发现并识别 IKE 主机（IPsec VPN 服务器）
ike-scan 使用标准的 GNU autoconf 和 automake 工具，因此安装过程如下：
git clone https://github.com/royhills/ike-scan.git 获取项目源码cd ike-scan 进入源码目录autoreconf --install 生成可用的 ./configure 文件./configure 或 ./configure --with-openssl 以使用 OpenSSL 库make 构建项目make check 验证一切正常make install 进行安装（此步骤需要 root 或 sudo 权限）如果你计划进行预共享密钥破解，建议配置 ike-scan 使用 OpenSSL 的哈希函数（而非内置函数），因为 OpenSSL 通常速度更快。为此，请确保已安装 OpenSSL 的头文件和库，并运行 ./configure --with-openssl。是否使用 OpenSSL 不会影响 ike-scan 的功能，仅会影响 psk-crack 进行预共享密钥破解的速度。
某些操作系统默认安装了 OpenSSL 头文件和库；其他系统则需要安装可选软件包，例如在 Debian Linux 上你需要安装 libssl-dev 包。或者，你也可以从 http://www.openssl.org/ 下载并安装 OpenSSL 的 tarball。
该项目应在大多数现代类 Unix 操作系统上构建。在 Windows 上可通过 Cygwin 运行，当存在 cygwin1.dll 时也可作为独立的 Windows 可执行程序使用。
如果你使用的是 Windows-32 二进制包，请同时阅读 README-WIN32 文件，其中详细说明了在 Windows 平台上的差异。
该程序已知可在 Linux、FreeBSD、OpenBSD、NetBSD、Win32/Cygwin、Solaris、MacOS X、HP Tru64、HP-UX 和 SCO OpenServer 上构建并运行。更多详情请参见下方“支持的平台”部分。
ike-scan 能够发现 IKE 主机，并可通过重传后退模式对其进行指纹识别。
ike-scan 可以执行以下功能：
重传后退指纹识别的概念在 UDP 后退指纹识别论文中有更详细的讨论，该论文应包含在 ike-scan 套件中，文件名为 UDP Backoff Fingerprinting Paper。
该程序向指定主机发送 IKE 阶段 1（主模式或积极模式）请求，并显示接收到的任何响应。它处理带有后退的重试和重传，以应对数据包丢失。它还限制了出站 IKE 数据包所使用的带宽。
IKE 是互联网密钥交换协议，是 IPsec 使用的密钥交换和认证机制。几乎所有现代 VPN 系统都实现 IPsec，而绝大多数 IPsec VPN 使用 IKE 进行密钥交换。主模式是 IKE 交换阶段 1 定义的两种模式之一（另一种是积极模式）。RFC 2409 第 5 节规定必须实现主模式，因此所有 IKE 实现都应支持主模式。许多实现也支持积极模式。
要查看当前使用信息，请按如下方式运行 ike-scan 二进制程序：ike-scan -h
Additional documentation is provided on the NTA Monitor Wiki
To report bugs or suggest new features, please create a GitHub issue.
The hosts to scan can be specified on the command line or read from an input file using the --file=<fn> option. The program can cope with large numbers of hosts limited only by the amount of memory needed to store the list of host_entry structures. Each host_entry structure requires 45 bytes on a 32-bit system, so a class B network (65534 hosts) would require about 2.8 MB for the list. The hosts can be specified as either IP addresses or hostnames, however the program will store all hosts internally as IP addresses and will only display IP addresses in the output (ike-scan calls gethostbyname(3) to determine the IP address of each host, but this can be disabled with the --nodns option).
The program limits the rate at which it sends IKE packets to ensure that it does not overload the network connection. By default it uses an outbound data rate of 56000 bits per second. This can be changed with the --bandwidth option.
If you want to send packets at a specific rate, you can use the --interval option.
ike-scan generates unique IKE cookies for each host, and it uses these cookies to determine which host the response packets belong to. Note that it does not rely on the source IP address of the response packets because it is possible for a response packet to be sent from a different IP address than it was originally sent to. See the PROGRAM OUTPUT section for an example of this.
The cookies are generated by taking the first 64 bits of an MD5 hash of the current time in seconds and microseconds as returned by gettimeofday(), the unique host number, and the host IP address. This ensures that the cookies are unique with a reasonable degree of certainty.
