* Creating a routing program - the basics @ 2007-10-23 10:44 Mateus Interciso 2007-10-23 11:15 ` Steve Graegert 0 siblings, 1 reply; 6+ messages in thread From: Mateus Interciso @ 2007-10-23 10:44 UTC (permalink / raw) To: linux-c-programming Hello, I'm currently on university, and for my graduation paper, I'll be implementing a routing algorythm, by hand, in C. The routing algorythm itself is not easy, but one of the starting parts of it, is to find a way of discovering the MAC that it is currently connected to, maybe is bether if I draw, since I'm not really that good in english: [PC with n NICs]-----(n cables)---->[n PCs] I have full control of the first PC, of course, since is the one I'm implementing the router, so I do know the MAC of it, but how to discover the MAC on the other end of the n lines, so I can start sending packets? Anyone could help me impĺementing this exact thing? I think I got the theory right, but I have no clue how to start programing. Thanks a lot. Mateus - To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Creating a routing program - the basics 2007-10-23 10:44 Creating a routing program - the basics Mateus Interciso @ 2007-10-23 11:15 ` Steve Graegert 2007-10-23 12:11 ` Mateus Interciso 0 siblings, 1 reply; 6+ messages in thread From: Steve Graegert @ 2007-10-23 11:15 UTC (permalink / raw) To: Mateus Interciso; +Cc: linux-c-programming On 10/23/07, Mateus Interciso <p.zarnick@gmail.com> wrote: > Hello, I'm currently on university, and for my graduation paper, I'll be > implementing a routing algorythm, by hand, in C. > The routing algorythm itself is not easy, but one of the starting parts > of it, is to find a way of discovering the MAC that it is currently > connected to, maybe is bether if I draw, since I'm not really that good > in english: > > [PC with n NICs]-----(n cables)---->[n PCs] > > I have full control of the first PC, of course, since is the one I'm > implementing the router, so I do know the MAC of it, but how to discover > the MAC on the other end of the n lines, so I can start sending packets? Probably this is a starting point: (not tested) ___ BEGIN SOURCE ___ #include <iostream> #include <stdio.h> #include <netdb.h> #include <netinet/if_ether.h> int read_mac(void) { int sock, sockfd, n, cnt; char buffer[2048]; unsigned char *iphead, *ethhead; struct ether_addr ether; if ((sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP))) < 0) { perror("socket"); exit(1); } while (1) { if ((n = recvfrom(sock, buffer, 2048, 0, NULL, NULL)) == -1) { perror("recvfrom"); close(sock); exit(1); } ethhead = (unsigned char *)buffer; if (ethhead != NULL) { iphead = (unsigned char *)(buffer + 14); // Skip Ethernet header printf("Peer MAC: " "%02x:%02x:%02x:%02x:%02x:%02x\n", ethhead[0], ethhead[1], ethhead[2], ethhead[3], ethhead[4], ethhead[5]); printf("Source MAC: " "%02x:%02x:%02x:%02x:%02x:%02x\n", ethhead[6], ethhead[7], ethhead[8], ethhead[9], ethhead[10], ethhead[11]); if (*iphead == 0x45) { // Check for IPv4, no options present printf("Peer IP: %d.%d.%d.%d\n", iphead[12], iphead[13], iphead[14], iphead[15]); printf("Source IP: %d.%d.%d.%d\n", iphead[16], iphead[17], iphead[18], iphead[19]); printf("Protocol (UDP = 11): %02x Hex\n", iphead[9]); } } } return 0; } int main(int argc, char **argv) { read_mac(); return EXIT_SUCCESS; } ___ END SOURCE ___ Honestly, you should make yourself acquainted with low-level network programming. Otherwise you'll be asking a lot of theses questions in the future. Anyway, hope this helps. \Steve -- Steve Grägert DigitalEther.de - To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Creating a routing program - the basics 2007-10-23 11:15 ` Steve Graegert @ 2007-10-23 12:11 ` Mateus Interciso 2007-10-23 13:56 ` Steve Graegert 0 siblings, 1 reply; 6+ messages in thread From: Mateus Interciso @ 2007-10-23 12:11 UTC (permalink / raw) To: linux-c-programming On Tue, 23 Oct 2007 13:15:11 +0200, Steve Graegert wrote: > On 10/23/07, Mateus Interciso <p.zarnick@gmail.com> wrote: >> Hello, I'm currently on university, and for my graduation paper, I'll >> be implementing a routing algorythm, by hand, in C. The routing >> algorythm itself is not easy, but one of the starting parts of it, is >> to find a way of discovering the MAC that it is currently connected to, >> maybe is bether if I draw, since I'm not really that good in english: >> >> [PC with n NICs]-----(n cables)---->[n PCs] >> >> I have full control of the first PC, of course, since is the one I'm >> implementing the router, so I do know the MAC of it, but how to >> discover the MAC on the other end of the n lines, so I can start >> sending packets? > > Probably this is a starting point: (not tested) > > ___ BEGIN SOURCE ___ > > #include <iostream> > #include <stdio.h> > #include <netdb.h> > #include <netinet/if_ether.h> > > int read_mac(void) { > int sock, sockfd, n, cnt; > char buffer[2048]; > unsigned char *iphead, *ethhead; > struct ether_addr ether; > > if ((sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP))) < 0) { > perror("socket"); > exit(1); > } > > while (1) { > if ((n = recvfrom(sock, buffer, 2048, 0, NULL, NULL)) == -1) { > perror("recvfrom"); > close(sock); > exit(1); > } > > ethhead = (unsigned char *)buffer; > > if (ethhead != NULL) { > iphead = (unsigned char *)(buffer + 14); // Skip Ethernet header > printf("Peer MAC: " > "%02x:%02x:%02x:%02x:%02x:%02x\n", > ethhead[0], ethhead[1], ethhead[2], > ethhead[3], ethhead[4], ethhead[5]); > printf("Source MAC: " > "%02x:%02x:%02x:%02x:%02x:%02x\n", > ethhead[6], ethhead[7], ethhead[8], > ethhead[9], ethhead[10], ethhead[11]); > > if (*iphead == 0x45) { // Check for IPv4, no options present > printf("Peer IP: %d.%d.%d.%d\n", > iphead[12], iphead[13], > iphead[14], iphead[15]); > printf("Source IP: %d.%d.%d.%d\n", > iphead[16], iphead[17], > iphead[18], iphead[19]); > printf("Protocol (UDP = 11): %02x Hex\n", iphead[9]); > } > } > } > > return 0; > } > > > int main(int argc, char **argv) { > read_mac(); > return EXIT_SUCCESS; > } > > ___ END SOURCE ___ > > Honestly, you should make yourself acquainted with low-level network > programming. Otherwise you'll be asking a lot of theses questions in > the future. Anyway, hope this helps. > > \Steve > > -- > > Steve Grägert > DigitalEther.de > - > To unsubscribe from this list: send the line "unsubscribe > linux-c-programming" in the body of a message to > majordomo@vger.kernel.org More majordomo info at > http://vger.kernel.org/majordomo-info.html Thank you, this will help. Do you have any book/site where I can take a deep look into how to do that stuff? MAteus - To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Creating a routing program - the basics 2007-10-23 12:11 ` Mateus Interciso @ 2007-10-23 13:56 ` Steve Graegert 2007-10-23 14:13 ` Mateus Interciso 0 siblings, 1 reply; 6+ messages in thread From: Steve Graegert @ 2007-10-23 13:56 UTC (permalink / raw) To: Mateus Interciso; +Cc: linux-c-programming On 10/23/07, Mateus Interciso <p.zarnick@gmail.com> wrote: > On Tue, 23 Oct 2007 13:15:11 +0200, Steve Graegert wrote: > > > On 10/23/07, Mateus Interciso <p.zarnick@gmail.com> wrote: > >> Hello, I'm currently on university, and for my graduation paper, I'll > >> be implementing a routing algorythm, by hand, in C. The routing > >> algorythm itself is not easy, but one of the starting parts of it, is > >> to find a way of discovering the MAC that it is currently connected to, > >> maybe is bether if I draw, since I'm not really that good in english: > >> > >> [PC with n NICs]-----(n cables)---->[n PCs] > >> > >> I have full control of the first PC, of course, since is the one I'm > >> implementing the router, so I do know the MAC of it, but how to > >> discover the MAC on the other end of the n lines, so I can start > >> sending packets? > > > > Probably this is a starting point: (not tested) > > > > ___ BEGIN SOURCE ___ > > > > #include <iostream> > > #include <stdio.h> > > #include <netdb.h> > > #include <netinet/if_ether.h> > > > > int read_mac(void) { > > int sock, sockfd, n, cnt; > > char buffer[2048]; > > unsigned char *iphead, *ethhead; > > struct ether_addr ether; > > > > if ((sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP))) < 0) { > > perror("socket"); > > exit(1); > > } > > > > while (1) { > > if ((n = recvfrom(sock, buffer, 2048, 0, NULL, NULL)) == > -1) { > > perror("recvfrom"); > > close(sock); > > exit(1); > > } > > > > ethhead = (unsigned char *)buffer; > > > > if (ethhead != NULL) { > > iphead = (unsigned char *)(buffer + 14); // Skip > Ethernet header > > printf("Peer MAC: " > > "%02x:%02x:%02x:%02x:%02x:%02x\n", > > ethhead[0], ethhead[1], ethhead[2], > > ethhead[3], ethhead[4], ethhead[5]); > > printf("Source MAC: " > > "%02x:%02x:%02x:%02x:%02x:%02x\n", > > ethhead[6], ethhead[7], ethhead[8], > > ethhead[9], ethhead[10], ethhead[11]); > > > > if (*iphead == 0x45) { // Check for IPv4, no > options present > > printf("Peer IP: %d.%d.%d.%d\n", > > iphead[12], iphead[13], > > iphead[14], iphead[15]); > > printf("Source IP: %d.%d.%d.%d\n", > > iphead[16], iphead[17], > > iphead[18], iphead[19]); > > printf("Protocol (UDP = 11): %02x Hex\n", > iphead[9]); > > } > > } > > } > > > > return 0; > > } > > > > > > int main(int argc, char **argv) { > > read_mac(); > > return EXIT_SUCCESS; > > } > > > > ___ END SOURCE ___ > > > > Honestly, you should make yourself acquainted with low-level network > > programming. Otherwise you'll be asking a lot of theses questions in > > the future. Anyway, hope this helps. > > > > \Steve > > > > -- > > > > Steve Grägert > > DigitalEther.de > > - > > To unsubscribe from this list: send the line "unsubscribe > > linux-c-programming" in the body of a message to > > majordomo@vger.kernel.org More majordomo info at > > http://vger.kernel.org/majordomo-info.html > > Thank you, this will help. > Do you have any book/site where I can take a deep look into how to do > that stuff? I can't make any recommendations beyond the well-known programming books like Steven's UNP and O'Reilly's "Understanding the Linux Kernel". Additionally, you may find Sams Publishing 's "Linux(R) Socket Programming" (0672319357) useful. \Steve -- Steve Grägert DigitalEther.de - To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Creating a routing program - the basics 2007-10-23 13:56 ` Steve Graegert @ 2007-10-23 14:13 ` Mateus Interciso 2007-11-02 18:28 ` J. 0 siblings, 1 reply; 6+ messages in thread From: Mateus Interciso @ 2007-10-23 14:13 UTC (permalink / raw) To: linux-c-programming On Tue, 23 Oct 2007 15:56:22 +0200, Steve Graegert wrote: > On 10/23/07, Mateus Interciso <p.zarnick@gmail.com> wrote: >> On Tue, 23 Oct 2007 13:15:11 +0200, Steve Graegert wrote: >> >> > On 10/23/07, Mateus Interciso <p.zarnick@gmail.com> wrote: >> >> Hello, I'm currently on university, and for my graduation paper, >> >> I'll be implementing a routing algorythm, by hand, in C. The routing >> >> algorythm itself is not easy, but one of the starting parts of it, >> >> is to find a way of discovering the MAC that it is currently >> >> connected to, maybe is bether if I draw, since I'm not really that >> >> good in english: >> >> >> >> [PC with n NICs]-----(n cables)---->[n PCs] >> >> >> >> I have full control of the first PC, of course, since is the one I'm >> >> implementing the router, so I do know the MAC of it, but how to >> >> discover the MAC on the other end of the n lines, so I can start >> >> sending packets? >> > >> > Probably this is a starting point: (not tested) >> > >> > ___ BEGIN SOURCE ___ >> > >> > #include <iostream> >> > #include <stdio.h> >> > #include <netdb.h> >> > #include <netinet/if_ether.h> >> > >> > int read_mac(void) { >> > int sock, sockfd, n, cnt; >> > char buffer[2048]; >> > unsigned char *iphead, *ethhead; >> > struct ether_addr ether; >> > >> > if ((sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP))) < 0) >> > { >> > perror("socket"); >> > exit(1); >> > } >> > >> > while (1) { >> > if ((n = recvfrom(sock, buffer, 2048, 0, NULL, NULL)) >> > == >> -1) { >> > perror("recvfrom"); >> > close(sock); >> > exit(1); >> > } >> > >> > ethhead = (unsigned char *)buffer; >> > >> > if (ethhead != NULL) { >> > iphead = (unsigned char *)(buffer + 14); // >> > Skip >> Ethernet header >> > printf("Peer MAC: " >> > "%02x:%02x:%02x:%02x:%02x:%02x\n", >> > ethhead[0], ethhead[1], ethhead[2], >> > ethhead[3], ethhead[4], ethhead[5]); >> > printf("Source MAC: " >> > "%02x:%02x:%02x:%02x:%02x:%02x\n", >> > ethhead[6], ethhead[7], ethhead[8], >> > ethhead[9], ethhead[10], ethhead[11]); >> > >> > if (*iphead == 0x45) { // Check for IPv4, no >> options present >> > printf("Peer IP: %d.%d.%d.%d\n", >> > iphead[12], iphead[13], >> > iphead[14], iphead[15]); >> > printf("Source IP: %d.%d.%d.%d\n", >> > iphead[16], iphead[17], >> > iphead[18], iphead[19]); >> > printf("Protocol (UDP = 11): %02x >> > Hex\n", >> iphead[9]); >> > } >> > } >> > } >> > >> > return 0; >> > } >> > >> > >> > int main(int argc, char **argv) { >> > read_mac(); >> > return EXIT_SUCCESS; >> > } >> > >> > ___ END SOURCE ___ >> > >> > Honestly, you should make yourself acquainted with low-level network >> > programming. Otherwise you'll be asking a lot of theses questions in >> > the future. Anyway, hope this helps. >> > >> > \Steve >> > >> > -- >> > >> > Steve Grägert >> > DigitalEther.de >> > - >> > To unsubscribe from this list: send the line "unsubscribe >> > linux-c-programming" in the body of a message to >> > majordomo@vger.kernel.org More majordomo info at >> > http://vger.kernel.org/majordomo-info.html >> >> Thank you, this will help. >> Do you have any book/site where I can take a deep look into how to do >> that stuff? > > I can't make any recommendations beyond the well-known programming books > like Steven's UNP and O'Reilly's "Understanding the Linux Kernel". > Additionally, you may find Sams Publishing 's "Linux(R) Socket > Programming" (0672319357) useful. > > \Steve > > -- > > Steve Grägert > DigitalEther.de > - > To unsubscribe from this list: send the line "unsubscribe > linux-c-programming" in the body of a message to > majordomo@vger.kernel.org More majordomo info at > http://vger.kernel.org/majordomo-info.html Thank you, I'll take a look at those books :D Mateus - To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Creating a routing program - the basics 2007-10-23 14:13 ` Mateus Interciso @ 2007-11-02 18:28 ` J. 0 siblings, 0 replies; 6+ messages in thread From: J. @ 2007-11-02 18:28 UTC (permalink / raw) To: linux-c-programming; +Cc: Mateus Interciso On Tue, 23 Oct 2007, Mateus Interciso wrote: > On Tue, 23 Oct 2007 15:56:22 +0200, Steve Graegert wrote: > > > On 10/23/07, Mateus Interciso <p.zarnick@gmail.com> wrote: > >> On Tue, 23 Oct 2007 13:15:11 +0200, Steve Graegert wrote: > >> > >> > On 10/23/07, Mateus Interciso <p.zarnick@gmail.com> wrote: > >> >> Hello, I'm currently on university, and for my graduation paper, > >> >> I'll be implementing a routing algorythm, by hand, in C. The routing > >> >> algorythm itself is not easy, but one of the starting parts of it, > >> >> is to find a way of discovering the MAC that it is currently > >> >> connected to, maybe is bether if I draw, since I'm not really that > >> >> good in english: > >> >> > >> >> [PC with n NICs]-----(n cables)---->[n PCs] > >> >> > >> >> I have full control of the first PC, of course, since is the one I'm > >> >> implementing the router, so I do know the MAC of it, but how to > >> >> discover the MAC on the other end of the n lines, so I can start > >> >> sending packets? > >> > > >> > Probably this is a starting point: (not tested) > >> > > >> > ___ BEGIN SOURCE ___ > >> > > >> > #include <iostream> > >> > #include <stdio.h> > >> > #include <netdb.h> > >> > #include <netinet/if_ether.h> > >> > > >> > int read_mac(void) { > >> > int sock, sockfd, n, cnt; > >> > char buffer[2048]; > >> > unsigned char *iphead, *ethhead; > >> > struct ether_addr