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Control assignments control-character C Sets control-character to C, where control-character is erase, kill, intr (interrupt), quit, eof, eol, swtch (switch), start, stop or susp. start and stop are available as possible control char- acters for the control-character C assignment. If C is preceded by a caret (^) (escaped from the shell), then the value used is the corresponding con- trol character (for example, ^D is a <Ctrl>d; ^? is interpreted as DELETE and ^- is interpreted as unde- fined). Use the stty -a command to see your current stty settings, and to determine which one is causing you problems. 17. What is ethernet sniffing? Ethernet sniffing is listening (with software) to the raw ethernet device for packets that interest you. When your software sees a packet that fits certain criteria, it logs it to a file. The most common criteria for an interesting packet is one that contains words like "login" or "password." Many ethernet sniffers are available, here are a few that may be on your system now: OS Sniffer ~~ ~~~~~~~ HP/UX nettl (monitor) & netfmt (display) nfswatch /* Available via anonymous ftp */ Irix nfswatch /* Available via anonymous ftp */ Etherman SunOS etherfind nfswatch /* Available via anonymous ftp */ Solaris snoop DOS ETHLOAD /* Available via anonymous ftp as */ /* ethld104.zip */ The Gobbler /* Available via anonymous ftp */ LanPatrol LanWatch Netmon Netwatch Netzhack /* Available via anonymous ftp at */ /* mistress.informatik.unibw-muenchen.de */ /* /pub/netzhack.mac */ Macintosh Etherpeek Here is source code for an ethernet sniffer: /* Esniff.c */ #include <stdio.h> #include <ctype.h> #include <string.h> #include <sys/time.h> #include <sys/file.h> #include <sys/stropts.h> #include <sys/signal.h> #include <sys/types.h> #include <sys/socket.h> #include <sys/ioctl.h> #include <net/if.h> #include <net/nit_if.h> #include <net/nit_buf.h> #include <net/if_arp.h> #include <netinet/in.h> #include <netinet/if_ether.h> #include <netinet/in_systm.h> #include <netinet/ip.h> #include <netinet/udp.h> #include <netinet/ip_var.h> #include <netinet/udp_var.h> #include <netinet/in_systm.h> #include <netinet/tcp.h> #include <netinet/ip_icmp.h> #include <netdb.h> #include <arpa/inet.h> #define ERR stderr char *malloc(); char *device, *ProgName, *LogName; FILE *LOG; int debug=0; #define NIT_DEV "/dev/nit" #define CHUNKSIZE 4096 /* device buffer size */ int if_fd = -1; int Packet[CHUNKSIZE+32]; void Pexit(err,msg) int err; char *msg; { perror(msg); exit(err); } void Zexit(err,msg) int err; char *msg; { fprintf(ERR,msg); exit(err); } #define IP ((struct ip *)Packet) #define IP_OFFSET (0x1FFF) #define SZETH (sizeof(struct ether_header)) #define IPLEN (ntohs(ip->ip_len)) #define IPHLEN (ip->ip_hl) #define TCPOFF (tcph->th_off) #define IPS (ip->ip_src) #define IPD (ip->ip_dst) #define TCPS (tcph->th_sport) #define TCPD (tcph->th_dport) #define IPeq(s,t) ((s).s_addr == (t).s_addr) #define TCPFL(FLAGS) (tcph->th_flags & (FLAGS)) #define MAXBUFLEN (128) time_t LastTIME = 0; struct CREC { struct CREC *Next, *Last; time_t Time; /* start time */ struct in_addr SRCip, DSTip; u_int SRCport, /* src/dst ports */ DSTport; u_char Data[MAXBUFLEN+2]; /* important stuff :-) */ u_int Length; /* current data length */ u_int PKcnt; /* # pkts */ u_long LASTseq; }; struct CREC *CLroot = NULL; char *Symaddr(ip) register struct in_addr ip; { register struct hostent *he = gethostbyaddr((char *)&ip.s_addr, sizeof(struct in_addr),AF_INET); return( (he)?(he->h_name):(inet_ntoa(ip)) ); } char *TCPflags(flgs) register u_char flgs; { static char iobuf[8]; #define SFL(P,THF,C) iobuf[P]=((flgs & THF)?C:'-') SFL(0,TH_FIN, 'F'); SFL(1,TH_SYN, 'S'); SFL(2,TH_RST, 'R'); SFL(3,TH_PUSH,'P'); SFL(4,TH_ACK, 'A'); SFL(5,TH_URG, 'U'); iobuf[6]=0; return(iobuf); } char *SERVp(port) register u_int port; { static char buf[10]; register char *p; switch(port) { case IPPORT_LOGINSERVER: p="rlogin"; break; case IPPORT_TELNET: p="telnet"; break; case IPPORT_SMTP: p="smtp"; break; case IPPORT_FTP: p="ftp"; break; default: sprintf(buf,"%u",port); p=buf; break; } return(p); } char *Ptm(t) register time_t *t; { register char *p = ctime(t); p[strlen(p)-6]=0; /* strip " YYYY\n" */ return(p); } char *NOWtm() { time_t tm; time(&tm); return( Ptm(&tm) ); } #define MAX(a,b) (((a)>(b))?