How to check opened/closed ports on my computer?
How to check the opened/closed ports on my computer?
I used netstat -a on command line.
- Does the port status "LISTENING" indicate that the port is open?
- Is any port, that is not shown in the output, closed?
netstat
edited Oct 11 '18 at 16:08
abu_bua
3,27981126
asked Oct 17 '14 at 12:43
RouterRouter
856396
add a comment |
How to check the opened/closed ports on my computer?
I used netstat -a on command line.
- Does the port status "LISTENING" indicate that the port is open?
- Is any port, that is not shown in the output, closed?
netstat
edited Oct 11 '18 at 16:08
abu_bua
3,27981126
asked Oct 17 '14 at 12:43
RouterRouter
856396
Check this post on AskUbuntu!.
– Justgivemeaname
Oct 17 '14 at 12:46
2
@Justgivemeaname:nmapis a tool to check for open ports on another host. If you can runnetstaton a machine, it's much faster and reliable to use it.
– David Foerster
Oct 17 '14 at 14:20
@DavidFoerster: Didn't know aboutnetstat, so I learned that. It says in the link that it should be used from another host, though. Thanks!
– Justgivemeaname
Oct 17 '14 at 14:38
3
Possible duplicate of How can I see what ports are open on my machine?
– Dan Dascalescu
Jan 17 '17 at 20:32
add a comment |
How to check the opened/closed ports on my computer?
I used netstat -a on command line.
- Does the port status "LISTENING" indicate that the port is open?
- Is any port, that is not shown in the output, closed?
netstat
edited Oct 11 '18 at 16:08
abu_bua
3,27981126
asked Oct 17 '14 at 12:43
RouterRouter
856396
How to check the opened/closed ports on my computer?
I used netstat -a on command line.
- Does the port status "LISTENING" indicate that the port is open?
- Is any port, that is not shown in the output, closed?
netstat
netstat
edited Oct 11 '18 at 16:08
abu_bua
3,27981126
asked Oct 17 '14 at 12:43
RouterRouter
856396
edited Oct 11 '18 at 16:08
abu_bua
3,27981126
asked Oct 17 '14 at 12:43
RouterRouter
856396
edited Oct 11 '18 at 16:08
abu_bua
3,27981126
edited Oct 11 '18 at 16:08
abu_bua
3,27981126
edited Oct 11 '18 at 16:08
abu_bua
3,27981126
3,27981126
asked Oct 17 '14 at 12:43
RouterRouter
856396
asked Oct 17 '14 at 12:43
RouterRouter
856396
asked Oct 17 '14 at 12:43
RouterRouter
856396
856396
Check this post on AskUbuntu!.
– Justgivemeaname
Oct 17 '14 at 12:46
2
@Justgivemeaname:nmapis a tool to check for open ports on another host. If you can runnetstaton a machine, it's much faster and reliable to use it.
– David Foerster
Oct 17 '14 at 14:20
@DavidFoerster: Didn't know aboutnetstat, so I learned that. It says in the link that it should be used from another host, though. Thanks!
– Justgivemeaname
Oct 17 '14 at 14:38
3
Possible duplicate of How can I see what ports are open on my machine?
– Dan Dascalescu
Jan 17 '17 at 20:32
add a comment |
Check this post on AskUbuntu!.
– Justgivemeaname
Oct 17 '14 at 12:46
2
@Justgivemeaname:nmapis a tool to check for open ports on another host. If you can runnetstaton a machine, it's much faster and reliable to use it.
– David Foerster
Oct 17 '14 at 14:20
@DavidFoerster: Didn't know aboutnetstat, so I learned that. It says in the link that it should be used from another host, though. Thanks!
– Justgivemeaname
Oct 17 '14 at 14:38
3
Possible duplicate of How can I see what ports are open on my machine?
– Dan Dascalescu
Jan 17 '17 at 20:32
Check this post on AskUbuntu!.
– Justgivemeaname
Oct 17 '14 at 12:46
Check this post on AskUbuntu!.
– Justgivemeaname
Oct 17 '14 at 12:46
2
2
@Justgivemeaname:
nmap is a tool to check for open ports on another host. If you can run netstat on a machine, it's much faster and reliable to use it.– David Foerster
Oct 17 '14 at 14:20
@Justgivemeaname:
nmap is a tool to check for open ports on another host. If you can run netstat on a machine, it's much faster and reliable to use it.– David Foerster
Oct 17 '14 at 14:20
@DavidFoerster: Didn't know about
netstat, so I learned that. It says in the link that it should be used from another host, though. Thanks!– Justgivemeaname
Oct 17 '14 at 14:38
@DavidFoerster: Didn't know about
netstat, so I learned that. It says in the link that it should be used from another host, though. Thanks!– Justgivemeaname
Oct 17 '14 at 14:38
3
3
Possible duplicate of How can I see what ports are open on my machine?
– Dan Dascalescu
Jan 17 '17 at 20:32
Possible duplicate of How can I see what ports are open on my machine?
– Dan Dascalescu
Jan 17 '17 at 20:32
add a comment |
7 Answers
7
active
oldest
votes
There's a few parameters to netstat that are useful for this :
-lor--listeningshows only the sockets currently listening for incoming connection.
-aor--allshows all sockets currently in use.
