客园 https://www.cnblogs.com/lcword/p/5869522.html

linux如何查看端口相关信息_百度经验 https://jingyan.baidu.com/article/fdbd4277fba4dab89e3f48ab.html

[root@bigdata-server-01 sysconfig]# find / | grep iptables
/usr/sbin/iptables-restore
/usr/sbin/iptables
/usr/sbin/iptables-save
/usr/share/doc/iptables-1.4.21
/usr/share/doc/iptables-1.4.21/COPYING
/usr/share/doc/iptables-1.4.21/INCOMPATIBILITIES
/usr/share/man/man1/iptables-xml.1.gz
/usr/share/man/man8/iptables.8.gz
/usr/share/man/man8/iptables-extensions.8.gz
/usr/share/man/man8/iptables-restore.8.gz
/usr/share/man/man8/iptables-save.8.gz
/usr/share/mime/text/x-iptables.xml
/usr/bin/iptables-xml
/etc/sysconfig/iptables-config
/etc/selinux/targeted/active/modules/100/iptables
/etc/selinux/targeted/active/modules/100/iptables/hll
/etc/selinux/targeted/active/modules/100/iptables/cil
/etc/selinux/targeted/active/modules/100/iptables/lang_ext
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/from_repo
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/checksum_data
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/origin_url
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/var_uuid
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/changed_by
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/var_infra
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/from_repo_revision
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/checksum_type
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/reason
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/command_line
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/from_repo_timestamp
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/installed_by
/var/lib/yum/yumdb/i/b65e29d0ee30309c2cf4ba3ab0cce299f698651c-iptables-1.4.21-18.2.el7_4-x86_64/releasever
[root@bigdata-server-01 sysconfig]#

service iptables start/stop

安装

解决CentOS7关闭/开启防火墙出现Unit iptables.service failed to load: No such file or directory. - CSDN博客 http://blog.csdn.net/c233728461/article/details/52679558

# yum install iptables

[root@bigdata-server-01 sysconfig]# systemctl enable iptables
Created symlink from /etc/systemd/system/basic.target.wants/iptables.service to /usr/lib/systemd/system/iptables.service.
[root@bigdata-server-01 sysconfig]# vim /etc/sysconfig/iptables

# sample configuration for iptables service
# you can edit this manually or use system-config-firewall
# please do not ask us to add additional ports/services to this default configuration
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT

:set nu

: 11,11 copy 11

复制已有的22端口行，改为5000，为flask准备

重启

iptables

systemctl restart iptables

[root@hadoop3 ~]# find / | grep iptables
/home/data/xl_tmp/C/Users/Administrator.PC-201707311140/Desktop/desk/manual-master.tar/html/tutorial/configure-linux-iptables-firewall.html
/home/data/xl_tmp/C/Users/Administrator.PC-201707311140/Desktop/manual-master.tar/html/tutorial/configure-linux-iptables-firewall.html
/etc/sysconfig/iptables-config
/etc/sysconfig/iptables
/etc/selinux/targeted/modules/active/modules/iptables.pp
/var/lib/yum/yumdb/i/fb1ea5f54bb511b515a25d6b6de76a796fcf68b2-iptables-1.4.21-16.el7-x86_64
/var/lib/yum/yumdb/i/fb1ea5f54bb511b515a25d6b6de76a796fcf68b2-iptables-1.4.21-16.el7-x86_64/from_repo
/var/lib/yum/yumdb/i/fb1ea5f54bb511b515a25d6b6de76a796fcf68b2-iptables-1.4.21-16.el7-x86_64/reason
/var/lib/yum/yumdb/i/fb1ea5f54bb511b515a25d6b6de76a796fcf68b2-iptables-1.4.21-16.el7-x86_64/releasever
/var/lib/yum/yumdb/i/fb1ea5f54bb511b515a25d6b6de76a796fcf68b2-iptables-1.4.21-16.el7-x86_64/var_uuid
/var/lib/yum/yumdb/i/fb1ea5f54bb511b515a25d6b6de76a796fcf68b2-iptables-1.4.21-16.el7-x86_64/checksum_type
/var/lib/yum/yumdb/i/fb1ea5f54bb511b515a25d6b6de76a796fcf68b2-iptables-1.4.21-16.el7-x86_64/checksum_data
/var/lib/yum/yumdb/i/fb1ea5f54bb511b515a25d6b6de76a796fcf68b2-iptables-1.4.21-16.el7-x86_64/from_repo_revision
/var/lib/yum/yumdb/i/fb1ea5f54bb511b515a25d6b6de76a796fcf68b2-iptables-1.4.21-16.el7-x86_64/from_repo_timestamp
/var/lib/yum/yumdb/i/fb1ea5f54bb511b515a25d6b6de76a796fcf68b2-iptables-1.4.21-16.el7-x86_64/installed_by
/usr/bin/iptables-xml
/usr/sbin/iptables
/usr/sbin/iptables-restore
/usr/sbin/iptables-save
/usr/share/doc/iptables-1.4.21
/usr/share/doc/iptables-1.4.21/COPYING
/usr/share/doc/iptables-1.4.21/INCOMPATIBILITIES
/usr/share/man/man1/iptables-xml.1.gz
/usr/share/man/man8/iptables-extensions.8.gz
/usr/share/man/man8/iptables-restore.8.gz
/usr/share/man/man8/iptables-save.8.gz
/usr/share/man/man8/iptables.8.gz
/usr/share/mime/text/x-iptables.xml
[root@hadoop3 ~]#