If --verbose is in effect, any packets that are received with cookies that do not match will result in a message like:
Ignoring 84 bytes from 172.16.2.2 with unknown cookie 195c837e5a39f657
如果未启用 --verbose，这些数据包将被静默忽略。
此类cookie不匹配可能由以下原因引起：
发送的主模式数据包包含一个 ISAKMP 头部和一个 SA 载荷。SA 载荷包含一个单一提议，并且该提议可以包含可变数量的变换，如下所述。
默认情况下，SA 提议包含 8 个变换。这 8 个变换代表了以下所有可能组合：
以下是使用默认变换集时，ike-scan 发送的主模式数据包的示例 tcpdump 输出。显示了这 8 个变换以及它们的发送顺序：
16:57:16.024536 192.168.124.8.500 > 172.16.2.2.500: [udp sum ok]isakmp 1.0 msgid 00000000: phase 1 I ident:
(sa: doi=ipsec situation=identity
(p: #1 protoid=isakmp transform=8
(t: #1 id=ike (type=enc value=3des)(type=hash value=sha1)(type=auth value=preshared)(type=group desc value=modp1024)(type=lifetype value=sec)(type=lifeduration len=4 value=00007080))
(t: #2 id=ike (type=enc value=3des)(type=hash value=md5)(type=auth value=preshared)(type=group desc value=modp1024)(type=lifetype value=sec)(type=lifeduration len=4 value=00007080))
(t: #3 id=ike (type=enc value=1des)(type=hash value=sha1)(type=auth value=preshared)(type=group desc value=modp1024)(type=lifetype value=sec)(type=lifeduration len=4 value=00007080))
(t: #4 id=ike (type=enc value=1des)(type=hash value=md5)(type=auth value=preshared)(type=group desc value=modp1024)(type=lifetype value=sec)(type=lifeduration len=4 value=00007080))
(t: #5 id=ike (type=enc value=3des)(type=hash value=sha1)(type=auth value=preshared)(type=group desc value=modp768)(type=lifetype value=sec)(type=lifeduration len=4 value=00007080))
(t: #6 id=ike (type=enc value=3des)(type=hash value=md5)(type=auth value=preshared)(type=group desc value=modp768)(type=lifetype value=sec)(type=lifeduration len=4 value=00007080))
(t: #7 id=ike (type=enc value=1des)(type=hash value=sha1)(type=auth value=preshared)(type=group desc value=modp768)(type=lifetype value=sec)(type=lifeduration len=4 value=00007080))
(t: #8 id=ike (type=enc value=1des)(type=hash value=md5)(type=auth value=preshared)(type=group desc value=modp768)(type=lifetype value=sec)(type=lifeduration len=4 value=00007080)))) (DF) (ttl 64, id 0, len 364)```
此默认变换集旨在被大多数 IKE 实现所接受——大多数会接受至少一个提供的变换。然而，有时需要使用不同的身份验证方法（预共享密钥是最常见的，但并非总是支持），偶尔也需要指定不同的密码，例如 256 位 AES。更罕见的情况可能需要更改生命周期。最后，一些实现要求客户端发送特定的“供应商 ID”字符串才能响应。这可以通过 --vendor 选项指定。
默认变换集产生的数据包数据长度为 336 字节，加上 IP 和 UDP 头部后，总数据包大小为 364 字节。
可以使用 --auth 指定身份验证方法（默认为 1 - 预共享密钥），并使用 --lifetime 指定 IKE 生命周期（以秒为单位，默认为 28800 秒或 8 小时，如 RFC 2407 推荐）。如果将 --lifetime 指定为 0，则变换载荷中不包含生命周期属性。如果指定自定义变换，可以多次使用此选项以生成具有不同生命周期的变换载荷。每个 --trans 选项将使用先前指定的生命周期值。
可以使用 --trans=e[/l],h,a,g 指定自定义变换集，其中"e"是加密算法，"l"是可变长度加密算法的密钥长度，"h"是哈希算法，"a"是身份验证方法，"g"是 DH 组。这些都以数值指定；有关使用哪些值的详细信息，请参见 RFC 2409 附录 A。
例如：--trans=5,2,1,2 指定：Enc=5 (3DES-CBC), Hash=2 (SHA1), Auth=1 (shared key), DH Group=2 (modp 1024)
and --trans=7/256,1,1,5 specifies:
Enc=7 (AES), Keylen=256 bits, Hash=MD5, Auth=shared key, DH Group=5 (modp 1536)
您可以在提案中多次使用--trans选项来发送任意数量的自定义转换。
指定自定义转换集将覆盖任何通过--auth指定的认证方法。但是，它仍然使用最后一条--lifetime选项中指定的生存期值。
一个复杂自定义转换集的示例如下：--trans=5,2,1,2 --lifetime=0 --trans=7/256,1,3,5 --lifetime=600 --trans=7/128,1,3,5
This would specify the following three transforms:
If a custom transform set is specified, the packet length will differ from the default. Fewer than 8 transforms will make it smaller, and more than 8 transforms will make it larger. If the packet size exceeds the MTU, then it will be fragmented. You may need to increase the --interval setting for large packets to avoid overloading your network connection. Some VPN servers may ignore very long packets.
