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Diffstat (limited to 'usr.sbin/traceroute/README')
| -rw-r--r-- | usr.sbin/traceroute/README | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/usr.sbin/traceroute/README b/usr.sbin/traceroute/README new file mode 100644 index 0000000..6d33c6c --- /dev/null +++ b/usr.sbin/traceroute/README @@ -0,0 +1,126 @@ +Tue Dec 27 06:24:24 PST 1988 + +Traceroute is a system administrators utility to trace the route +ip packets from the current system take in getting to some +destination system. See the comments at the front of the +program for a description of its use. + +This program + + a) can only be run by root (it uses raw ip sockets). + + b) REQUIRES A KERNEL MOD to the raw ip output code to run. + +If you want to hack on your kernel, my modified version of the +routine rip_output (in file /sys/netinet/raw_ip.c) is attached. +This code may or may not resemble the code in your kernel. +It may offer you a place to start but I make no promises. +If you do hack your kernel, remember to test everything that uses +raw ip sockets (e.g., ping and egpup/gated) & make sure they still +work. I wish you the best of luck and you're on your own. + +If your system has the ttl bug mentioned in the source, you +might want to fix it while you're in the kernel. (This bug +appears in all releases of BSD up to but not including 4.3tahoe. +If your version of netinet/ip_icmp.c is any earlier than 7.3 +(April, '87), it has the bug.) The fix is just to add the line + ip->ip_ttl = MAXTTL; +after the line + ip->ip_src = t; +(or anywhere before the call to icmp_send) in routine icmp_reflect. + +If you're running this on a pre-4.3bsd system (e.g., Sun 3.x, +Ultrix) that strips ip headers from icmp messages, add -DARCHAIC +to CFLAGS in the Makefile. Also note that rip_output contains +a conditional for a 4.2/4.3 change in the location of a raw +socket's protocol number. I've checked this under 4.3 & Sun OS +3.5 but you should double-check your system to make sure the +appropriate branch of the #if is taken (check the line that +assigned to ip->ip_p in your system's original rip_output). + +A couple of awk programs to massage the traceroute output are +included. "mean.awk" and "median.awk" compute the mean and median +time to each hop, respectively. I've found that something like + + traceroute -q 7 foo.somewhere >t + awk -f median.awk t | graph + +can give you a quick picture of the bad spots on a long +path (median is usually a better noise filter than mean). + +Enjoy. + + - Van Jacobson (van@helios.ee.lbl.gov) + +-------------------- rip_output from /sys/netinet/raw_ip.c +rip_output(m, so) + register struct mbuf *m; + struct socket *so; +{ + register struct ip *ip; + int error; + struct rawcb *rp = sotorawcb(so); + struct sockaddr_in *sin; +#if BSD>=43 + short proto = rp->rcb_proto.sp_protocol; +#else + short proto = so->so_proto->pr_protocol; +#endif + /* + * if the protocol is IPPROTO_RAW, the user handed us a + * complete IP packet. Otherwise, allocate an mbuf for a + * header and fill it in as needed. + */ + if (proto != IPPROTO_RAW) { + /* + * Calculate data length and get an mbuf + * for IP header. + */ + int len = 0; + struct mbuf *m0; + + for (m0 = m; m; m = m->m_next) + len += m->m_len; + + m = m_get(M_DONTWAIT, MT_HEADER); + if (m == 0) { + m = m0; + error = ENOBUFS; + goto bad; + } + m->m_off = MMAXOFF - sizeof(struct ip); + m->m_len = sizeof(struct ip); + m->m_next = m0; + + ip = mtod(m, struct ip *); + ip->ip_tos = 0; + ip->ip_off = 0; + ip->ip_p = proto; + ip->ip_len = sizeof(struct ip) + len; + ip->ip_ttl = MAXTTL; + } else + ip = mtod(m, struct ip *); + + if (rp->rcb_flags & RAW_LADDR) { + sin = (struct sockaddr_in *)&rp->rcb_laddr; + if (sin->sin_family != AF_INET) { + error = EAFNOSUPPORT; + goto bad; + } + ip->ip_src.s_addr = sin->sin_addr.s_addr; + } else + ip->ip_src.s_addr = 0; + + ip->ip_dst = ((struct sockaddr_in *)&rp->rcb_faddr)->sin_addr; + +#if BSD>=43 + return (ip_output(m, rp->rcb_options, &rp->rcb_route, + (so->so_options & SO_DONTROUTE) | IP_ALLOWBROADCAST)); +#else + return (ip_output(m, (struct mbuf *)0, &rp->rcb_route, + (so->so_options & SO_DONTROUTE) | IP_ALLOWBROADCAST)); +#endif +bad: + m_freem(m); + return (error); +} |
