I would like to give some examples to describe practical meaning of hard links,soft links and cache in memory in a linux system. I will start creating two ramdisk partitions: # mkdir /ramdisk1 [root@tux ~]# mkdir /ramdisk2 [root@tux ~]# mount none -t tmpfs -o size=256m /ramdisk1 [root@tux ~]# mount none -t tmpfs -o size=256m /ramdisk2
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You can use ulimit command to prevent users from abusing system resources. Below I will touch two of the options; root@deb1:~# ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 15957 max locked memory (kbytes, -l) 64 max
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Imagine that you have a host (named A) somewhere that has no publicly reachable IP address but you would like to connect it via SSH. If this host A can reach outside, then you can reverse SSH into it. Here is the scenario; Host A (192.168.1.1) — INTERNET —- Host C (10.10.10.1) On host A,
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If you want to analyse for example apache log files and split the lines by space by using the usual “split” method, you will see that split doesn’t respect quoted strings. For example if you have a line like below; 192.168.2.1 – – [06/Mar/2012:10:02:22 +0100] “GET /2011/10/19/jncip-sec-exam/ HTTP/1.1” 200 3331 “-” “mm” You can’t get
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I am sure from time to time you need to run an operational command on multiple junos devices e.g deleting a specific file from all devices. It is up to you of course what sort of commands you can run. For the following script to work you should also install python paramiko module. You may
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I used to remember that junos by default keeps 50 configuration rollbacks by number through 0 to 49. However in a default setup when I saw that I only have up to number 5 rollback, I realized that default isn’t 50 config files. Once you set the command; #set system max-configuration-rollbacks 49 you can keep
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To test how SRX blocks skype logins I have done the followings test and it worked; 1) Create a test IDP policy named My_Policy root@ankara# show idp-policy My_Policy rulebase-ips { rule 1 { match { source-address any; destination-address any; application default; attacks { predefined-attacks [ VOIP:SKYPE:LOGIN VOIP:SKYPE:PROBE-1 ]; } } then { action { close-client;
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I would like to share my experiment on uninstalling of IDP module on an SRX100 device. Please take this as a test case and use it at your own discretion as I just test a manual removal of files and re-installed IDP module. 1) First disable IDP process root@ankara# set system processes idp-policy disable 2)
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If you want to find how many times a single word is repeated in a file, I have quoted my code below. The method that I didn’t know before was the “get” method. It allows you to get the value of the key but if it isn’t set before, set the value specified in our
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There are several ways of blocking certain type of traffic. One of them is a firewall filter. You may be asking why to use firewall filter instead of a security policy. The reason is firewall filter is at the very early stage of packet processing and it needs less processing power than security policies. You
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