A custom transform can be useful in the following situations:
The default mode used is Main Mode. However, it is possible to specify Aggressive Mode with the --aggressive option. When this is done, three additional payloads will be included: Key Exchange, Nonce and ID. This will increase the packet size, and you may need to increase --interval to ensure that ike-scan doesn't try to use too much bandwidth as a result. If you use Aggressive Mode, you can also use the following options:
--id Set identification value.--idtype Set identification type (Default 3 (ID_USER_FQDN)).--dhgroup Specify Diffie-Hellman group (Default 2 - MODP 1024).If you use Aggressive Mode, then you can only use one Diffie Hellman group in the transform set. If you specify custom transforms with the --trans option, you should ensure that they all use the same group, and that this group matches the DH group specified with the --dhgroup option, or the default of 2 if --dhgroup is not specified.
IKE hosts may respond in one of two ways:
An example tcpdump output for a "handshake" response is:
16:57:48.068698 172.16.2.2.500 > 192.168.124.8.500: [udp sum ok]isakmp 1.0 msgid 00000000: phase 1 R ident:
(sa: doi=ipsec situation=identity
(p: #1 protoid=isakmp transform=1
(t: #1 id=ike (type=enc value=3des)(type=hash value=sha1)(type=auth value=preshared)(type=group desc value=modp1024)(type=lifetype value=sec)(type=lifeduration len=4 value=00007080)))) (ttl 126, id 37891, len 112)
This shows that the IKE host has responded with an ISAKMP header and an SA payload containing a single proposal. This proposal contains a single transform representing the transform chosen from the proposal sent by ike-scan.
An example tcpdump output for a "notify" response is:
17:12:55.038554 192.168.89.22.500 > 192.168.37.1.500: [udp sum ok]isakmp 1.0 msgid 00000000: phase 1 R inf:
(n: doi=0 proto=1 type=NO-PROPOSAL-CHOSEN) (ttl 52, id 39577, len 68)
This shows that the IKE host has responded with an ISAKMP header and a notify payload. The notify payload is an informational message with the type "NO-PROPOSAL-CHOSEN".
ike-scan does not respond to any of the IKE responses it receives, so the IKE main mode handshake will never complete. Some IKE implementations do not log handshakes that don't complete; these implementations will not log the scanning and therefore the owners of these systems will not be aware of the scanning. It is possible to use ike-scan to determine if a given implementation will log these scanning attempts if you have access to the system logs.
For those hosts that respond, ike-scan records the times of the received IKE responses. The backoff between IKE responses varies between different IKE implementations and can therefore be used as a fingerprint. The --showbackoff option is used to display the backoff times for each host which responded. Note that using the --showbackoff option will cause ike-scan to wait for 60 seconds after the last received packet to ensure that it has seen all of the responses. This 60 second wait can be altered by specifying a different value in seconds to the --showbackoff option.
When all of the packets have been received, the backoff table is displayed, and the program attempts to match the backoff pattern against the known backoff patterns contained in the text file ike-backoff-patterns. It is possible to add new patterns to this file.
Note that only hosts which respond with a handshake can be fingerprinted by backoff timings; hosts which respond with a notify message cannot. This is because notify messages are only ever sent once and are not subject to retransmission with backoff.
If you discover IKE hosts with backoff patterns which are not recognised by ike-scan, then you are encouraged to submit the pattern and details of the IKE implementation to me so I can incorporate it into future versions of ike-scan. You can do this by opening an issue, or a pull request on github.
Note that any packet loss will prevent the backoff fingerprinting from working because the program needs to see all of the responses.
ike-scan can also be used to fingerprint IKE hosts in other ways. For example:
--sport=0) whereas others (e.g. Windows 2000) only respond to IKE requests from source port 500 (actually, Windows 2000 responds to requests from any port, but always sends the responses back to port 500 which amounts to the same thing).--trans. Note however, that the user can usually change the transform set, so this cannot be relied upon by itself.The program output consists of two sections:
--showbackoff is specified).The IKE host detection section contains one line for each host that responds. The response can either be a successful handshake or an informational message. Only the first packet returned by any given host is displayed in this section.
