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前 言 UNIX下的杀毒软件有好多是商业版本的。但和windows系统下一样，杀毒软件的质量决定于病毒库的量已及更新的速度。在这里，我们使用自由软件 Clam AntiVirus 来建立linux下的病毒查杀系统。并且为了消除后来的隐患，建议务必在服务器公开以前构建病毒查杀系统。 安装 Clam AntiVirus 由于Clam Antivirus不存在于centos中yum的官方库中，所以用yum安装Clam Antivirus需要定义非官方的库。请先确认相应非官方库文件的存在。 [root@sample ~]# ls -l /etc/yum.repos.d/dag.repo ← 确认相应库文件的存在性 -rw-r--r-- 1 root root 143 Oct 1 21:33 /etc/yum.repos.d/dag.repo ← 确认其存在（否则不能通过yum安装Clamd）如果以上，dag.repo文件不存在，则不能通过yum安装Clam Antivirus，需要定义非官方库。定义非官方库的方法请见 “CentOS的下载、安装及初始环境设置”一节中yum的相关设置。而且，在此前提下也要保证所定义的dag.repo文件的语法的正确性。 然后，通过yum来在线安装 Clam Antivirus 。 [root@sample ~]# yum -y install clamd ← 在线安装 Clam AntiVirus Setting up Install Process Setting up repositories dag 100% |=========================| 1.1 kB 00:00 update 100% |=========================| 951 B 00:00 base 100% |=========================| 1.1 kB 00:00 addons 100% |=========================| 951 B 00:00 extras 100% |=========================| 1.1 kB 00:00 Reading repository metadata in from local files primary.xml.gz 100% |=========================| 1.6 MB 00:08 dag : ################################################## 4610/4610 Added 4610 new packages, deleted 0 old in 94.91 seconds primary.xml.gz 100% |=========================| 103 kB 00:05 update : ################################################## 256/256 Added 56 new packages, deleted 0 old in 4.25 seconds Reducing Dag RPM Repository for Red Hat Enterprise Linux to included packages only Finished Parsing package install arguments Resolving Dependencies --> Populating transaction set with selected packages. Please wait. ---> Downloading header for clamd to pack into transaction set. clamd-0.88.4-1.el4.rf.i38 100% |=========================| 5.3 kB 00:00 ---> Package clamd.i386 0:0.88.4-1.el4.rf set to be updated --> Running transaction check --> Processing Dependency: clamav = 0.88.4-1.el4.rf for package: clamd --> Processing Dependency: libclamav.so.1 for package: clamd --> Restarting Dependency Resolution with new changes. --> Populating transaction set with selected packages. Please wait. ---> Downloading header for clamav to pack into transaction set. clamav-0.88.4-1.el4.rf.i3 100% |=========================| 8.1 kB 00:00 ---> Package clamav.i386 0:0.88.4-1.el4.rf set to be updated --> Running transaction check --> Processing Dependency: clamav-db = 0.88.4-1.el4.rf for package: clamav --> Restarting Dependency Resolution with new changes. --> Populating transaction set with selected packages. Please wait. ---> Downloading header for clamav-db to pack into transaction set. clamav-db-0.88.4-1.el4.rf 100% |=========================| 3.2 kB 00:00 ---> Package clamav-db.i386 0:0.88.4-1.el4.rf set to be updated --> Running transaction check Dependencies Resolved ============================================================================= Package Arch Version Repository Size ============================================================================= Installing: clamd i386 0.88.4-1.el4.rf dag 64 k Installing for dependencies: clamav