UDP source port

[slaskbrev1]

Hi.
Im sending data over a SOCK_DGRAM socket, is it possible to define
what source port my program will use?
I guess one alternative is to craft the UDP header by myself, what
type of socket would I use then? Do I have to craft the IP header
aswell and use SOCK_RAW?

Thanks

 

[Antoninus Twink]

Im sending data over a SOCK_DGRAM socket, is it possible to define
what source port my program will use?

Yes - just set the sin_port field of the struct sockaddr *address
argument you give to bind(). (The default value of 0 for sin_port just
means "pick any available port".)

 

[slaskbrev1]

Yes - just set the sin_port field of the struct sockaddr *address
argument you give to bind(). (The default value of 0 for sin_port just
means "pick any available port".)

Thanks. It bothers me I didnt figure that out myself.

 

[Keith Thompson]

Im sending data over a SOCK_DGRAM socket, is it possible to define
what source port my program will use?
I guess one alternative is to craft the UDP header by myself, what
type of socket would I use then? Do I have to craft the IP header
aswell and use SOCK_RAW?

Please ask in a newsgroup that discusses your operating system,
perhaps comp.unix.programmer or one of the Windows groups.

 

[ionic]

Call bind() right after socket(), specify your local port and NIC
adapter in sockaddr_in.