-tor--tcpshows the tcp sockets.
-uor--udpshows the udp sockets.
-nor--numericshows the hosts and ports as numbers, instead of resolving in dns and looking in /etc/services.
You use a mix of these to get what you want. To know which port numbers are currently in use, use one of these:
netstat -atn # For tcp
netstat -aun # For udp
netstat -atun # For both
In the output all port mentioned are in use either listening for incoming connection or connected to a peer** all others are closed. TCP and UDP ports are 16 bits wide (they go from 1-65535)
** They can also be connecting/disconnecting from the peer.
edited Feb 13 '15 at 19:12
muru
1
answered Oct 17 '14 at 13:53
kbenoitkbenoit
1,9271813
add a comment |
You can use this command:
netstat -tulnp | grep <port no>
If it shows some process its used. Its closed(not used) if there is no output.
edited Sep 16 '15 at 12:29
Community♦
1
answered Oct 17 '14 at 12:45
kashminderkashminder
1,060815
add a comment |
Another alternative command line easy to use to find out which process is using a port:
lsof -n -i4TCP:$PORT | grep LISTEN
I added the next function in my .bash_profile,
function pslisten {
echo `lsof -n -i4TCP:$1 | grep LISTEN`
}
and now run "pslisten 5060" to see who is grabing my SIP port.
It's work with Apple Mac OS X too.
answered Mar 13 '15 at 7:22
Fernando SantucciFernando Santucci
8201714
add a comment |
Is the port status "LISTENING" indicated that the port is opened?
Yes. It means that some service is listening to that port on your computer for incoming connection i.e. this port is open for establishing new connections.
Any port that are not shown in the output indicated that it's closed?
Yes. Remember netstat -a will show all active (listening) and passive (non-listening) connections i.e. the ports that are acting as both server (some services are listening to these ports for connections from a different machine/process) and established (connections are established on these ports regardless of the fact the host/a service can be a server or client)
All TCP and UDP ports belong to a category called sockets and there are a whole lot of those. To view socket info you can check man ss.
answered Oct 17 '14 at 13:53
heemaylheemayl
66.3k8139212
Thanks. you wrote that-ameans server and established. Does "server" means ports that are being listened at by some services? Does "established" mean ports where there are existing connections regardless of it is a client or server's port? Then what kinds of ports does-anot show?
– Tim
Aug 21 '18 at 19:28
I don't think the-aoption means "all active" sockets; it just means "all". netstat shows all active sockets by default, but leaves out the passive sockets (open, listening). By using the-aoption both active and passive sockets are shown.
– Egon Olieux
Sep 22 '18 at 8:28
@EgonOlieux Thanks. I stand corrected; edited the answer.
– heemayl
Sep 24 '18 at 20:20
@heemayl The second part of your answer is still not correct. A TCP socket in the "listening" state can never be a connection; it is not connected to anything, it is only listening. Listening TCP sockets are also called passive sockets because of this. If a client attempts to connect to a (listening) socket on a server, a new socket will be created on the server to establish a connection with the client. A socket which is part of an established connection is called an active socket.
– Egon Olieux
Sep 25 '18 at 20:37
add a comment |
Another option is ss. It's much easier to use....
The below command will only output a list of current listening sockets.
root@server:~# ss -l
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
u_dgr UNCONN 0 0 * 23353 * 23352
u_dgr UNCONN 0 0 * 568 * 362
u_dgr UNCONN 0 0 * 14836 * 14837
u_dgr UNCONN 0 0 * 20446 * 369
u_dgr UNCONN 0 0 * 22877 * 369
u_dgr UNCONN 0 0 * 504 * 347
u_dgr UNCONN 0 0 * 16298 * 369
u_dgr UNCONN 0 0 * 23343 * 369
u_dgr UNCONN 0 0 * 24125 * 369
u_dgr UNCONN 0 0 * 24617 * 369
u_dgr UNCONN 0 0 * 23352 * 23353
u_dgr UNCONN 0 0 * 23334 * 369
u_dgr UNCONN 0 0 * 17113 * 369
u_dgr UNCONN 0 0 * 16957 * 369
u_dgr UNCONN 0 0 * 14793 * 362
u_dgr UNCONN 0 0 * 23345 * 362
u_dgr UNCONN 0 0 * 24070 * 369
udp UNCONN 0 0 *:sunrpc *:*
udp UNCONN 0 0 *:981 *:*
udp UNCONN 0 0 :::sunrpc :::*
udp UNCONN 0 0 :::981 :::*
tcp LISTEN 0 128 127.0.0.1:85 *:*
tcp LISTEN 0 128 *:ssh *:*
tcp LISTEN 0 128 *:3128 *:*
tcp LISTEN 0 100 127.0.0.1:smtp *:*
tcp LISTEN 0 128 *:8006 *:*
tcp LISTEN 0 128 *:sunrpc *:*
tcp LISTEN 0 128 :::ssh :::*
tcp LISTEN 0 100 ::1:smtp :::*
tcp LISTEN 0 128 :::sunrpc :::*
answered Feb 5 '18 at 3:37
zeezee
1212
I did not know about this, thanks zee
– nick fox
Feb 8 '18 at 10:19
add a comment |
Or this might help by using watch, then play around with what you want to see.