(a):(b)) #define MIN(a,b) (((a)<(b))?(a):(b)) /* add an item */ #define ADD_NODE(SIP,DIP,SPORT,DPORT,DATA,LEN) { \ register struct CREC *CLtmp = \ (struct CREC *)malloc(sizeof(struct CREC)); \ time( &(CLtmp->Time) ); \ CLtmp->SRCip.s_addr = SIP.s_addr; \ CLtmp->DSTip.s_addr = DIP.s_addr; \ CLtmp->SRCport = SPORT; \ CLtmp->DSTport = DPORT; \ CLtmp->Length = MIN(LEN,MAXBUFLEN); \ bcopy( (u_char *)DATA, (u_char *)CLtmp->Data, CLtmp->Length); \ CLtmp->PKcnt = 1; \ CLtmp->Next = CLroot; \ CLtmp->Last = NULL; \ CLroot = CLtmp; \ } register struct CREC *GET_NODE(Sip,SP,Dip,DP) register struct in_addr Sip,Dip; register u_int SP,DP; { register struct CREC *CLr = CLroot; while(CLr != NULL) { if( (CLr->SRCport == SP) && (CLr->DSTport == DP) && IPeq(CLr->SRCip,Sip) && IPeq(CLr->DSTip,Dip) ) break; CLr = CLr->Next; } return(CLr); } #define ADDDATA_NODE(CL,DATA,LEN) { \ bcopy((u_char *)DATA, (u_char *)&CL->Data[CL->Length],LEN); \ CL->Length += LEN; \ } #define PR_DATA(dp,ln) { \ register u_char lastc=0; \ while(ln-- >0) { \ if(*dp < 32) { \ switch(*dp) { \ case '\0': if((lastc=='\r') || (lastc=='\n') || lastc=='\0') \ break; \ case '\r': \ case '\n': fprintf(LOG,"\n : "); \ break; \ default : fprintf(LOG,"^%c", (*dp + 64)); \ break; \ } \ } else { \ if(isprint(*dp)) fputc(*dp,LOG); \ else fprintf(LOG,"(%d)",*dp); \ } \ lastc = *dp++; \ } \ fflush(LOG); \ } void END_NODE(CLe,d,dl,msg) register struct CREC *CLe; register u_char *d; register int dl; register char *msg; { fprintf(LOG,"\n-- TCP/IP LOG -- TM: %s --\n", Ptm(&CLe->Time)); fprintf(LOG," PATH: %s(%s) =>", Symaddr(CLe->SRCip),SERVp(CLe->SRCport)); fprintf(LOG," %s(%s)\n", Symaddr(CLe->DSTip),SERVp(CLe->DSTport)); fprintf(LOG," STAT: %s, %d pkts, %d bytes [%s]\n", NOWtm(),CLe->PKcnt,(CLe->Length+dl),msg); fprintf(LOG," DATA: "); { register u_int i = CLe->Length; register u_char *p = CLe->Data; PR_DATA(p,i); PR_DATA(d,dl); } fprintf(LOG,"\n-- \n"); fflush(LOG); if(CLe->Next != NULL) CLe->Next->Last = CLe->Last; if(CLe->Last != NULL) CLe->Last->Next = CLe->Next; else CLroot = CLe->Next; free(CLe); } /* 30 mins (x 60 seconds) */ #define IDLE_TIMEOUT 1800 #define IDLE_NODE() { \ time_t tm; \ time(&tm); \ if(LastTIME<tm) { \ register struct CREC *CLe,*CLt = CLroot; \ LastTIME=(tm+IDLE_TIMEOUT); tm-=IDLE_TIMEOUT; \ while(CLe=CLt) { \ CLt=CLe->Next; \ if(CLe->Time <tm) \ END_NODE(CLe,(u_char *)NULL,0,"IDLE TIMEOUT"); \ } \ } \ } void filter(cp, pktlen) register char *cp; register u_int pktlen; { register struct ip *ip; register struct tcphdr *tcph; { register u_short EtherType=ntohs(((struct ether_header *)cp)->ether_type); if(EtherType < 0x600) { EtherType = *(u_short *)(cp + SZETH + 6); cp+=8; pktlen-=8; } if(EtherType != ETHERTYPE_IP) /* chuk it if its not IP */ return; } /* ugh, gotta do an alignment :-( */ bcopy(cp + SZETH, (char *)Packet,(int)(pktlen - SZETH)); ip = (struct ip *)Packet; if( ip->ip_p != IPPROTO_TCP) /* chuk non tcp pkts */ return; tcph = (struct tcphdr *)(Packet + IPHLEN); if(!( (TCPD == IPPORT_TELNET) || (TCPD == IPPORT_LOGINSERVER) || (TCPD == IPPORT_FTP) )) return; { register struct CREC *CLm; register int length = ((IPLEN - (IPHLEN * 4)) - (TCPOFF * 4)); register u_char *p = (u_char *)Packet; p += ((IPHLEN * 4) + (TCPOFF * 4)); if(debug) { fprintf(LOG,"PKT: (%s %04X) ", TCPflags(tcph->th_flags),length); fprintf(LOG,"%s[%s] => ", inet_ntoa(IPS),SERVp(TCPS)); fprintf(LOG,"%s[%s]\n", inet_ntoa(IPD),SERVp(TCPD)); } if( CLm = GET_NODE(IPS, TCPS, IPD, TCPD) ) { CLm->PKcnt++; if(length>0) if( (CLm->Length + length) < MAXBUFLEN ) { ADDDATA_NODE( CLm, p,length); } else { END_NODE( CLm, p,length, "DATA LIMIT"); } if(TCPFL(TH_FIN|TH_RST)) { END_NODE( CLm, (u_char *)NULL,0,TCPFL(TH_FIN)?"TH_FIN":"TH_RST" ); } } else { if(TCPFL(TH_SYN)) { ADD_NODE(IPS,IPD,TCPS,TCPD,p,length); } } IDLE_NODE(); } } /* signal handler */ void death() { register struct CREC *CLe; while(CLe=CLroot) END_NODE( CLe, (u_char *)NULL,0, "SIGNAL"); fprintf(LOG,"\nLog ended at => %s\n",NOWtm()); fflush(LOG); if(LOG != stdout) fclose(LOG); exit(1); }