July | 2020 | ASGAUR

To use curl to test basic network connectivity, you need to know several things:

The remote server name or IP address.
The protocol for the service to be tested (HTTP, FTP, SMTP, etc.)
The port number for the network application you want to test.

To open a connection to a remote server, open a terminal window on your computer, and then type curl protocol://IP/host:port, where protocol is the communication protocol to be used IP/host represents the IP address or hostname of the server, and port represents the TCP port number. Port is optional when the standard port for a given protocol is used.

C:\>curl http://asgaur.com
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>301 Moved Permanently</title>
</head><body>
<h1>Moved Permanently</h1>
<p>The document has moved <a href="http://asgaur.com/wp/">here</a>.</p>
</body></html>

Use curl to try and connect via SMTP protocol

C:\>curl smtp://asgaur.com
C:\>curl smtp://asgaur.com:2525 (2525 custom port if any)
214-Commands supported:
214 AUTH STARTTLS HELO EHLO MAIL RCPT DATA BDAT NOOP QUIT RSET HELP

To test an FTP server, use curl to connect via ftp protocol or to port 21.

C:\>curl ftp://asgaur.com
C:\>curl asgaur.com:21
220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
220-You are user number 18 of 50 allowed.
220-Local time is now 10:04. Server port: 21.
220-This is a private system - No anonymous login
220-IPv6 connections are also welcome on this server.
220 You will be disconnected after 15 minutes of inactivity.

SSH uses encrypted connections. However, you can still use curl to verify that the service is running on a server.

C:\>curl asgaur.com:22
SSH-2.0-OpenSSH_XX

Problem described as below-

Getting passwd: Authentication token manipulation error on RHEL6 Machine.

[root@ip-linuxbox~]# passwd user1
Changing password for user user1.
New password:
Retype new password:
passwd: Authentication token manipulation error

[root@ip-linuxbox~]# passwd -u user1 [Tried to unlock the account password.]
Unlocking password for user user1.
passwd: Libuser error at line: 179 – error creating `/etc/passwd+’: Permission denied.
passwd: Error (password not set?) [Getting Permission denied error hence passwd is not getting changed/updated. Hence, we need to restore the permission on passwd.]

[root@ip-linuxbox~]# chage -l user1
Last password change : Apr 03, 2019
Password expires : never
Password inactive : never
Account expires : never
Minimum number of days between password change : 0
Maximum number of days between password change : 99999
Number of days of warning before password expires : 7

Solution-

[root@ip-linuxbox~]# rpm –setperms passwd [Restore permission on passwd file.]

[root@ip-linuxbox~]# which passwd | xargs chmod u+s [Setting required permission on passwd file.]

[root@ip-linuxbox ~]# restorecon /etc/* [ if SELinux context is properly set for, it will fix the same.]

[root@ip-linuxbox~]# passwd user1
Changing password for user user1.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.

[root@ip-linuxbox~]# chage -l user1
Last password change : Jul 28, 2020
Password expires : never
Password inactive : never
Account expires : never
Minimum number of days between password change : 0
Maximum number of days between password change : 99999
Number of days of warning before password expires : 7

ASGAUR

Monthly Archives: July 2020

USING CURL TO TROUBLESHOOT

passwd: Authentication token manipulation error | RHEL 6