What is logging in?
From https://unix.stackexchange.com/a/489913/674
Logging in is a user-space construct; the kernel doesn’t care about that.
There are multiple examples of this; for example, cron jobs can run as any user, without that user being logged in. ... connecting using SSH counts as logging in.
Since there are examples which have and which don't have logging in, may I ask what logging in is? What activities counts as logging in and what not?
Let me guess. Is any activity involving asking for user name and its password, and checking that information in /etc/passwd and /etc/shadow counted as logging in? Otherwise, not logging in?
Is running su logging in?
Is running sudo logging in? Or not, because it doesn't ask for the target user's password?
What are some other educational examples?
Thanks.
ssh sudo cron login su
asked Dec 20 '18 at 13:06
Tim
26.1k74246455
add a comment |
From https://unix.stackexchange.com/a/489913/674
Logging in is a user-space construct; the kernel doesn’t care about that.
There are multiple examples of this; for example, cron jobs can run as any user, without that user being logged in. ... connecting using SSH counts as logging in.
Since there are examples which have and which don't have logging in, may I ask what logging in is? What activities counts as logging in and what not?
Let me guess. Is any activity involving asking for user name and its password, and checking that information in /etc/passwd and /etc/shadow counted as logging in? Otherwise, not logging in?
Is running su logging in?
Is running sudo logging in? Or not, because it doesn't ask for the target user's password?
What are some other educational examples?
Thanks.
ssh sudo cron login su
asked Dec 20 '18 at 13:06
Tim
26.1k74246455
From Wikipedia: 'In computer security, logging in (or logging on or signing in or signing on) is the process by which an individual gains access to a computer system by identifying and authenticating themselves. '
– Haxiel
Dec 20 '18 at 13:12
As my understanding, logging in means that the kernel will handle a process, which creates a TTY. The TTY allows user to communicate with the OS through some kind of shell, such as bash, csh, zsh etc.
– Yves
Dec 20 '18 at 13:13
@arochester comments should only be used to ask for clarification. Please don't leave useless comments.
– terdon♦
Dec 20 '18 at 15:12
add a comment |
From https://unix.stackexchange.com/a/489913/674
Logging in is a user-space construct; the kernel doesn’t care about that.
There are multiple examples of this; for example, cron jobs can run as any user, without that user being logged in. ... connecting using SSH counts as logging in.
Since there are examples which have and which don't have logging in, may I ask what logging in is? What activities counts as logging in and what not?
Let me guess. Is any activity involving asking for user name and its password, and checking that information in /etc/passwd and /etc/shadow counted as logging in? Otherwise, not logging in?
Is running su logging in?
Is running sudo logging in? Or not, because it doesn't ask for the target user's password?
What are some other educational examples?
Thanks.
ssh sudo cron login su
asked Dec 20 '18 at 13:06
Tim
26.1k74246455
From https://unix.stackexchange.com/a/489913/674
Logging in is a user-space construct; the kernel doesn’t care about that.
There are multiple examples of this; for example, cron jobs can run as any user, without that user being logged in. ... connecting using SSH counts as logging in.
Since there are examples which have and which don't have logging in, may I ask what logging in is? What activities counts as logging in and what not?
Let me guess. Is any activity involving asking for user name and its password, and checking that information in /etc/passwd and /etc/shadow counted as logging in? Otherwise, not logging in?
Is running su logging in?
Is running sudo logging in? Or not, because it doesn't ask for the target user's password?
What are some other educational examples?
Thanks.
ssh sudo cron login su
ssh sudo cron login su
asked Dec 20 '18 at 13:06
Tim
26.1k74246455
asked Dec 20 '18 at 13:06
Tim
26.1k74246455
edited Dec 20 '18 at 13:18
asked Dec 20 '18 at 13:06
Tim
26.1k74246455
asked Dec 20 '18 at 13:06
Tim
26.1k74246455
asked Dec 20 '18 at 13:06
Tim
26.1k74246455
26.1k74246455
From Wikipedia: 'In computer security, logging in (or logging on or signing in or signing on) is the process by which an individual gains access to a computer system by identifying and authenticating themselves. '
– Haxiel
Dec 20 '18 at 13:12
As my understanding, logging in means that the kernel will handle a process, which creates a TTY. The TTY allows user to communicate with the OS through some kind of shell, such as bash, csh, zsh etc.
– Yves
Dec 20 '18 at 13:13
@arochester comments should only be used to ask for clarification. Please don't leave useless comments.