i386 0.88.4-1.el4.rf dag 724 k clamav-db i386 0.88.4-1.el4.rf dag 5.6 M Transaction Summary ============================================================================= Install 3 Package(s) Update 0 Package(s) Remove 0 Package(s) Total download size: 6.4 M Downloading Packages: (1/3): clamd-0.88.4-1.el4 100% |=========================| 64 kB 00:01 (2/3): clamav-0.88.4-1.el 100% |=========================| 724 kB 00:04 (3/3): clamav-db-0.88.4-1 100% |=========================| 5.6 MB 00:25 Running Transaction Test Finished Transaction Test Transaction Test Succeeded Running Transaction Installing: clamav-db ######################### [1/3] Installing: clamav ######################### [2/3] Installing: clamd ######################### [3/3] Installed: clamd.i386 0:0.88.4-1.el4.rf Dependency Installed: clamav.i386 0:0.88.4-1.el4.rf clamav-db.i386 0:0.88.4-1.el4.rf Complete! ← 安装完毕！ 配置 Clam AntiVirus 接下来配置 Clam Antivirus 。 [root@sample ~]# vi /etc/clamd.conf ← 修改clamd的配置文件 ArchiveBlockMax ← 找到这一行，在行首加上“#”（不把大容量的压缩文件看作被感染病毒的文件） ↓ #ArchiveBlockMax ← 变为此状态 User clamav ← 找到这一行，在行首加上“#”（不允许一般用户控制） ↓ #User clamav ← 变为此状态 运行 Clam AntiVirus 让 Clam Antivirus 开始运行，并设置其为自启动。 [root@sample ~]# chkconfig clamd on ← 将其设置为自系统启动后启动 [root@sample ~]# chkconfig --list clamd clamd 0:off 1:off 2:on 3:on 4:on 5:on 6:off ← 确认2--5为on的状态就OK [root@sample ~]# /etc/rc.d/init.d/clamd start ← 启动clamd服务（运行Clam AntiVirus） Starting Clam AntiVirus Daemon: [ OK ] ← 启动成功 更新 Clam AntiVirus 的病毒库 安装后建议立即更新病毒库，以保证最新病毒的查杀。 [root@sample ~]# freshclam ← 更新clam的病毒库 ClamAV update process started at Fri Aug 25 18:39:26 2006 Downloading main.cvd [*] main.cvd updated (version: 40, sigs: 64138, f-level: 8, builder: tkojm) Downloading daily.cvd [*] daily.cvd updated (version: 1728, sigs: 2565, f-level: 8, builder: ccordes) Database updated (66703 signatures) from db.cn.clamav.net (IP: 58.221.253.171) Clamd successfully notified about the update. 病毒扫描 然后进行病毒扫描的测试，在这里，我们首先下载测试用的病毒文件。 [root@sample ~]# clamdscan ← 进行病毒扫描 /root: OK ----------- SCAN SUMMARY ----------- Infected files: 0 ← 没有发现病毒 Time: 5.074 sec (0 m 5 s) [root@sample ~]# wget http://www.eicar.org/download/eicar.com ← 下载带毒文件 [root@sample ~]# wget http://www.eicar.org/download/eicar_com.zip ← 下载带毒文件 然后，再次进行病毒到描。附加“remove”选项后，会在查出病毒后自动删除染毒文件。 [root@sample ~]# clamdscan --remove ← 再次进行病毒扫描，并附加删除选项 /root/eicar.com: Eicar-Test-Signature FOUND ← 发现被病毒感染的文件 /root/eicar.com: Removed. ← 删除被病毒感染的文件 /root/eicar_com.zip: Eicar-Test-Signature FOUND ← 发现被病毒感染的文件 /root/eicar_com.zip: Removed. ← 删除被病毒感染的文件 ----------- SCAN SUMMARY ----------- Infected files: 2 Time: 2.201 sec (0 m 2 s) 让病毒扫描定期运行 [root@sample ~]# vi scan.sh ← 建立自动扫描脚本，如下： #!/bin/bash PATH=/usr/bin:/bin CLAMSCANTMP=`mktemp` clamdscan --recursive --remove / > $CLAMSCANTMP [ ! -z "$(grep FOUND$ $CLAMSCANTMP)" ] && \ grep FOUND $CLAMSCANTMP | mail -s "Virus Found in `hostname`" root rm -f $CLAMSCANTMP [root@sample ~]# chmod 700 scan.sh ← 赋予脚本可被执行的权限 [root@sample ~]# crontab -e ← 编辑计划任务，添加如下行 00 03 * * * /root/scan.sh ← 添加这一行，让其在每天3点钟执行扫描(责任编辑：IT) |