sudo watch -d -n0 "netstat -atnp | grep ESTA"
sudo watch -d -n0 "netstat -tulnp | grep ESTA"
answered Jan 4 '17 at 11:57
Ian CroasdellIan Croasdell
192
1
-a conflicts with -l, -a grabs all whether ESTABLISHED or LISTENING, and -l just grabs LISTENING, so in reality it is '-ltnp' tcp, '-lunp' udp or '-ltunp' tcp+udp
– ModerateJavaScriptDev
Jul 2 '17 at 23:31
add a comment |
Actually there is a better way to see what ports you have open. The issue with netstat or lsof is that they query network stack and actually do not connect to the machine but instead trying to see what is running on the system. The better approach is to use nmap like so:
nmap -sT -O localhost
To see open ports.
answered Feb 27 '18 at 0:45
DeveloperDeveloper
1133
add a comment |
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7 Answers
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active
oldest
votes
7 Answers
7
active
oldest
votes
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votes
active
oldest
votes
There's a few parameters to netstat that are useful for this :
-lor--listeningshows only the sockets currently listening for incoming connection.
-aor--allshows all sockets currently in use.
-tor--tcpshows the tcp sockets.
-uor--udpshows the udp sockets.
-nor--numericshows the hosts and ports as numbers, instead of resolving in dns and looking in /etc/services.
You use a mix of these to get what you want. To know which port numbers are currently in use, use one of these:
netstat -atn # For tcp
netstat -aun # For udp
netstat -atun # For both
In the output all port mentioned are in use either listening for incoming connection or connected to a peer** all others are closed. TCP and UDP ports are 16 bits wide (they go from 1-65535)
** They can also be connecting/disconnecting from the peer.
edited Feb 13 '15 at 19:12
muru
1
answered Oct 17 '14 at 13:53
kbenoitkbenoit
1,9271813
add a comment |
There's a few parameters to netstat that are useful for this :
-lor--listeningshows only the sockets currently listening for incoming connection.
-aor--allshows all sockets currently in use.
-tor--tcpshows the tcp sockets.
-uor--udpshows the udp sockets.
-nor--numericshows the hosts and ports as numbers, instead of resolving in dns and looking in /etc/services.
You use a mix of these to get what you want. To know which port numbers are currently in use, use one of these:
netstat -atn # For tcp
netstat -aun # For udp
netstat -atun # For both
In the output all port mentioned are in use either listening for incoming connection or connected to a peer** all others are closed. TCP and UDP ports are 16 bits wide (they go from 1-65535)
** They can also be connecting/disconnecting from the peer.
edited Feb 13 '15 at 19:12
muru
1
answered Oct 17 '14 at 13:53
kbenoitkbenoit
1,9271813
add a comment |
There's a few parameters to netstat that are useful for this :
-lor--listeningshows only the sockets currently listening for incoming connection.
-aor--allshows all sockets currently in use.
-tor--tcpshows the tcp sockets.
-uor--udpshows the udp sockets.
-nor--numericshows the hosts and ports as numbers, instead of resolving in dns and looking in /etc/services.
You use a mix of these to get what you want. To know which port numbers are currently in use, use one of these:
netstat -atn # For tcp
netstat -aun # For udp
netstat -atun # For both
In the output all port mentioned are in use either listening for incoming connection or connected to a peer** all others are closed. TCP and UDP ports are 16 bits wide (they go from 1-65535)
** They can also be connecting/disconnecting from the peer.
edited Feb 13 '15 at 19:12
muru
1
answered Oct 17 '14 at 13:53
kbenoitkbenoit
1,9271813
There's a few parameters to netstat that are useful for this :
-lor--listeningshows only the sockets currently listening for incoming connection.
-aor--allshows all sockets currently in use.
-tor--tcpshows the tcp sockets.
-uor--udpshows the udp sockets.
-nor--numericshows the hosts and ports as numbers, instead of resolving in dns and looking in /etc/services.
You use a mix of these to get what you want. To know which port numbers are currently in use, use one of these:
netstat -atn # For tcp
netstat -aun # For udp
netstat -atun # For both
In the output all port mentioned are in use either listening for incoming connection or connected to a peer** all others are closed. TCP and UDP ports are 16 bits wide (they go from 1-65535)
** They can also be connecting/disconnecting from the peer.
edited Feb 13 '15 at 19:12
muru
1
answered Oct 17 '14 at 13:53
kbenoitkbenoit
1,9271813
edited Feb 13 '15 at 19:12
muru
1
edited Feb 13 '15 at 19:12
muru
1
edited Feb 13 '15 at 19:12
muru
1
1
answered Oct 17 '14 at 13:53
kbenoitkbenoit
1,9271813
answered Oct 17 '14 at 13:53
kbenoitkbenoit
1,9271813
answered Oct 17 '14 at 13:53
kbenoitkbenoit
1,9271813
1,9271813
add a comment |
add a comment |
You can use this command:
netstat -tulnp | grep <port no>
If it shows some process its used. Its closed(not used) if there is no output.
edited Sep 16 '15 at 12:29
Community♦
1
answered Oct 17 '14 at 12:45
kashminderkashminder
1,060815
add a comment |
You can use this command:
netstat -tulnp | grep <port no>
If it shows some process its used. Its closed(not used) if there is no output.
