Linux System Security (2)

When studying Linux, you may encounter Linux system problems. Here we will introduce the solution to Linux system problems. Here we will share with you some ideas.

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Network security, security information, websites
Http://www.cert.org.tw
Http://www.vtcif.telstra.com.au/info/security.html
Http://www.redhat.com/apps/support/errata/
Wu-ftp, zlib, UW imap, openssh, and ssnldap
.....
Http://www.securityfocus.com/
Http://safe.ip-market.com/
Discussion Group/newsgroup
News: comp. security. announce
Mail List/Technical Forum
Listserv@securityfocus.com
Digest@sams.org
Magazines, service program vulnerabilities and patches, service program quantity P12-3, centralized vs distributed
Updated wu-ftp, bind, sendmail, test, chroot skills, use time, and software
Http://www.study-area.org/tips/dns_chr.htm
Difficulties
Application of tcpwrapper, Compile time vs run time, Supper daemon vs tcp_wrapper P15-2, Inetd vs xinetd P11-2, hosts. allow vs hosts. deny P15-9
Services * Appendix 1, firewall and NAT, firewall type, proxy vs filtering P16-1/P17-1, firewall working principle
Http://www.study-area.org/network/network_fw.htm
Basic knowledge
Http://www.study-area.org/linux/servers/linux_nat.htm
Firewall rule design, ACL vs state list, NAT application scenarios, NAT types, SNAT vs DNAT, Statice vs Dynamic
Http://www.study-area.org/tips/NAT-HOWTO/NAT-HOWTO-chn-3.html
Design and deployment of network architecture, trusted network vs untrusted network, DMZ application, physical segmentation, Protocol Switching, common attack methods, DoS, Ping of death P13-2, Syn Flood P13-6, other P13-8, In response to P13-9, self-attack testing, netstat
Http://www.study-area.org/linux/servers/linux_net.htm#network
P25-8 nmap
Portsentry/snort
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Information Encryption, plaintext vs. ciphertext, screen display vs packet content
Http://www.study-area.org/network/network_enscp.htm
What are the prerequisites for listening skills and prevention? , Eavesdropping tools, tcpdump, sniffit, interception point routing? , Hub vs Swtich CSMA/CD? , Encryption methods and principles, encryption principles, original encryption methods
Http://www.study-area.org/network/network_enscp.htm
Algorithms, technology patents, encryption technologies, symmetric keys vs asymmetric keys
Http://www.study-area.org/network/network_enscp.htm
United States export restrictions, electronic signatures, paper vs electronics, verifiable/non-repudiation, current and future of electronic transactions, secure connections, ssl & ssh, and cracking costs
Http://www.study-area.org/tips/security.htm
Http://www.nchu.edu.tw/trnc/90-2/firewall.ppt)
How ssh works
Http://www.study-area.org/tips/security.htm
Vpn construction, VPN principles, and application scenarios
VPN solution: ssh, vpnd,
Http://www.study-area.org/tips/vpn.htm
Ipsec P21-3
Network Design vs Implementation Technology subnet/routing?

Implementation reference
Secure Server Environment (1)
Http://safe.ip-market.com/article.php? Sid = 5
Ten Tips to ensure Linux security
Http://safe.ip-market.com/article.php? Sid = 26
Linux Security Settings Manual (post)
Http://phorum.study-area.org/viewtopic.php? T = 5080 & highlight = time-out % 3D00

Example 1: GRUB Password protection

(1) Enter grub to generate the MD5 password:
Grub> md5crypt
Password :**********
Encrypted: $1 $ U $ JK7xFegdxWH6VuppCUSIb.
** Click the left button to select the password and enter quit to exit grub.

(2) Modify/etc/grub. conf to set password protection:
Password -- md5 $1 $ U $ JK7xFegdxWH6VuppCUSIb.
** Use the mouse key to paste the password.
Title Red Hat Linux 7.3 (2.4.18-3)
Lock
Root (hd0, 1)
Kernel/vmlinuz-2.4.18-3 ro root =/dev/hda12
Initrd/initrd-2.4.18-3.img

3) enter the p and password at startup.
* Example 2: PAM listfile (ssh)
(1) refer to ftp settings:
Grep listfile/etc/pam. d/ftp
(2) simulate it and set it in ssh:
Vi/etc/pam. d/sshd
Add:
Auth required/lib/security/pam_listfile.so item = user \
Sense = deny file =/etc/sshusers onerr = succeed

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Appendix 1: System Service suggestions
Finger strongly recommends that you disable ftp if you do not need it. In particular, anonymous should be disabled. Disable gopher, and disable imap if not needed. Disable pop2 and pop3 if not required. Disable talk, ntalk, or telnet if not required. Replace it with ssh. Uucp is disabled, samba is only open internally, nfs/nis is only open internally, and r-command is closed whenever possible □replace with ssh. , X-protoco

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