Which ephemeral ports are used with raw sockets

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Referring to How source ports get assigned, I do know, how the local port is determined. (=> Random free ephemeral port).

However, why does my raw socket using socket(AF_INET, SOCK_RAW, IPPROTO_TCP) get port 6 assigned?

ss -lnp shows: tcp UNCONN 0 0 0.0.0.0:6 0.0.0.0:* users:(("exe",pid=13164,fd=5))

Do I create the socket incorrectly (because IPPROTO_TCP is defined with =6 in linux/in.h)? Or are RAW_SOCKETS defaulted to port 6 if available?

I am Using Ubuntu 4.15 if that's important.

asked Sep 19 at 11:02

Joel

1216

Raw sockets are not port specific, but protocol specific (they can be used to implement new IP protocols in user space) so I strongly suspect the protocol is encoded in what ss shows as the port. It's easy to test: Use a different protocol (including unassigned numbers) and have a look at what ss shows. Or use nc etc. to send a few TCP packets to/from unrelated ports and see if you receive them.
â€“Â dirkt
Sep 19 at 11:15

If I understood correctly, the 6 in ss just seem to tell me, that I used IPPROTO_TCP... yes. Using socket(AF_INET, SOCK_RAW, 123) ss outputs ??? UNCONN 0 0 0.0.0.0:123 0.0.0.0:* users:(("exe",pid=10039,fd=3)) so it makes sense. I'll write this as an answer.
â€“Â Joel
Sep 19 at 11:25

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up vote
0
down vote

favorite

Referring to How source ports get assigned, I do know, how the local port is determined. (=> Random free ephemeral port).

However, why does my raw socket using socket(AF_INET, SOCK_RAW, IPPROTO_TCP) get port 6 assigned?

ss -lnp shows: tcp UNCONN 0 0 0.0.0.0:6 0.0.0.0:* users:(("exe",pid=13164,fd=5))

Do I create the socket incorrectly (because IPPROTO_TCP is defined with =6 in linux/in.h)? Or are RAW_SOCKETS defaulted to port 6 if available?

I am Using Ubuntu 4.15 if that's important.

asked Sep 19 at 11:02

Joel

1216

Raw sockets are not port specific, but protocol specific (they can be used to implement new IP protocols in user space) so I strongly suspect the protocol is encoded in what ss shows as the port. It's easy to test: Use a different protocol (including unassigned numbers) and have a look at what ss shows. Or use nc etc. to send a few TCP packets to/from unrelated ports and see if you receive them.
â€“Â dirkt
Sep 19 at 11:15

If I understood correctly, the 6 in ss just seem to tell me, that I used IPPROTO_TCP... yes. Using socket(AF_INET, SOCK_RAW, 123) ss outputs ??? UNCONN 0 0 0.0.0.0:123 0.0.0.0:* users:(("exe",pid=10039,fd=3)) so it makes sense. I'll write this as an answer.
â€“Â Joel
Sep 19 at 11:25

add a commentÂ |Â

up vote
0
down vote

favorite

Referring to How source ports get assigned, I do know, how the local port is determined. (=> Random free ephemeral port).

However, why does my raw socket using socket(AF_INET, SOCK_RAW, IPPROTO_TCP) get port 6 assigned?

ss -lnp shows: tcp UNCONN 0 0 0.0.0.0:6 0.0.0.0:* users:(("exe",pid=13164,fd=5))

Do I create the socket incorrectly (because IPPROTO_TCP is defined with =6 in linux/in.h)? Or are RAW_SOCKETS defaulted to port 6 if available?

I am Using Ubuntu 4.15 if that's important.

asked Sep 19 at 11:02

Joel

1216

Referring to How source ports get assigned, I do know, how the local port is determined. (=> Random free ephemeral port).

However, why does my raw socket using socket(AF_INET, SOCK_RAW, IPPROTO_TCP) get port 6 assigned?

ss -lnp shows: tcp UNCONN 0 0 0.0.0.0:6 0.0.0.0:* users:(("exe",pid=13164,fd=5))

Do I create the socket incorrectly (because IPPROTO_TCP is defined with =6 in linux/in.h)? Or are RAW_SOCKETS defaulted to port 6 if available?