edited Sep 16 '15 at 12:29
Community♦
1
answered Oct 17 '14 at 12:45
kashminderkashminder
1,060815
add a comment |
You can use this command:
netstat -tulnp | grep <port no>
If it shows some process its used. Its closed(not used) if there is no output.
edited Sep 16 '15 at 12:29
Community♦
1
answered Oct 17 '14 at 12:45
kashminderkashminder
1,060815
You can use this command:
netstat -tulnp | grep <port no>
If it shows some process its used. Its closed(not used) if there is no output.
edited Sep 16 '15 at 12:29
Community♦
1
answered Oct 17 '14 at 12:45
kashminderkashminder
1,060815
edited Sep 16 '15 at 12:29
Community♦
1
edited Sep 16 '15 at 12:29
Community♦
1
edited Sep 16 '15 at 12:29
Community♦
1
1
answered Oct 17 '14 at 12:45
kashminderkashminder
1,060815
answered Oct 17 '14 at 12:45
kashminderkashminder
1,060815
answered Oct 17 '14 at 12:45
kashminderkashminder
1,060815
1,060815
add a comment |
add a comment |
Another alternative command line easy to use to find out which process is using a port:
lsof -n -i4TCP:$PORT | grep LISTEN
I added the next function in my .bash_profile,
function pslisten {
echo `lsof -n -i4TCP:$1 | grep LISTEN`
}
and now run "pslisten 5060" to see who is grabing my SIP port.
It's work with Apple Mac OS X too.
answered Mar 13 '15 at 7:22
Fernando SantucciFernando Santucci
8201714
add a comment |
Another alternative command line easy to use to find out which process is using a port:
lsof -n -i4TCP:$PORT | grep LISTEN
I added the next function in my .bash_profile,
function pslisten {
echo `lsof -n -i4TCP:$1 | grep LISTEN`
}
and now run "pslisten 5060" to see who is grabing my SIP port.
It's work with Apple Mac OS X too.
answered Mar 13 '15 at 7:22
Fernando SantucciFernando Santucci
8201714
add a comment |
Another alternative command line easy to use to find out which process is using a port:
lsof -n -i4TCP:$PORT | grep LISTEN
I added the next function in my .bash_profile,
function pslisten {
echo `lsof -n -i4TCP:$1 | grep LISTEN`
}
and now run "pslisten 5060" to see who is grabing my SIP port.
It's work with Apple Mac OS X too.
answered Mar 13 '15 at 7:22
Fernando SantucciFernando Santucci
8201714
Another alternative command line easy to use to find out which process is using a port:
lsof -n -i4TCP:$PORT | grep LISTEN
I added the next function in my .bash_profile,
function pslisten {
echo `lsof -n -i4TCP:$1 | grep LISTEN`
}
and now run "pslisten 5060" to see who is grabing my SIP port.
It's work with Apple Mac OS X too.
answered Mar 13 '15 at 7:22
Fernando SantucciFernando Santucci
8201714
answered Mar 13 '15 at 7:22
Fernando SantucciFernando Santucci
8201714
answered Mar 13 '15 at 7:22
Fernando SantucciFernando Santucci
8201714
answered Mar 13 '15 at 7:22
Fernando SantucciFernando Santucci
8201714
8201714
add a comment |
add a comment |
Is the port status "LISTENING" indicated that the port is opened?
Yes. It means that some service is listening to that port on your computer for incoming connection i.e. this port is open for establishing new connections.
Any port that are not shown in the output indicated that it's closed?
Yes. Remember netstat -a will show all active (listening) and passive (non-listening) connections i.e. the ports that are acting as both server (some services are listening to these ports for connections from a different machine/process) and established (connections are established on these ports regardless of the fact the host/a service can be a server or client)
All TCP and UDP ports belong to a category called sockets and there are a whole lot of those. To view socket info you can check man ss.
answered Oct 17 '14 at 13:53
heemaylheemayl
66.3k8139212
Thanks. you wrote that-ameans server and established. Does "server" means ports that are being listened at by some services? Does "established" mean ports where there are existing connections regardless of it is a client or server's port? Then what kinds of ports does-anot show?
– Tim
Aug 21 '18 at 19:28
I don't think the-aoption means "all active" sockets; it just means "all". netstat shows all active sockets by default, but leaves out the passive sockets (open, listening). By using the-aoption both active and passive sockets are shown.
– Egon Olieux
Sep 22 '18 at 8:28
@EgonOlieux Thanks. I stand corrected; edited the answer.
– heemayl
Sep 24 '18 at 20:20
@heemayl The second part of your answer is still not correct. A TCP socket in the "listening" state can never be a connection; it is not connected to anything, it is only listening. Listening TCP sockets are also called passive sockets because of this. If a client attempts to connect to a (listening) socket on a server, a new socket will be created on the server to establish a connection with the client. A socket which is part of an established connection is called an active socket.
– Egon Olieux
Sep 25 '18 at 20:37
add a comment |
Is the port status "LISTENING" indicated that the port is opened?
Yes. It means that some service is listening to that port on your computer for incoming connection i.e. this port is open for establishing new connections.
Any port that are not shown in the output indicated that it's closed?