ether; > >> > > >> > if ((sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP))) < 0) > >> > { > >> > perror("socket"); > >> > exit(1); > >> > } > >> > > >> > while (1) { > >> > if ((n = recvfrom(sock, buffer, 2048, 0, NULL, NULL)) > >> > == > >> -1) { > >> > perror("recvfrom"); > >> > close(sock); > >> > exit(1); > >> > } > >> > > >> > ethhead = (unsigned char *)buffer; > >> > > >> > if (ethhead != NULL) { > >> > iphead = (unsigned char *)(buffer + 14); // > >> > Skip > >> Ethernet header > >> > printf("Peer MAC: " > >> > "%02x:%02x:%02x:%02x:%02x:%02x\n", > >> > ethhead[0], ethhead[1], ethhead[2], > >> > ethhead[3], ethhead[4], ethhead[5]); > >> > printf("Source MAC: " > >> > "%02x:%02x:%02x:%02x:%02x:%02x\n", > >> > ethhead[6], ethhead[7], ethhead[8], > >> > ethhead[9], ethhead[10], ethhead[11]); > >> > > >> > if (*iphead == 0x45) { // Check for IPv4, no > >> options present > >> > printf("Peer IP: %d.%d.%d.%d\n", > >> > iphead[12], iphead[13], > >> > iphead[14], iphead[15]); > >> > printf("Source IP: %d.%d.%d.%d\n", > >> > iphead[16], iphead[17], > >> > iphead[18], iphead[19]); > >> > printf("Protocol (UDP = 11): %02x > >> > Hex\n", > >> iphead[9]); > >> > } > >> > } > >> > } > >> > > >> > return 0; > >> > } > >> > > >> > > >> > int main(int argc, char **argv) { > >> > read_mac(); > >> > return EXIT_SUCCESS; > >> > } > >> > > >> > ___ END SOURCE ___ > >> > > >> > Honestly, you should make yourself acquainted with low-level network > >> > programming. Otherwise you'll be asking a lot of theses questions in > >> > the future. Anyway, hope this helps. > >> > > >> > \Steve > >> > > >> > -- > >> > > >> > Steve Grägert > >> > DigitalEther.de > >> > - > >> > To unsubscribe from this list: send the line "unsubscribe > >> > linux-c-programming" in the body of a message to > >> > majordomo@vger.kernel.org More majordomo info at > >> > http://vger.kernel.org/majordomo-info.html > >> > >> Thank you, this will help. > >> Do you have any book/site where I can take a deep look into how to do > >> that stuff? > > > > I can't make any recommendations beyond the well-known programming books > > like Steven's UNP and O'Reilly's "Understanding the Linux Kernel". > > Additionally, you may find Sams Publishing 's "Linux(R) Socket > > Programming" (0672319357) useful. > > > > \Steve > > > > -- > > > > Steve Grägert > > DigitalEther.de > > - > > To unsubscribe from this list: send the line "unsubscribe > > linux-c-programming" in the body of a message to > > majordomo@vger.kernel.org More majordomo info at > > http://vger.kernel.org/majordomo-info.html > > Thank you, I'll take a look at those books :D > > Mateus Hi, I would most certainly in the first place go for the following books by Richard Stevens: # TCP/IP Illustrated, Volume 1: The Protocols, Addison-Wesley, 1994. # TCP/IP Illustrated, Volume 2: The Implementation, Addison-Wesley, 1995. # TCP/IP Illustrated, Volume 3: TCP for Transactions, HTTP, NNTP, and the UNIX Domain Protocols, Addison-Wesley, 1996. # UNIX Network Programming, Volume 1, Second Edition: Networking APIs: Sockets and XTI, Prentice Hall, 1998. # UNIX Network Programming, Volume 2, Second Edition: Interprocess Communications, Prentice Hall, 1999. for a complete list of Richard Steven's books: http://www.kohala.com/start/#books or amazon... Than the source-code of libpcap [tcpdump] is always very helpful. Maybe also another suggestion; Effective TCP/IP programming by Snader [addison wesley] But the R.Stevens books are definitely the way to go if starting out with C topics like you've describe above. GoodLuck. J. - To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2007-11-02 18:28 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2007-10-23 10:44 Creating a routing program - the basics Mateus Interciso 2007-10-23 11:15 ` Steve Graegert 2007-10-23 12:11 ` Mateus Interciso 2007-10-23 13:56 ` Steve Graegert 2007-10-23 14:13 ` Mateus Interciso 2007-11-02 18:28 ` J.
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