Linux, FreeBSD, Juniper, Cisco / Network security articles and troubleshooting guides

**Posted:** Mon Sep 11, 2017 8:52 am

MAC OS X provides a tool to analyze image/jpeg EXIF metadata, including GPS coordinates of the photo, the camera it was taken on and so on.

Quote:

MDLS(1) BSD General Commands Manual MDLS(1)

NAME
mdls -- lists the metadata attributes for the specified file

SYNOPSIS
mdls [-raw ] file ...

DESCRIPTION
The mdls command prints the values of all the metadata attributes associated with the files provided as an argument.

The following options ...

**Posted:** Tue May 05, 2015 5:06 pm

The following Cisco SSH error will be encountered after password is entered:

Code:

Received disconnect from 5.105.4.98: 2: Protocol error: expected packet type 61, got -1

To solve this, check the ssh login timeout which may be too aggressive for strong passwords:

Code:

#sh run | i ssh time
ip ssh time-out 5

In this case, if the password is not entered in 5 seconds, Cisco IOS ssh will disconnect the client.

**Posted:** Tue Mar 10, 2015 5:46 pm

Code:

root@ubuntu-vpsie:~# blkid
/dev/sr0: LABEL="Ubuntu 14.04.2 LTS amd64" TYPE="iso9660"
/dev/sda1: UUID="72a18500-a7fe-41cc-b7b6-72367439424a" TYPE="ext4"
/dev/sda5: UUID="8be2383f-aeb9-408a-933e-0cf62696f0d9" TYPE="swap"
root@ubuntu-vpsie:~# lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0     8G  0 disk
├─sda1   8:1    0     7G  0 part /
├─sda2   8:2    0     1K  0 part
└─sda5   8:5    0  1022M  0 part [SWAP]
sr0     11:0    1   996M  0 rom  /media/andrei--ubuntu/Ubuntu 14.04.2 LTS amd64

**Posted:** Tue Mar 10, 2015 5:45 pm

Quote:

ESCRIPTION
When, as is customary, the proc filesystem is mounted on /proc, you can find in the file /proc/filesystems which filesystems your kernel
currently supports. If you need a currently unsupported one, insert the corresponding module or recompile the kernel.

root@ubuntu-vpsie:~# cat /proc/filesystems
nodev sysfs
nodev rootfs
nodev ramfs
nodev bdev
nodev proc
nodev cgroup
nodev cpuset
nodev tmpfs
nodev devtmpfs
nodev debugfs
nodev securityfs
nodev sockfs
nodev pipefs
nodev devpts
ext3
ext2
ext4
nodev ...

**Posted:** Tue Mar 03, 2015 8:24 am

Rsync is a powerful tool to transfer files from one server to another or from one directory to another. To enable progress display while you transfer a file use the --progress switch (double dash).

Quote:

--progress show progress during transfer

Example how to use rsync progress display

Code:

$ rsync --progress source:/tmp/file .
file
      2,359,296   0%    1.07MB/s    0:14:39  

---------
Syncronizing directories from a remote directory to local directory or vice-versa can be done using rsync. ...

**Posted:** Tue Mar 03, 2015 8:20 am

Linux clear screen terminal and move the shell prompt to the top of the screen.

Linux terminal can get filled with a lot of text if you use cat instead of less or more or if you are grepping a file for a pattern that is very loose.

Also, if you login via a serial console and the shell prompt gets moved in the middle of the screen overlapping with previous boot screen messages.

Clear ...

**Posted:** Mon Feb 09, 2015 4:55 pm

Following error occurs when executing nginx in FreeBSD:

Code:

Shared object "libpcre.so.1" not found, required by "nginx"

This requires "pcre" package to be installed:

Code:

$ pkg install pcre

**Posted:** Mon Feb 09, 2015 4:53 pm

Linux kernel virtual memory model is paged. This means the virtual memory space is divided into small units called “pages”, to quote wikipedia: “blocks of contiguous virtual memory addresses”.

To query configuration of the Linux virtual memory, use “getconf” utility:

Code:

$ getconf -a | grep PAGE
PAGESIZE                           4096
PAGE_SIZE                          4096

The amount is expressed in bytes.

**Posted:** Thu Jan 22, 2015 5:14 pm

One of the first things to do when cleaning up a filesystem is finding old, large and no longer necessary files.

Usually on Linux and Mac laptops, directories such as “Downloads” tend to become very large in time. Old installers and archives are the first ones at eating filesystem space.

How to list all files in current directory and sort them by their size.

For files it is enough to use the “ls” command. Either ...

**Posted:** Tue Jan 20, 2015 4:15 am

GPG key retrieval failed: OSError: No such file or directory: '/etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL'

This fix requires fetching the GPG key from fedora website:

Code:

# cd /etc/pki/rpm-gpg
# wget --no-check-certificate https://dl.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL

Linux, FreeBSD, Juniper, Cisco / Network security articles and troubleshooting guides

News of System administration

Site map of System administration » Forum : System administration

Example how to use rsync progress display

How to list all files in current directory and sort them by their size.

Last 10 active topics

Tutorials for general Unix

Juniper SRX

Shell Scripting and Programming

Virtualization

OpenLDAP - Lightweight Directory Access Protocol

Routing and dynamic routing protocols

TCP/IP Networking

Login

Statistics