Yes. Remember netstat -a will show all active (listening) and passive (non-listening) connections i.e. the ports that are acting as both server (some services are listening to these ports for connections from a different machine/process) and established (connections are established on these ports regardless of the fact the host/a service can be a server or client)
All TCP and UDP ports belong to a category called sockets and there are a whole lot of those. To view socket info you can check man ss.
answered Oct 17 '14 at 13:53
heemaylheemayl
66.3k8139212
Thanks. you wrote that-ameans server and established. Does "server" means ports that are being listened at by some services? Does "established" mean ports where there are existing connections regardless of it is a client or server's port? Then what kinds of ports does-anot show?
– Tim
Aug 21 '18 at 19:28
I don't think the-aoption means "all active" sockets; it just means "all". netstat shows all active sockets by default, but leaves out the passive sockets (open, listening). By using the-aoption both active and passive sockets are shown.
– Egon Olieux
Sep 22 '18 at 8:28
@EgonOlieux Thanks. I stand corrected; edited the answer.
– heemayl
Sep 24 '18 at 20:20
@heemayl The second part of your answer is still not correct. A TCP socket in the "listening" state can never be a connection; it is not connected to anything, it is only listening. Listening TCP sockets are also called passive sockets because of this. If a client attempts to connect to a (listening) socket on a server, a new socket will be created on the server to establish a connection with the client. A socket which is part of an established connection is called an active socket.
– Egon Olieux
Sep 25 '18 at 20:37
add a comment |
Is the port status "LISTENING" indicated that the port is opened?
Yes. It means that some service is listening to that port on your computer for incoming connection i.e. this port is open for establishing new connections.
Any port that are not shown in the output indicated that it's closed?
Yes. Remember netstat -a will show all active (listening) and passive (non-listening) connections i.e. the ports that are acting as both server (some services are listening to these ports for connections from a different machine/process) and established (connections are established on these ports regardless of the fact the host/a service can be a server or client)
All TCP and UDP ports belong to a category called sockets and there are a whole lot of those. To view socket info you can check man ss.
answered Oct 17 '14 at 13:53
heemaylheemayl
66.3k8139212
Is the port status "LISTENING" indicated that the port is opened?
Yes. It means that some service is listening to that port on your computer for incoming connection i.e. this port is open for establishing new connections.
Any port that are not shown in the output indicated that it's closed?
Yes. Remember netstat -a will show all active (listening) and passive (non-listening) connections i.e. the ports that are acting as both server (some services are listening to these ports for connections from a different machine/process) and established (connections are established on these ports regardless of the fact the host/a service can be a server or client)
All TCP and UDP ports belong to a category called sockets and there are a whole lot of those. To view socket info you can check man ss.
answered Oct 17 '14 at 13:53
heemaylheemayl
66.3k8139212
edited Sep 24 '18 at 20:19
answered Oct 17 '14 at 13:53
heemaylheemayl
66.3k8139212
answered Oct 17 '14 at 13:53
heemaylheemayl
66.3k8139212
answered Oct 17 '14 at 13:53
heemaylheemayl
66.3k8139212
66.3k8139212
Thanks. you wrote that-ameans server and established. Does "server" means ports that are being listened at by some services? Does "established" mean ports where there are existing connections regardless of it is a client or server's port? Then what kinds of ports does-anot show?
– Tim
Aug 21 '18 at 19:28
I don't think the-aoption means "all active" sockets; it just means "all". netstat shows all active sockets by default, but leaves out the passive sockets (open, listening). By using the-aoption both active and passive sockets are shown.
– Egon Olieux
Sep 22 '18 at 8:28
@EgonOlieux Thanks. I stand corrected; edited the answer.
– heemayl
Sep 24 '18 at 20:20
@heemayl The second part of your answer is still not correct. A TCP socket in the "listening" state can never be a connection; it is not connected to anything, it is only listening. Listening TCP sockets are also called passive sockets because of this. If a client attempts to connect to a (listening) socket on a server, a new socket will be created on the server to establish a connection with the client. A socket which is part of an established connection is called an active socket.
– Egon Olieux
Sep 25 '18 at 20:37
add a comment |
Thanks. you wrote that-ameans server and established. Does "server" means ports that are being listened at by some services? Does "established" mean ports where there are existing connections regardless of it is a client or server's port? Then what kinds of ports does-anot show?
– Tim
Aug 21 '18 at 19:28
I don't think the-aoption means "all active" sockets; it just means "all". netstat shows all active sockets by default, but leaves out the passive sockets (open, listening). By using the-aoption both active and passive sockets are shown.
– Egon Olieux
Sep 22 '18 at 8:28
@EgonOlieux Thanks. I stand corrected; edited the answer.
– heemayl
Sep 24 '18 at 20:20
@heemayl The second part of your answer is still not correct. A TCP socket in the "listening" state can never be a connection; it is not connected to anything, it is only listening. Listening TCP sockets are also called passive sockets because of this. If a client attempts to connect to a (listening) socket on a server, a new socket will be created on the server to establish a connection with the client. A socket which is part of an established connection is called an active socket.
