Skip to main content

MAC for specific Adapter on Linux


Today was working on getting a unique information for a system. And MAC would be enough for my requirement. (Need not go for a UID). Below is the code to find MAC for a specific Adapter. "eth0" for my case.
Only different thing here is the structure ifreq which I used for the first time.




Here is the struct information.
struct ifreq {
    char    ifr_name[IFNAMSIZ];/* Interface name */
    union {
            struct sockaddr ifr_addr;
            struct sockaddr ifr_dstaddr;
            struct sockaddr ifr_broadaddr;
            struct sockaddr ifr_netmask;
            struct sockaddr ifr_hwaddr;
            short   ifr_flags;
            int     ifr_ifindex;
            int     ifr_metric;
            int     ifr_mtu;
            struct ifmapifr_map;
            char    ifr_slave[IFNAMSIZ];
            char    ifr_newname[IFNAMSIZ];
            char *  ifr_data;
    };
};
struct ifconf { 
    int ifc_len;    /* size of buffer */
    union {            
            char *  ifc_buf; /* buffer address */ 
            struct ifreq *ifc_req; /* array of structures */
    };  
};

You can more information about this structure here below. 




#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/if.h>
int main()
{
    int socketDescriptor;
    struct ifreq mac_info;
    /*UDP Socket created here*/
    socketDescriptor = socket(AF_INET, SOCK_DGRAM, 0);
    mac_info.ifr_addr.sa_family = AF_INET;

    /*Information for eth0*/
    strncpy(mac_info.ifr_name, "eth0", IFNAMSIZ-1);
    ioctl(socketDescriptor, SIOCGIFHWADDR, &mac_info);

    /*Closing Socket*/
    close(socketDescriptor);

    /*Lets Print this information*/
    printf("%.2x:%.2x:%.2x:%.2x:%.2x:%.2x\n",
         (unsigned char)mac_info.ifr_hwaddr.sa_data[0],
         (unsigned char)mac_info.ifr_hwaddr.sa_data[1],
         (unsigned char)mac_info.ifr_hwaddr.sa_data[2],
         (unsigned char)mac_info.ifr_hwaddr.sa_data[3],
         (unsigned char)mac_info.ifr_hwaddr.sa_data[4],
         (unsigned char)mac_info.ifr_hwaddr.sa_data[5]);
    return 0;
}

OUTPUT:
 
ahmed@ahmed-work-horse:~/rnd$ gcc testMac.c 
ahmed@ahmed-work-horse:~/rnd$ ./a.out 
00:12:64:12:7f:0a
ahmed@ahmed-work-horse:~/rnd$ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:12:64:12:7f:0a  
          inet addr:172.16.2.15  Bcast:172.16.2.255  Mask:255.255.255.0
          inet6 addr: fe80::225:64ff:fe82:7f0a/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:3158057 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2005005 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2865103780 (2.8 GB)  TX bytes:200486870 (200.4 MB)
          Interrupt:42 Base address:0x4000 
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:41143 errors:0 dropped:0 overruns:0 frame:0
          TX packets:41143 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:10216832 (10.2 MB)  TX bytes:10216832 (10.2 MB)
vmnet1    Link encap:Ethernet  HWaddr 00:50:12:c0:00:01  
          inet addr:172.16.45.1  Bcast:172.16.45.255  Mask:255.255.255.0
          inet6 addr: fe80::250:56ff:fec0:1/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1028 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
vmnet8    Link encap:Ethernet  HWaddr 00:50:12:c0:00:08  
          inet addr:172.16.167.1  Bcast:172.16.167.255  Mask:255.255.255.0
          inet6 addr: fe80::250:56ff:fec0:8/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1377 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1033 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
ahmed@ahmed-work-horse:~/rnd$
Labels:

Comments

Post a Comment

Popular posts from this blog

Cloudera Manager - Duplicate entry 'zookeeper' for key 'NAME'.

We had recently built a cluster using cloudera API’s and had all the services running on it with Kerberos enabled. Next we had a requirement to add another kafka cluster to our already exsisting cluster in cloudera manager. Since it is a quick task to get the zookeeper and kafka up and running. We decided to get this done using the cloudera manager instead of the API’s. But we faced the Duplicate entry 'zookeeper' for key 'NAME' issue as described in the bug below. https://issues.cloudera.org/browse/DISTRO-790 I have set up two clusters that share a Cloudera Manger. The first I set up with the API and created the services with capital letter names, e.g., ZOOKEEPER, HDFS, HIVE. Now, I add the second cluster using the Wizard. Add Cluster->Select Hosts->Distribute Parcels->Select base HDFS Cluster install On the next page i get SQL errros telling that the services i want to add already exist. I suspect that the check for existing service names does n
2 comments
Read more

Zabbix History Table Clean Up

Zabbix history table gets really big, and if you are in a situation where you want to clean it up. Then we can do so, using the below steps. Stop zabbix server. Take table backup - just in case. Create a temporary table. Update the temporary table with data required, upto a specific date using epoch . Move old table to a different table name. Move updated (new temporary) table to original table which needs to be cleaned-up. Drop the old table. (Optional) Restart Zabbix Since this is not offical procedure, but it has worked for me so use it at your own risk. Here is another post which will help is reducing the size of history tables - http://zabbixzone.com/zabbix/history-and-trends/ Zabbix Version : Zabbix v2.4 Make sure MySql 5.1 is set with InnoDB as innodb_file_per_table=ON Step 1 Stop the Zabbix server sudo service zabbix-server stop Script. echo "------------------------------------------" echo " 1. Stopping Zabbix Server &quo
1 comment
Read more

Access Filter in SSSD `ldap_access_filter` [SSSD Access denied / Permission denied ]

Access Filter Setup with SSSD ldap_access_filter (string) If using access_provider = ldap , this option is mandatory. It specifies an LDAP search filter criteria that must be met for the user to be granted access on this host. If access_provider = ldap and this option is not set, it will result in all users being denied access. Use access_provider = allow to change this default behaviour. Example: access_provider = ldap ldap_access_filter = memberOf=cn=allowed_user_groups,ou=Groups,dc=example,dc=com Prerequisites yum install sssd Single LDAP Group Under domain/default in /etc/sssd/sssd.conf add: access_provider = ldap ldap_access_filter = memberOf=cn=Group Name,ou=Groups,dc=example,dc=com Multiple LDAP Groups Under domain/default in /etc/sssd/sssd.conf add: access_provider = ldap ldap_access_filter = (|(memberOf=cn=System Adminstrators,ou=Groups,dc=example,dc=com)(memberOf=cn=Database Users,ou=Groups,dc=example,dc=com)) ldap_access_filter accepts standa
Post a Comment
Read more