Some examples of the IKE host detection section are:
10.0.1.98 IKE Handshake returned (1 transforms)
10.0.1.22 Notify message 14 (NO-PROPOSAL-CHOSEN)
10.0.1.189 (10.0.1.130) Notify message 9101 (No common authentication method with Firewall.)
In the above example output, host 10.0.1.98 has returned an IKE handshake, 10.0.1.22 has returned notify message 14 (decimal) which corresponds to the RFC-defined error message "NO-PROPOSAL-CHOSEN" (see RFC 2408 section 3.14.1), and 10.0.1.189 has returned a non-standard notify message 9101 but the response has come from the IP address 10.0.1.130 rather than the address which the request was sent to (presumably this is a multi-homed system). Notify message 9101 is not defined by RFC 2408, but it is known to be a Checkpoint proprietary notify code (therefore the system is probably Firewall-1) and the program displays the text included in the notify message.
Some examples of the IKE backoff pattern section are:
IP Address No. Recv time Delta Time
172.16.2.2 1 1042549209.247980 0.000000
172.16.2.2 2 1042549211.239254 1.991274
172.16.2.2 3 1042549213.241935 2.002681
172.16.2.2 4 1042549215.244731 2.002796
172.16.2.2 5 1042549217.247512 2.002781
172.16.2.2 6 1042549219.250254 2.002742
172.16.2.2 7 1042549221.253044 2.002790
172.16.2.2 8 1042549225.258551 4.005507
172.16.2.2 9 1042549229.264074 4.005523
172.16.2.2 10 1042549233.269605 4.005531
172.16.2.2 11 1042549237.275145 4.005540
172.16.2.2 12 1042549241.280654 4.005509
172.16.2.2 Implementation guess: Firewall-1 4.1/NG
IP Address No. Recv time Delta Time
10.0.1.98 1 1042549209.426540 0.000000
10.0.1.98 2 1042549224.425435 14.998895
10.0.1.98 3 1042549239.422251 14.996816
10.0.1.98 Implementation guess: Cisco IOS / PIX
Here, host 172.16.2.2 returned a total of 12 packets and the pattern matched "Firewall-1 4.1/NG", and host 10.0.1.98 returned 3 packets matching the pattern for "Cisco IOS / PIX". The recv time column shows the absolute time when the packet was received in seconds and microseconds since the epoch; delta time shows the elapsed time between packets in seconds and microseconds.
The below example will run IKE detection against the single host 172.16.2.2. No backoff fingerprinting will be done, and all options (timeouts, retrys, transform set Etc) will be the default.
ike-scan 172.16.2.2This will read the target hosts from the file "hostlist.txt".
ike-scan --file=hostlist.txtThis reads the hosts from stdin and performs both IKE detection and backoff fingerprinting. The backoff wait is specified as 20 seconds.
cat hostlist.txt | ike-scan --file=- --showbackoff=20This will run ike-scan against all hosts in the network specified by 172.16.0.0/16 (including network and broadcast addresses). In this case, this will result in a total of 65536 hosts being scanned - from 172.16.0.0 to 172.16.255.255 inclusive.
ike-scan 172.16.0.0/16This uses the range notation to scan a total of 65536 hosts from 172.16.0.0 to 172.16.255.255 inclusive.
ike-scan 172.16.0.0-172.16.255.255ike-scan has been built and tested on the following platforms:
I've also had reports that it builds OK on the following systems:
It should work, or be capable of working, on any Unix-like system which has a 64-bit integer type, supports sockets and has the system calls malloc, gethostbyname, gettimeofday, inet_ntoa, memset, select, socket, and strerror.
If you port ike-scan to a system not listed above, please let me know the details of the changes required so I can add them to future releases.
For an in-depth coverage of IPsec including IKE, I recommend the book "IPsec The New Security Standard for the Internet, Intranets and Virtual Private Networks" by Doraswamy and Harkins, ISBN 0-13-011898-2. I used this book together with the RFCs to learn about IKE.
The following RFCs relate to IKE:
All of these RFCs can be obtained from: http://www.ietf.org/rfc
The best way to contact me is via the ike-scan repository on github.
I would like to hear from you if you have any of the following:
If you need to contact me offline, please email me at [email protected]