– Egon Olieux
Sep 25 '18 at 20:37
Thanks. you wrote that
-a means server and established. Does "server" means ports that are being listened at by some services? Does "established" mean ports where there are existing connections regardless of it is a client or server's port? Then what kinds of ports does -a not show?– Tim
Aug 21 '18 at 19:28
Thanks. you wrote that
-a means server and established. Does "server" means ports that are being listened at by some services? Does "established" mean ports where there are existing connections regardless of it is a client or server's port? Then what kinds of ports does -a not show?– Tim
Aug 21 '18 at 19:28
I don't think the
-a option means "all active" sockets; it just means "all". netstat shows all active sockets by default, but leaves out the passive sockets (open, listening). By using the -a option both active and passive sockets are shown.– Egon Olieux
Sep 22 '18 at 8:28
I don't think the
-a option means "all active" sockets; it just means "all". netstat shows all active sockets by default, but leaves out the passive sockets (open, listening). By using the -a option both active and passive sockets are shown.– Egon Olieux
Sep 22 '18 at 8:28
@EgonOlieux Thanks. I stand corrected; edited the answer.
– heemayl
Sep 24 '18 at 20:20
@EgonOlieux Thanks. I stand corrected; edited the answer.
– heemayl
Sep 24 '18 at 20:20
@heemayl The second part of your answer is still not correct. A TCP socket in the "listening" state can never be a connection; it is not connected to anything, it is only listening. Listening TCP sockets are also called passive sockets because of this. If a client attempts to connect to a (listening) socket on a server, a new socket will be created on the server to establish a connection with the client. A socket which is part of an established connection is called an active socket.
– Egon Olieux
Sep 25 '18 at 20:37
@heemayl The second part of your answer is still not correct. A TCP socket in the "listening" state can never be a connection; it is not connected to anything, it is only listening. Listening TCP sockets are also called passive sockets because of this. If a client attempts to connect to a (listening) socket on a server, a new socket will be created on the server to establish a connection with the client. A socket which is part of an established connection is called an active socket.
– Egon Olieux
Sep 25 '18 at 20:37
add a comment |
Another option is ss. It's much easier to use....
The below command will only output a list of current listening sockets.
root@server:~# ss -l
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
u_dgr UNCONN 0 0 * 23353 * 23352
u_dgr UNCONN 0 0 * 568 * 362
u_dgr UNCONN 0 0 * 14836 * 14837
u_dgr UNCONN 0 0 * 20446 * 369
u_dgr UNCONN 0 0 * 22877 * 369
u_dgr UNCONN 0 0 * 504 * 347
u_dgr UNCONN 0 0 * 16298 * 369
u_dgr UNCONN 0 0 * 23343 * 369
u_dgr UNCONN 0 0 * 24125 * 369
u_dgr UNCONN 0 0 * 24617 * 369
u_dgr UNCONN 0 0 * 23352 * 23353
u_dgr UNCONN 0 0 * 23334 * 369
u_dgr UNCONN 0 0 * 17113 * 369
u_dgr UNCONN 0 0 * 16957 * 369
u_dgr UNCONN 0 0 * 14793 * 362
u_dgr UNCONN 0 0 * 23345 * 362
u_dgr UNCONN 0 0 * 24070 * 369
udp UNCONN 0 0 *:sunrpc *:*
udp UNCONN 0 0 *:981 *:*
udp UNCONN 0 0 :::sunrpc :::*
udp UNCONN 0 0 :::981 :::*
tcp LISTEN 0 128 127.0.0.1:85 *:*
tcp LISTEN 0 128 *:ssh *:*
tcp LISTEN 0 128 *:3128 *:*
tcp LISTEN 0 100 127.0.0.1:smtp *:*
tcp LISTEN 0 128 *:8006 *:*
tcp LISTEN 0 128 *:sunrpc *:*
tcp LISTEN 0 128 :::ssh :::*
tcp LISTEN 0 100 ::1:smtp :::*
tcp LISTEN 0 128 :::sunrpc :::*
answered Feb 5 '18 at 3:37
zeezee
1212
I did not know about this, thanks zee
– nick fox
Feb 8 '18 at 10:19
add a comment |
Another option is ss. It's much easier to use....
The below command will only output a list of current listening sockets.
root@server:~# ss -l
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
u_dgr UNCONN 0 0 * 23353 * 23352
u_dgr UNCONN 0 0 * 568 * 362
u_dgr UNCONN 0 0 * 14836 * 14837
u_dgr UNCONN 0 0 * 20446 * 369
u_dgr UNCONN 0 0 * 22877 * 369
u_dgr UNCONN 0 0 * 504 * 347
u_dgr UNCONN 0 0 * 16298 * 369
u_dgr UNCONN 0 0 * 23343 * 369
u_dgr UNCONN 0 0 * 24125 * 369
u_dgr UNCONN 0 0 * 24617 * 369
u_dgr UNCONN 0 0 * 23352 * 23353
u_dgr UNCONN 0 0 * 23334 * 369
u_dgr UNCONN 0 0 * 17113 * 369
u_dgr UNCONN 0 0 * 16957 * 369
u_dgr UNCONN 0 0 * 14793 * 362
u_dgr UNCONN 0 0 * 23345 * 362
u_dgr UNCONN 0 0 * 24070 * 369
udp UNCONN 0 0 *:sunrpc *:*
udp UNCONN 0 0 *:981 *:*
udp UNCONN 0 0 :::sunrpc :::*
udp UNCONN 0 0 :::981 :::*
tcp LISTEN 0 128 127.0.0.1:85 *:*
tcp LISTEN 0 128 *:ssh *:*
tcp LISTEN 0 128 *:3128 *:*
tcp LISTEN 0 100 127.0.0.1:smtp *:*
tcp LISTEN 0 128 *:8006 *:*
tcp LISTEN 0 128 *:sunrpc *:*
tcp LISTEN 0 128 :::ssh :::*
tcp LISTEN 0 100 ::1:smtp :::*
tcp LISTEN 0 128 :::sunrpc :::*
answered Feb 5 '18 at 3:37
zeezee
1212
I did not know about this, thanks zee
– nick fox
Feb 8 '18 at 10:19
add a comment |
Another option is ss. It's much easier to use....