– terdon♦
Dec 20 '18 at 15:12
add a comment |
From Wikipedia: 'In computer security, logging in (or logging on or signing in or signing on) is the process by which an individual gains access to a computer system by identifying and authenticating themselves. '
– Haxiel
Dec 20 '18 at 13:12
As my understanding, logging in means that the kernel will handle a process, which creates a TTY. The TTY allows user to communicate with the OS through some kind of shell, such as bash, csh, zsh etc.
– Yves
Dec 20 '18 at 13:13
@arochester comments should only be used to ask for clarification. Please don't leave useless comments.
– terdon♦
Dec 20 '18 at 15:12
From Wikipedia: 'In computer security, logging in (or logging on or signing in or signing on) is the process by which an individual gains access to a computer system by identifying and authenticating themselves. '
– Haxiel
Dec 20 '18 at 13:12
From Wikipedia: 'In computer security, logging in (or logging on or signing in or signing on) is the process by which an individual gains access to a computer system by identifying and authenticating themselves. '
– Haxiel
Dec 20 '18 at 13:12
As my understanding, logging in means that the kernel will handle a process, which creates a TTY. The TTY allows user to communicate with the OS through some kind of shell, such as bash, csh, zsh etc.
– Yves
Dec 20 '18 at 13:13
As my understanding, logging in means that the kernel will handle a process, which creates a TTY. The TTY allows user to communicate with the OS through some kind of shell, such as bash, csh, zsh etc.
– Yves
Dec 20 '18 at 13:13
@arochester comments should only be used to ask for clarification. Please don't leave useless comments.
– terdon♦
Dec 20 '18 at 15:12
@arochester comments should only be used to ask for clarification. Please don't leave useless comments.
– terdon♦
Dec 20 '18 at 15:12
add a comment |
1 Answer
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At the most basic level, it can be considered "authenticating to a service to obtain resources from that service".
But, in Unix, the term isn't so strictly defined. Different services can interpret in different ways.
Where terminology gets confused is when you think of "logging into Unix" and getting a "login session", rather than "accessing a service".
So, for example, ssh remotemachine is considered logging in, but ssh remotemachine cat /etc/passwd may not be (sshd will perform different actions, log different data, update different files); they're both authenticating to a service and getting resources... but the second version is not considered a "login session".
Also note that authentication need not be using the passwd and shadow files (e.g. an FTP server could use a different authentication database, or SSH public keys may be used, or a kerberos ticket, or...).
answered Dec 20 '18 at 14:27
Stephen Harris
25.1k24477
Is it safe to say that "logging in" == "starting a login shell"? Or can you log in without starting a shell?
– terdon♦
Dec 20 '18 at 15:13
@terdon FTP, IMAP and other services may have a login process, but don't provide a shell. Conversely, ssh host /bin/sh -i will provide a prompt, but not a login session.
– Stephen Harris
Dec 20 '18 at 22:14
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
At the most basic level, it can be considered "authenticating to a service to obtain resources from that service".
But, in Unix, the term isn't so strictly defined. Different services can interpret in different ways.
Where terminology gets confused is when you think of "logging into Unix" and getting a "login session", rather than "accessing a service".
So, for example, ssh remotemachine is considered logging in, but ssh remotemachine cat /etc/passwd may not be (sshd will perform different actions, log different data, update different files); they're both authenticating to a service and getting resources... but the second version is not considered a "login session".
Also note that authentication need not be using the passwd and shadow files (e.g. an FTP server could use a different authentication database, or SSH public keys may be used, or a kerberos ticket, or...).
answered Dec 20 '18 at 14:27
Stephen Harris
25.1k24477
Is it safe to say that "logging in" == "starting a login shell"? Or can you log in without starting a shell?
– terdon♦
Dec 20 '18 at 15:13
@terdon FTP, IMAP and other services may have a login process, but don't provide a shell. Conversely, ssh host /bin/sh -i will provide a prompt, but not a login session.
– Stephen Harris
Dec 20 '18 at 22:14
add a comment |
At the most basic level, it can be considered "authenticating to a service to obtain resources from that service".
But, in Unix, the term isn't so strictly defined. Different services can interpret in different ways.
Where terminology gets confused is when you think of "logging into Unix" and getting a "login session", rather than "accessing a service".
So, for example, ssh remotemachine is considered logging in, but ssh remotemachine cat /etc/passwd may not be (sshd will perform different actions, log different data, update different files); they're both authenticating to a service and getting resources... but the second version is not considered a "login session".