https://www.howtogeek.com/177621/the-beginners-guide-to-iptables-the-linux-firewall/

iptables is a command-line firewall utility that uses policy chains to allow or block traffic. When a connection tries to establish itself on your system, iptables looks for a rule in its list to match it to. If it doesn’t find one, it resorts to the default action.

iptables almost always comes pre-installed on any Linux distribution. To update/install it, just retrieve the iptables package:

There are GUI alternatives to iptables like Firestarter, but iptables isn’t really that hard once you have a few commands down. You want to be extremely careful when configuring iptables rules, particularly if you’re SSH’d into a server, because one wrong command can permanently lock you out until it’s manually fixed at the physical machine.

Types of Chains

iptables uses three different chains: input, forward, and output.

Input – This chain is used to control the behavior for incoming connections. For example, if a user attempts to SSH into your PC/server, iptables will attempt to match the IP address and port to a rule in the input chain.

Forward – This chain is used for incoming connections that aren’t actually being delivered locally. Think of a router – data is always being sent to it but rarely actually destined for the router itself; the data is just forwarded to its target. Unless you’re doing some kind of routing, NATing, or something else on your system that requires forwarding, you won’t even use this chain.

There’s one sure-fire way to check whether or not your system uses/needs the forward chain.

[root@hadoop3 ~]# /usr/sbin/iptables -h
iptables v1.4.21

Usage: iptables -[ACD] chain rule-specification [options]
iptables -I chain [rulenum] rule-specification [options]
iptables -R chain rulenum rule-specification [options]
iptables -D chain rulenum [options]
iptables -[LS] [chain [rulenum]] [options]
iptables -[FZ] [chain] [options]
iptables -[NX] chain
iptables -E old-chain-name new-chain-name
iptables -P chain target [options]
iptables -h (print this help information)

Commands:
Either long or short options are allowed.
--append -A chainAppend to chain
--check -C chainCheck for the existence of a rule
--delete -D chainDelete matching rule from chain
--delete -D chain rulenum
Delete rule rulenum (1 = first) from chain
--insert -I chain [rulenum]
Insert in chain as rulenum (default 1=first)
--replace -R chain rulenum
Replace rule rulenum (1 = first) in chain
--list -L [chain [rulenum]]
List the rules in a chain or all chains
--list-rules -S [chain [rulenum]]
Print the rules in a chain or all chains
--flush -F [chain]Delete all rules in chain or all chains
--zero -Z [chain [rulenum]]
Zero counters in chain or all chains
--new -N chainCreate a new user-defined chain
--delete-chain
-X [chain]Delete a user-defined chain
--policy -P chain target
Change policy on chain to target
--rename-chain
-E old-chain new-chain
Change chain name, (moving any references)
Options:
--ipv4-4Nothing (line is ignored by ip6tables-restore)
--ipv6-6Error (line is ignored by iptables-restore)
[!] --protocol-p protoprotocol: by number or name, eg. `tcp'
[!] --source-s address[/mask][...]
source specification
[!] --destination -d address[/mask][...]
destination specification
[!] --in-interface -i input name[+]
network interface name ([+] for wildcard)
--jump-j target
target for rule (may load target extension)
--goto -g chain
jump to chain with no return
--match-m match
extended match (may load extension)
--numeric-nnumeric output of addresses and ports
[!] --out-interface -o output name[+]
network interface name ([+] for wildcard)
--table-t tabletable to manipulate (default: `filter')
--verbose-vverbose mode
--wait-w [seconds]wait for the xtables lock
--line-numbersprint line numbers when listing
--exact-xexpand numbers (display exact values)
[!] --fragment-fmatch second or further fragments only
--modprobe=<command>try to insert modules using this command
--set-counters PKTS BYTESset the counter during insert/append
[!] --version-Vprint package version.
[root@hadoop3 ~]#

