On Tue, 14 Jan 1997, Douglas Denny wrote:

Does anyone know about a Unix subnet calculator? It would be really really helpful.

Thanks

-Doug

/* ipmask.c * * Given argv[1] as a decimal netmask and argv[2] as a decimal IP address, * print the resulting broadcast and network addresses to stdout. This is * potentially useful in scripts which need the broadcast address and the * network address but want to ask the user as few questions as possible. * * Copyright 1994 by David Niemi. Written in about 30 minutes on 13 Aug. * The author places no restrictions on the use of this program, provided * that this copyright is preserved in any derived source code. * * Typical compilation command for Linux: * cc ipmask.c -Wall -O -m486 -N -o ipmask -s */ #define MYNAME "ipmask" #include <stdio.h> void Usage(void) { fprintf (stderr, "USAGE: %s <decimal netmask> <decimal IP address>\n", MYNAME); } int main(int argc, char *argv[]) { unsigned long netmask, ipaddr, netaddr, broadcast; int in[4], j; unsigned char bc[4],na[4]; if (3 != argc) { Usage(); exit(1); } /* Check netmask */ if (4 != sscanf(argv[1],"%d.%d.%d.%d", &in[0],&in[1],&in[2],&in[3])) { fprintf (stderr,"Invalid netmask \"%s\".\n", argv[1]); Usage(); exit(1); } for (j=0; j<4; ++j) { if (in[j]<0 || in[j]>255) { fprintf (stderr, "Invalid octet %d in netmask \"%s\".\n", j+1, argv[1]); Usage(); exit(1); } } netmask = in[3] + 256 * (in[2] + 256 * (in[1] + 256 * in[0])); /* Check IP address */ if (4 != sscanf(argv[2],"%d.%d.%d.%d", &in[0],&in[1],&in[2],&in[3])) { fprintf (stderr,"Invalid IP address \"%s\".\n", argv[2]); Usage(); exit(1); } for (j=0; j<4; ++j) { if (in[j]<0 || in[j]>255) { fprintf (stderr, "Invalid octet %d in IP address \"%s\".\n", j+1, argv[1]); Usage(); exit(1); } } ipaddr = in[3] + 256 * (in[2] + 256 * (in[1] + 256 * in[0])); broadcast = ipaddr | (~ netmask); bc[0] = broadcast / 256 / 256 / 256; bc[1] = (broadcast / 256 / 256) % 256; bc[2] = (broadcast / 256) % 256; bc[3] = broadcast % 256; netaddr = ipaddr & netmask; na[0] = netaddr / 256 / 256 / 256; na[1] = (netaddr / 256 / 256) % 256; na[2] = (netaddr / 256) % 256; na[3] = netaddr % 256; printf ("%d.%d.%d.%d %d.%d.%d.%d\n", bc[0], bc[1], bc[2], bc[3], na[0], na[1], na[2], na[3]); exit(0); } [-] Brett L. Hawn (blh @ nol dot net) [-] [-] Networks On-Line - Houston, Texas [-] [-] 713-467-7100 [-]