我想知道我的服务器是否存在安全漏洞。我正在预览 /var/log/messages 文件，我收到了很多登录和退出的消息，然后还有一些关于“网络无法访问解析”的消息。以下是消息文件中最后几条条目的示例。我运行的是 Centos 5.1。
Sep 24 10:03:23 ip-184-168-116-73 pure-ftpd: ([email protected]) [INFO] New connection from 127.0.0.1
Sep 24 10:03:23 ip-184-168-116-73 pure-ftpd: ([email protected]) [INFO] __cpanel__service__auth__ftpd__mYPM6aAnC9051nEC0nS9vPMkaMz34VyA0HXbDApw_0Xan5OW3K9uqnlSAk98PzAq is now logged in
Sep 24 10:03:23 ip-184-168-116-73 pure-ftpd: (__cpanel__service__auth__ftpd__mYPM6aAnC9051nEC0nS9vPMkaMz34VyA0HXbDApw_0Xan5OW3K9uqnlSAk98PzAq@127.0.0.1) [INFO] Logout.
Sep 24 10:08:23 ip-184-168-116-73 pure-ftpd: ([email protected]) [INFO] New connection from 127.0.0.1
Sep 24 10:08:24 ip-184-168-116-73 pure-ftpd: ([email protected]) [INFO] __cpanel__service__auth__ftpd__qUTJ2NFXeRRKXGjXVbjLQn2upJdGRaSGGSMDQna8wsEINYCTOrWUzxqiJp8rUT0S is now logged in
Sep 24 10:08:24 ip-184-168-116-73 pure-ftpd: (__cpanel__service__auth__ftpd__qUTJ2NFXeRRKXGjXVbjLQn2upJdGRaSGGSMDQna8wsEINYCTOrWUzxqiJp8rUT0S@127.0.0.1) [INFO] Logout.
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: network unreachable resolving 'ns1.expired.r01.ru/A/IN': 2001:678:17:0:193:232:128:6#53
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: network unreachable resolving 'ns2.expired.r01.ru/A/IN': 2001:678:17:0:193:232:128:6#53
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: network unreachable resolving 'ns1.expired.r01.ru/AAAA/IN': 2001:678:17:0:193:232:128:6#53
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: network unreachable resolving 'ns2.expired.r01.ru/AAAA/IN': 2001:678:17:0:193:232:128:6#53
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: unexpected RCODE (SERVFAIL) resolving 'ns1.internet-spb.ru/A/IN': 109.70.26.37#53
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: unexpected RCODE (SERVFAIL) resolving 'ns2.internet-spb.ru/A/IN': 109.70.26.37#53
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: unexpected RCODE (SERVFAIL) resolving 'ns2.internet-spb.ru/AAAA/IN': 109.70.26.37#53
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: unexpected RCODE (SERVFAIL) resolving 'ns1.internet-spb.ru/AAAA/IN': 109.70.26.37#53
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: unexpected RCODE (SERVFAIL) resolving 'ns2.internet-spb.ru/A/IN': 194.85.61.76#53
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: unexpected RCODE (SERVFAIL) resolving 'ns2.internet-spb.ru/AAAA/IN': 194.85.61.76#53
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: unexpected RCODE (SERVFAIL) resolving 'ns1.internet-spb.ru/A/IN': 194.85.61.76#53
Sep 24 10:09:19 ip-184-168-116-73 named[1502]: unexpected RCODE (SERVFAIL) resolving 'ns1.internet-spb.ru/AAAA/IN': 194.85.61.76#53
Sep 24 10:12:11 ip-184-168-116-73 named[1502]: network unreachable resolving 'ns3.rnc.ro/A/IN': 2001:500:2e::1#53
Sep 24 10:13:25 ip-184-168-116-73 pure-ftpd: ([email protected]) [INFO] New connection from 127.0.0.1
Sep 24 10:13:25 ip-184-168-116-73 pure-ftpd: ([email protected]) [INFO] __cpanel__service__auth__ftpd__s4ls4qxg3HrWFYi6ICTo0SJvgbJU6DSbALi95PAgNGK2rHENueFdmzXwkXY7GjMj is now logged in
Sep 24 10:13:25 ip-184-168-116-73 pure-ftpd: (__cpanel__service__auth__ftpd__s4ls4qxg3HrWFYi6ICTo0SJvgbJU6DSbALi95PAgNGK2rHENueFdmzXwkXY7GjMj@127.0.0.1) [INFO] Logout.
Sep 24 10:16:15 ip-184-168-116-73 named[1502]: client 199.180.114.183#36635: query (cache) 'cpsc.gov/ANY/IN' denied
如果这是黑客攻击，那么我需要更改哪些设置以确保更高的安全性？
谢谢你，上帝保佑<><
答案1
看起来 (a) 您的 IPv6 配置可能出现问题，并且 (b) 有东西进入了您的邮箱（通常是垃圾邮件），导致 DNS 查找垃圾邮件/不存在的域，从而导致失败。
信息量真的不够，无法判断你是否受到了攻击。不过请记住，EL5 现在只获得维护更新……所以此时你可能需要考虑 EL7
此外，Centos 5 目前是 5.11 版本，所以如果你实际上是按照上面建议的那样使用 5.1 版本，那么你可能希望尽快解决这个问题