看看我的CentOS 5.2是不是受到攻击了？

alex_99

2. --------------------- Automount Begin ------------------------
4. **Unmatched Entries**
5. create_tcp_client:299: hostname lookup failed: No such file or directory: 2 Time(s)
6. create_udp_client:90: hostname lookup failed: Operation not permitted: 276 Time(s)
7. lookup_mount: exports lookup failed for sf: 276 Time(s)
8. create_tcp_client:299: hostname lookup failed: Operation not permitted: 274 Time(s)
10. ---------------------- Automount End -------------------------

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开启的服务有：openssh,tomcat 有时也开启proftp
如果是攻击，要怎么阻止？谢谢