The screenshot above is of a server that’s been running for a few weeks and has no restrictions on incoming or outgoing connections. As you can see, the input chain has processed 11GB of packets and the output chain has processed 17GB. The forward chain, on the other hand, has not needed to process a single packet. This is because the server isn’t doing any kind of forwarding or being used as a pass-through device.

Output – This chain is used for outgoing connections. For example, if you try to ping howtogeek.com, iptables will check its output chain to see what the rules are regarding ping and howtogeek.com before making a decision to allow or deny the connection attempt.

The caveat

Even though pinging an external host seems like something that would only need to traverse the output chain, keep in mind that to return the data, the input chain will be used as well. When using iptables to lock down your system, remember that a lot of protocols will require two-way communication, so both the input and output chains will need to be configured properly. SSH is a common protocol that people forget to allow on both chains.

Policy Chain Default Behavior

Before going in and configuring specific rules, you’ll want to decide what you want the default behavior of the three chains to be. In other words, what do you want iptables to do if the connection doesn’t match any existing rules?

To see what your policy chains are currently configured to do with unmatched traffic, run the iptables -L command.

As you can see, we also used the grep command to give us cleaner output. In that screenshot, our chains are currently figured to accept traffic.

More times than not, you’ll want your system to accept connections by default. Unless you’ve changed the policy chain rules previously, this setting should already be configured. Either way, here’s the command to accept connections by default:

iptables --policy INPUT ACCEPT
iptables --policy OUTPUT ACCEPT
iptables --policy FORWARD ACCEPT

By defaulting to the accept rule, you can then use iptables to deny specific IP addresses or port numbers, while continuing to accept all other connections. We’ll get to those commands in a minute.

If you would rather deny all connections and manually specify which ones you want to allow to connect, you should change the default policy of your chains to drop. Doing this would probably only be useful for servers that contain sensitive information and only ever have the same IP addresses connect to them.

iptables --policy INPUT DROP
iptables --policy OUTPUT DROP
iptables --policy FORWARD DROP

Connection-specific Responses

With your default chain policies configured, you can start adding rules to iptables so it knows what to do when it encounters a connection from or to a particular IP address or port. In this guide, we’re going to go over the three most basic and commonly used “responses”.

Accept – Allow the connection.

Drop – Drop the connection, act like it never happened. This is best if you don’t want the source to realize your system exists.

Reject – Don’t allow the connection, but send back an error. This is best if you don’t want a particular source to connect to your system, but you want them to know that your firewall blocked them.

The best way to show the difference between these three rules is to show what it looks like when a PC tries to ping a Linux machine with iptables configured for each one of these settings.

Allowing the connection:

Dropping the connection:

Rejecting the connection:

Allowing or Blocking Specific Connections

With your policy chains configured, you can now configure iptables to allow or block specific addresses, address ranges, and ports. In these examples, we’ll set the connections to DROP, but you can switch them to ACCEPT or REJECT, depending on your needs and how you configured your policy chains.

Note: In these examples, we’re going to use iptables -A to append rules to the existing chain. iptables starts at the top of its list and goes through each rule until it finds one that it matches. If you need to insert a rule above another, you can use iptables -I [chain] [number] to specify the number it should be in the list.