Also note that authentication need not be using the passwd and shadow files (e.g. an FTP server could use a different authentication database, or SSH public keys may be used, or a kerberos ticket, or...).
answered Dec 20 '18 at 14:27
Stephen Harris
25.1k24477
Is it safe to say that "logging in" == "starting a login shell"? Or can you log in without starting a shell?
– terdon♦
Dec 20 '18 at 15:13
@terdon FTP, IMAP and other services may have a login process, but don't provide a shell. Conversely, ssh host /bin/sh -i will provide a prompt, but not a login session.
– Stephen Harris
Dec 20 '18 at 22:14
add a comment |
At the most basic level, it can be considered "authenticating to a service to obtain resources from that service".
But, in Unix, the term isn't so strictly defined. Different services can interpret in different ways.
Where terminology gets confused is when you think of "logging into Unix" and getting a "login session", rather than "accessing a service".
So, for example, ssh remotemachine is considered logging in, but ssh remotemachine cat /etc/passwd may not be (sshd will perform different actions, log different data, update different files); they're both authenticating to a service and getting resources... but the second version is not considered a "login session".
Also note that authentication need not be using the passwd and shadow files (e.g. an FTP server could use a different authentication database, or SSH public keys may be used, or a kerberos ticket, or...).
answered Dec 20 '18 at 14:27
Stephen Harris
25.1k24477
At the most basic level, it can be considered "authenticating to a service to obtain resources from that service".
But, in Unix, the term isn't so strictly defined. Different services can interpret in different ways.
Where terminology gets confused is when you think of "logging into Unix" and getting a "login session", rather than "accessing a service".
So, for example, ssh remotemachine is considered logging in, but ssh remotemachine cat /etc/passwd may not be (sshd will perform different actions, log different data, update different files); they're both authenticating to a service and getting resources... but the second version is not considered a "login session".
Also note that authentication need not be using the passwd and shadow files (e.g. an FTP server could use a different authentication database, or SSH public keys may be used, or a kerberos ticket, or...).
answered Dec 20 '18 at 14:27
Stephen Harris
25.1k24477
answered Dec 20 '18 at 14:27
Stephen Harris
25.1k24477
answered Dec 20 '18 at 14:27
Stephen Harris
25.1k24477
answered Dec 20 '18 at 14:27
Stephen Harris
25.1k24477
25.1k24477
Is it safe to say that "logging in" == "starting a login shell"? Or can you log in without starting a shell?
– terdon♦
Dec 20 '18 at 15:13
@terdon FTP, IMAP and other services may have a login process, but don't provide a shell. Conversely, ssh host /bin/sh -i will provide a prompt, but not a login session.
– Stephen Harris
Dec 20 '18 at 22:14
add a comment |
Is it safe to say that "logging in" == "starting a login shell"? Or can you log in without starting a shell?
– terdon♦
Dec 20 '18 at 15:13
@terdon FTP, IMAP and other services may have a login process, but don't provide a shell. Conversely, ssh host /bin/sh -i will provide a prompt, but not a login session.
– Stephen Harris
Dec 20 '18 at 22:14
Is it safe to say that "logging in" == "starting a login shell"? Or can you log in without starting a shell?
– terdon♦
Dec 20 '18 at 15:13
Is it safe to say that "logging in" == "starting a login shell"? Or can you log in without starting a shell?
– terdon♦
Dec 20 '18 at 15:13
@terdon FTP, IMAP and other services may have a login process, but don't provide a shell. Conversely, ssh host /bin/sh -i will provide a prompt, but not a login session.
– Stephen Harris
Dec 20 '18 at 22:14
@terdon FTP, IMAP and other services may have a login process, but don't provide a shell. Conversely, ssh host /bin/sh -i will provide a prompt, but not a login session.
– Stephen Harris
Dec 20 '18 at 22:14
add a comment |
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From Wikipedia: 'In computer security, logging in (or logging on or signing in or signing on) is the process by which an individual gains access to a computer system by identifying and authenticating themselves. '
– Haxiel
Dec 20 '18 at 13:12
As my understanding, logging in means that the kernel will handle a process, which creates a TTY. The TTY allows user to communicate with the OS through some kind of shell, such as bash, csh, zsh etc.
– Yves
Dec 20 '18 at 13:13
@arochester comments should only be used to ask for clarification. Please don't leave useless comments.
– terdon♦
Dec 20 '18 at 15:12