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One that got away – 12.3 Networking

March 13th, 2013 by

Well openSUSE 12.3 is about to go live  and we are all pretty excited. It is, as far as I can tell a rock solid release and we have outdone ourselves. Considering the short release cycle makes this even more impressive.

One can only thank everyone in the community for pulling together, getting a lot of stuff done and delivering a great release.

Yet, there’s one sprinkle that rains on our parade. While we completed the switch to systemd we somewhere along the lines forgot to check the status of NetworkManager on an installed system. Thus, when you upgrade from a previous release and NetworkManager is disabled, it will be enabled and running after the upgrade is complete, sorry. If you happen to be running a network bridge your bridge will not be working and you’ll end up in some weird network state where ifconfig will tell you that both your bridge and your Ethernet card have an IP address. Your routing table will also be messed up. Addressing the issue is easy.

Login as root, which you will have to do at the login manager if you happen to run NIS, disable NetworkManager, stop the NetworkManager service, and restart your network. You are now back to your original configuration, no sweat ūüėČ . Below is a list of commands you want to run as the root user to make this happen:

# systemctl –force disable NetworkManager.service

# systemctl stop NetworkManager.service

# rcnetwork restart

Securing SSH (Secure Shell) from attacker

March 22nd, 2011 by

Secure Shell or SSH is a network protocol that allows exchange of data through secure channels between two network devices.

Particularly widely used on Linux and Unix-based system to access your shell, SSHwas designed as a substitute for Telnet and other insecure remote shells, which sentinformation, especially passwords, in the form of simple text that makes it easy to be intercepted. Encryption used by SSH provides confidentiality and integrity of dataover an insecure network like the Internet.

For the Security Server We From Attacks The attacker who usually Always Use SSHAs a door Early Entry Into System To us, of course, become an admin obligation todispel various Efforts That.

There are several ways which ordinary people do to secure SSH from a variety ofattacks which one of them is by editing the file / etc / ssh / sshd_config.

before doing the configuration in the file / etc / ssh / sshd_config make sure SSH isinstalled on your linux distribution, and for openSUSE that I use it already automatically installed.

#vim /etc/ssh/sshd_config

change options, as below :

LoginGraceTime 2m
PermitRootLogin no
MaxAuthTries 3

LoginGraceTime which option is used to give a time limit of user logins, so please change these options according to your wishes.

PermitRootLogin is no option to allow the root user can login to ssh or not to give yes or no value on the options tersebut.sebaiknya give no value, so that users can not loginas root into your ssh.

MaxAuthTries 3 to give the limit on the number of errors allowed when the user logs in,this is very useful to avoid attackers do brute force on the server anda.dimana usersonly allowed to make a mistake typing the password in accordance with that alreadyset on the options.

If you want only certain users who may log into your ssh add AllowUsers option at the end of the line followed by a distinguished user name in the allowed login.

otherwise, you can install software, denyhost, for your ssh security

NB:do not enable the root user, for ssh login

Similarly, a fairly simple tutorial .. hopefully this can be useful.

Best Regards
Saydul Akram
Email : idulk@opensuse.org