The below command will only output a list of current listening sockets.
root@server:~# ss -l
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
u_dgr UNCONN 0 0 * 23353 * 23352
u_dgr UNCONN 0 0 * 568 * 362
u_dgr UNCONN 0 0 * 14836 * 14837
u_dgr UNCONN 0 0 * 20446 * 369
u_dgr UNCONN 0 0 * 22877 * 369
u_dgr UNCONN 0 0 * 504 * 347
u_dgr UNCONN 0 0 * 16298 * 369
u_dgr UNCONN 0 0 * 23343 * 369
u_dgr UNCONN 0 0 * 24125 * 369
u_dgr UNCONN 0 0 * 24617 * 369
u_dgr UNCONN 0 0 * 23352 * 23353
u_dgr UNCONN 0 0 * 23334 * 369
u_dgr UNCONN 0 0 * 17113 * 369
u_dgr UNCONN 0 0 * 16957 * 369
u_dgr UNCONN 0 0 * 14793 * 362
u_dgr UNCONN 0 0 * 23345 * 362
u_dgr UNCONN 0 0 * 24070 * 369
udp UNCONN 0 0 *:sunrpc *:*
udp UNCONN 0 0 *:981 *:*
udp UNCONN 0 0 :::sunrpc :::*
udp UNCONN 0 0 :::981 :::*
tcp LISTEN 0 128 127.0.0.1:85 *:*
tcp LISTEN 0 128 *:ssh *:*
tcp LISTEN 0 128 *:3128 *:*
tcp LISTEN 0 100 127.0.0.1:smtp *:*
tcp LISTEN 0 128 *:8006 *:*
tcp LISTEN 0 128 *:sunrpc *:*
tcp LISTEN 0 128 :::ssh :::*
tcp LISTEN 0 100 ::1:smtp :::*
tcp LISTEN 0 128 :::sunrpc :::*
answered Feb 5 '18 at 3:37
zeezee
1212
Another option is ss. It's much easier to use....
The below command will only output a list of current listening sockets.
root@server:~# ss -l
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
u_dgr UNCONN 0 0 * 23353 * 23352
u_dgr UNCONN 0 0 * 568 * 362
u_dgr UNCONN 0 0 * 14836 * 14837
u_dgr UNCONN 0 0 * 20446 * 369
u_dgr UNCONN 0 0 * 22877 * 369
u_dgr UNCONN 0 0 * 504 * 347
u_dgr UNCONN 0 0 * 16298 * 369
u_dgr UNCONN 0 0 * 23343 * 369
u_dgr UNCONN 0 0 * 24125 * 369
u_dgr UNCONN 0 0 * 24617 * 369
u_dgr UNCONN 0 0 * 23352 * 23353
u_dgr UNCONN 0 0 * 23334 * 369
u_dgr UNCONN 0 0 * 17113 * 369
u_dgr UNCONN 0 0 * 16957 * 369
u_dgr UNCONN 0 0 * 14793 * 362
u_dgr UNCONN 0 0 * 23345 * 362
u_dgr UNCONN 0 0 * 24070 * 369
udp UNCONN 0 0 *:sunrpc *:*
udp UNCONN 0 0 *:981 *:*
udp UNCONN 0 0 :::sunrpc :::*
udp UNCONN 0 0 :::981 :::*
tcp LISTEN 0 128 127.0.0.1:85 *:*
tcp LISTEN 0 128 *:ssh *:*
tcp LISTEN 0 128 *:3128 *:*
tcp LISTEN 0 100 127.0.0.1:smtp *:*
tcp LISTEN 0 128 *:8006 *:*
tcp LISTEN 0 128 *:sunrpc *:*
tcp LISTEN 0 128 :::ssh :::*
tcp LISTEN 0 100 ::1:smtp :::*
tcp LISTEN 0 128 :::sunrpc :::*
answered Feb 5 '18 at 3:37
zeezee
1212
answered Feb 5 '18 at 3:37
zeezee
1212
answered Feb 5 '18 at 3:37
zeezee
1212
answered Feb 5 '18 at 3:37
zeezee
1212
1212
I did not know about this, thanks zee
– nick fox
Feb 8 '18 at 10:19
add a comment |
I did not know about this, thanks zee
– nick fox
Feb 8 '18 at 10:19
I did not know about this, thanks zee
– nick fox
Feb 8 '18 at 10:19
I did not know about this, thanks zee
– nick fox
Feb 8 '18 at 10:19
add a comment |
Or this might help by using watch, then play around with what you want to see.
