What actions are necessary for undertaking, if also you appeared among injured from breaking:

1. To rescue the necessary information (not established programs) from disks on other machine and to rearrange ALL system from the distribution kit. It is possible and with damp but only in the event that you are sure that you damp has been made BEFORE breaking. " All necessary information " are understood as options of everything that works, users / groups, catalogues of users with contents, etc. At rescue of this information it is necessary to pay attention to some user files - ~/.rhosts, ~/bin/* - it is especially close(attentive), and also on possible(probable) traces of work of programs which try to select passwords, strange broad gullies IRC, etc. It is recommended to check up also file system on presence of the left tool means - scripts, source codes of programs. If the program of interception of a network is found out in you ( sniffer) be not too lazy and check up all file system in searches of the report of work of this program. If searches will crown success - closely analyze a find, probably it will affect you will use what reports and means of protection further. Besides the big request - to keep this file and to send its technical experts of your provider (the critical information for you can remove).

2. After reinstallation to change ALL passwords, and to not overlook to change their once a month. It is recommended to not use passwords, 6 symbols or consisting of easily predicted words are shorter.

3. Closely to look on/etc/inetd.conf and to remove there from all services which you do not use, and also remove (whenever possible) all r commands (shell, exec, login). By the machine that is used should work only.

4. Closely(Attentively) to study starting files -/etc/rc. *,/usr/local/etc/rc.d/* for start of strange programs (start known under the name, but from a strange place here enters, for example from/var/log:-)

5. In a file/etc/rc.conf to put tcp_extensions = "NO" in avoidance DoS (Denial of Service). Especially it in a real life all the same is not used.

6. After the system at you is ready, start mtree with md5 and keep mtree files (details are in man mtree). Except for mtree for the control of integrity it is possible to use other utilities, for example tripwire. In the description all recommendations, but упомяну also are given, that it is necessary to compile it statically (in flags of the compiler and the loader it is added-static), the description is created, to be made initialization then the received standard, where is the Control sums, modes of access and owners of files, it is necessary to copy on a diskette where is located also itself binary programs. Checks should be made in the one-user mode, starting a copy of the program from a diskette. To take the program (with the description) it is possible on (ftp.cert.org)

7. The following stage make a backup copy - damp a zero level and clean(remove) the carrier in a reliable place. In a consequence before you do damp - check system tripwire or mtree (but it is necessary from a diskette).

8. Subscribe for lists of dispatch, for example on freebsd security. Do not hesitate to write there, ask questions, it is especial at detection of strangeness.

With a view of preventive maintenance, try to check on a regular basis files from the list resulted below are the most probable candidates for holes :

/usr/lib/lib*.so.*

/sbin/*

/usr / {bin, sbin, libexec}/*

Well and everything else of type

/etc/*passw*

/etc/logi*

/etc/rc*

/etc/group.

For example, if you established system one month ago, a command

ls-l/usr/sbin/login

Shows time of updating one month ago,

And a command

ls-lc/usr/sbin/login

- Yesterday you almost have for certain suffered

On entrance routers it is very quite good to put filters (with caution - whether at you then all will work). The listed ports - reports or with an insufficient level authoraztion which to manage, or those reports for which is breakable . It is necessary to take into account, that it is the list not full that was recollected is simple. But I think, that initially will suffice with interest, and then you can fill up this list, read corresponding sources:-).

1. udp port 111,69,161,162,514,517,518,2048

2. tcp port 143,110,111,11,12,512,513,514

At installation anonymous FTP it is necessary to observe carefully , it is the best way to put one of specially corrected anonymous servers, such as anonftpd, aftpd. It is meaningful to start them at once with chroot from tcpwrapper, it once again will save you from possible mistakes.