Connections from a single IP address

This example shows how to block all connections from the IP address 10.10.10.10.

iptables -A INPUT -s 10.10.10.10 -j DROP

Connections from a range of IP addresses

This example shows how to block all of the IP addresses in the 10.10.10.0/24 network range. You can use a netmask or standard slash notation to specify the range of IP addresses.

iptables -A INPUT -s 10.10.10.0/24 -j DROP

or

iptables -A INPUT -s 10.10.10.0/255.255.255.0 -j DROP

Connections to a specific port

This example shows how to block SSH connections from 10.10.10.10.

iptables -A INPUT -p tcp --dport ssh -s 10.10.10.10 -j DROP

You can replace “ssh” with any protocol or port number. The -p tcp part of the code tells iptables what kind of connection the protocol uses.  If you were blocking a protocol that uses UDP rather than TCP, then -p udp would be necessary instead.

This example shows how to block SSH connections from any IP address.

iptables -A INPUT -p tcp --dport ssh -j DROP

Connection States

As we mentioned earlier, a lot of protocols are going to require two-way communication. For example, if you want to allow SSH connections to your system, the input and output chains are going to need a rule added to them. But, what if you only want SSH coming into your system to be allowed? Won’t adding a rule to the output chain also allow outgoing SSH attempts?

That’s where connection states come in, which give you the capability you’d need to allow two way communication but only allow one way connections to be established. Take a look at this example, where SSH connections FROM 10.10.10.10 are permitted, but SSH connections TO 10.10.10.10 are not. However, the system is permitted to send back information over SSH as long as the session has already been established, which makes SSH communication possible between these two hosts.

iptables -A INPUT -p tcp --dport ssh -s 10.10.10.10 -m state --state NEW,ESTABLISHED -j ACCEPT

iptables -A OUTPUT -p tcp --sport 22 -d 10.10.10.10 -m state --state ESTABLISHED -j ACCEPT

Saving Changes

The changes that you make to your iptables rules will be scrapped the next time that the iptables service gets restarted unless you execute a command to save the changes.  This command can differ depending on your distribution:

Ubuntu:

sudo /sbin/iptables-save

Red Hat / CentOS:

/sbin/service iptables save

Or

/etc/init.d/iptables save

Other Commands

List the currently configured iptables rules:

iptables -L

Adding the -v option will give you packet and byte information, and adding -n will list everything numerically. In other words – hostnames, protocols, and networks are listed as numbers.

To clear all the currently configured rules, you can issue the flush command.

iptables -F

windows 打开关闭防火墙 对比

C:\Users\sas>ping 192.168.2.160

正在 Ping 192.168.2.160 具有 32 字节的数据:
请求超时。
请求超时。
请求超时。
请求超时。

192.168.2.160 的 Ping 统计信息:
数据包: 已发送 = 4，已接收 = 0，丢失 = 4 (100% 丢失)，

C:\Users\sas>ping 192.168.2.160

正在 Ping 192.168.2.160 具有 32 字节的数据:
来自 192.168.2.160 的回复: 字节=32 时间=1ms TTL=128
来自 192.168.2.160 的回复: 字节=32 时间<1ms TTL=128
来自 192.168.2.160 的回复: 字节=32 时间<1ms TTL=128
来自 192.168.2.160 的回复: 字节=32 时间<1ms TTL=128

192.168.2.160 的 Ping 统计信息:
数据包: 已发送 = 4，已接收 = 4，丢失 = 0 (0% 丢失)，
往返行程的估计时间(以毫秒为单位):
最短 = 0ms，最长 = 1ms，平均 = 0ms

防火墙已经关闭

但是仍然

逐条检查

启用对远程服务器的访问
https://jingyan.baidu.com/album/8065f87f816f5323312498a1.html?picindex=5

注册表检查

打开注册表

C:\Windows\regedit.exe

计算机\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server

AllowRemoteRPC  设为1 允许

计算机\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp

检测端口是否被占用  netstat -at

设置3389为远程连接端口

PortNumber  d3d   16进制  3389 =13+3*16+13*256 = 3328+61

SELinux_百度百科 https://baike.baidu.com/item/SELinux/8865268?fr=aladdin

【进程只能访问那些在他的任务中所需要文件】