I am Using Ubuntu 4.15 if that's important.

networking kernel port

asked Sep 19 at 11:02

Joel

1216

asked Sep 19 at 11:02

Joel

1216

asked Sep 19 at 11:02

Joel

1216

asked Sep 19 at 11:02

Joel

1216

asked Sep 19 at 11:02

Joel

1216

Raw sockets are not port specific, but protocol specific (they can be used to implement new IP protocols in user space) so I strongly suspect the protocol is encoded in what ss shows as the port. It's easy to test: Use a different protocol (including unassigned numbers) and have a look at what ss shows. Or use nc etc. to send a few TCP packets to/from unrelated ports and see if you receive them.
â€“Â dirkt
Sep 19 at 11:15

If I understood correctly, the 6 in ss just seem to tell me, that I used IPPROTO_TCP... yes. Using socket(AF_INET, SOCK_RAW, 123) ss outputs ??? UNCONN 0 0 0.0.0.0:123 0.0.0.0:* users:(("exe",pid=10039,fd=3)) so it makes sense. I'll write this as an answer.
â€“Â Joel
Sep 19 at 11:25

add a commentÂ |Â

Raw sockets are not port specific, but protocol specific (they can be used to implement new IP protocols in user space) so I strongly suspect the protocol is encoded in what ss shows as the port. It's easy to test: Use a different protocol (including unassigned numbers) and have a look at what ss shows. Or use nc etc. to send a few TCP packets to/from unrelated ports and see if you receive them.
â€“Â dirkt
Sep 19 at 11:15

If I understood correctly, the 6 in ss just seem to tell me, that I used IPPROTO_TCP... yes. Using socket(AF_INET, SOCK_RAW, 123) ss outputs ??? UNCONN 0 0 0.0.0.0:123 0.0.0.0:* users:(("exe",pid=10039,fd=3)) so it makes sense. I'll write this as an answer.
â€“Â Joel
Sep 19 at 11:25

Raw sockets are not port specific, but protocol specific (they can be used to implement new IP protocols in user space) so I strongly suspect the protocol is encoded in what ss shows as the port. It's easy to test: Use a different protocol (including unassigned numbers) and have a look at what ss shows. Or use nc etc. to send a few TCP packets to/from unrelated ports and see if you receive them.
â€“Â dirkt
Sep 19 at 11:15

If I understood correctly, the 6 in ss just seem to tell me, that I used IPPROTO_TCP... yes. Using socket(AF_INET, SOCK_RAW, 123) ss outputs ??? UNCONN 0 0 0.0.0.0:123 0.0.0.0:* users:(("exe",pid=10039,fd=3)) so it makes sense. I'll write this as an answer.
â€“Â Joel
Sep 19 at 11:25

add a commentÂ |Â

1 Answer
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As @dirkt commented, the socket is not-port bound and displays the protocol aftert the local IP instead of the port (which is not there obviously).

using socket(AF_INET, SOCK_RAW, 123), ss outputs ??? UNCONN 0 0 0.0.0.0:123 0.0.0.0:* users:(("exe",pid=10039,fd=3))

Also, testing with other numbers as the third argument to socket(), ss shows that as the local port.

answered Sep 19 at 11:29

Joel

1216

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1 Answer
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active

oldest

votes

up vote
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down vote

accepted

As @dirkt commented, the socket is not-port bound and displays the protocol aftert the local IP instead of the port (which is not there obviously).

using socket(AF_INET, SOCK_RAW, 123), ss outputs ??? UNCONN 0 0 0.0.0.0:123 0.0.0.0:* users:(("exe",pid=10039,fd=3))

Also, testing with other numbers as the third argument to socket(), ss shows that as the local port.

answered Sep 19 at 11:29

Joel

1216

add a commentÂ |Â

up vote
1
down vote

accepted

As @dirkt commented, the socket is not-port bound and displays the protocol aftert the local IP instead of the port (which is not there obviously).

using socket(AF_INET, SOCK_RAW, 123), ss outputs ??? UNCONN 0 0 0.0.0.0:123 0.0.0.0:* users:(("exe",pid=10039,fd=3))

Also, testing with other numbers as the third argument to socket(), ss shows that as the local port.

answered Sep 19 at 11:29

Joel

1216

add a commentÂ |Â

up vote
1
down vote

accepted

As @dirkt commented, the socket is not-port bound and displays the protocol aftert the local IP instead of the port (which is not there obviously).

using socket(AF_INET, SOCK_RAW, 123), ss outputs ??? UNCONN 0 0 0.0.0.0:123 0.0.0.0:* users:(("exe",pid=10039,fd=3))

Also, testing with other numbers as the third argument to socket(), ss shows that as the local port.

answered Sep 19 at 11:29

Joel

1216

As @dirkt commented, the socket is not-port bound and displays the protocol aftert the local IP instead of the port (which is not there obviously).

using socket(AF_INET, SOCK_RAW, 123), ss outputs ??? UNCONN 0 0 0.0.0.0:123 0.0.0.0:* users:(("exe",pid=10039,fd=3))

Also, testing with other numbers as the third argument to socket(), ss shows that as the local port.

answered Sep 19 at 11:29

Joel

1216

answered Sep 19 at 11:29

Joel

1216

answered Sep 19 at 11:29

Joel

1216

answered Sep 19 at 11:29

Joel

1216

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