sudo watch -d -n0 "netstat -atnp | grep ESTA"
sudo watch -d -n0 "netstat -tulnp | grep ESTA"
answered Jan 4 '17 at 11:57
Ian CroasdellIan Croasdell
192
1
-a conflicts with -l, -a grabs all whether ESTABLISHED or LISTENING, and -l just grabs LISTENING, so in reality it is '-ltnp' tcp, '-lunp' udp or '-ltunp' tcp+udp
– ModerateJavaScriptDev
Jul 2 '17 at 23:31
add a comment |
Or this might help by using watch, then play around with what you want to see.
sudo watch -d -n0 "netstat -atnp | grep ESTA"
sudo watch -d -n0 "netstat -tulnp | grep ESTA"
answered Jan 4 '17 at 11:57
Ian CroasdellIan Croasdell
192
1
-a conflicts with -l, -a grabs all whether ESTABLISHED or LISTENING, and -l just grabs LISTENING, so in reality it is '-ltnp' tcp, '-lunp' udp or '-ltunp' tcp+udp
– ModerateJavaScriptDev
Jul 2 '17 at 23:31
add a comment |
Or this might help by using watch, then play around with what you want to see.
sudo watch -d -n0 "netstat -atnp | grep ESTA"
sudo watch -d -n0 "netstat -tulnp | grep ESTA"
answered Jan 4 '17 at 11:57
Ian CroasdellIan Croasdell
192
Or this might help by using watch, then play around with what you want to see.
sudo watch -d -n0 "netstat -atnp | grep ESTA"
sudo watch -d -n0 "netstat -tulnp | grep ESTA"
answered Jan 4 '17 at 11:57
Ian CroasdellIan Croasdell
192
edited Jul 23 '17 at 21:54
answered Jan 4 '17 at 11:57
Ian CroasdellIan Croasdell
192
answered Jan 4 '17 at 11:57
Ian CroasdellIan Croasdell
192
answered Jan 4 '17 at 11:57
Ian CroasdellIan Croasdell
192
192
1
-a conflicts with -l, -a grabs all whether ESTABLISHED or LISTENING, and -l just grabs LISTENING, so in reality it is '-ltnp' tcp, '-lunp' udp or '-ltunp' tcp+udp
– ModerateJavaScriptDev
Jul 2 '17 at 23:31
add a comment |
1
-a conflicts with -l, -a grabs all whether ESTABLISHED or LISTENING, and -l just grabs LISTENING, so in reality it is '-ltnp' tcp, '-lunp' udp or '-ltunp' tcp+udp
– ModerateJavaScriptDev
Jul 2 '17 at 23:31
1
1
-a conflicts with -l, -a grabs all whether ESTABLISHED or LISTENING, and -l just grabs LISTENING, so in reality it is '-ltnp' tcp, '-lunp' udp or '-ltunp' tcp+udp
– ModerateJavaScriptDev
Jul 2 '17 at 23:31
-a conflicts with -l, -a grabs all whether ESTABLISHED or LISTENING, and -l just grabs LISTENING, so in reality it is '-ltnp' tcp, '-lunp' udp or '-ltunp' tcp+udp
– ModerateJavaScriptDev
Jul 2 '17 at 23:31
add a comment |
Actually there is a better way to see what ports you have open. The issue with netstat or lsof is that they query network stack and actually do not connect to the machine but instead trying to see what is running on the system. The better approach is to use nmap like so:
nmap -sT -O localhost
To see open ports.
answered Feb 27 '18 at 0:45
DeveloperDeveloper
1133
add a comment |
Actually there is a better way to see what ports you have open. The issue with netstat or lsof is that they query network stack and actually do not connect to the machine but instead trying to see what is running on the system. The better approach is to use nmap like so:
nmap -sT -O localhost
To see open ports.
answered Feb 27 '18 at 0:45
DeveloperDeveloper
1133
add a comment |
Actually there is a better way to see what ports you have open. The issue with netstat or lsof is that they query network stack and actually do not connect to the machine but instead trying to see what is running on the system. The better approach is to use nmap like so:
nmap -sT -O localhost
To see open ports.
answered Feb 27 '18 at 0:45
DeveloperDeveloper
1133
Actually there is a better way to see what ports you have open. The issue with netstat or lsof is that they query network stack and actually do not connect to the machine but instead trying to see what is running on the system. The better approach is to use nmap like so:
nmap -sT -O localhost
To see open ports.
answered Feb 27 '18 at 0:45
DeveloperDeveloper
1133
answered Feb 27 '18 at 0:45
DeveloperDeveloper
1133
answered Feb 27 '18 at 0:45
DeveloperDeveloper
1133
answered Feb 27 '18 at 0:45
DeveloperDeveloper
1133
1133
add a comment |
add a comment |
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Check this post on AskUbuntu!.
– Justgivemeaname
Oct 17 '14 at 12:46
2
@Justgivemeaname:
nmapis a tool to check for open ports on another host. If you can runnetstaton a machine, it's much faster and reliable to use it.– David Foerster
Oct 17 '14 at 14:20
@DavidFoerster: Didn't know about
netstat, so I learned that. It says in the link that it should be used from another host, though. Thanks!– Justgivemeaname
Oct 17 '14 at 14:38
3
Possible duplicate of How can I see what ports are open on my machine?
– Dan Dascalescu
Jan 17 '17 at 20:32