traceroute
in [Slackware]
|
From: root on 1 Jun 2010 18:45 FYI: Sometime, a long time ago, my traceroute stopped working. I only got * for every step. Recently I found a need for traceroute and looked online to find a fix. I found suggestions, but no fix. After a little experimenting I find that traceroute works as before if you use the -I option. You can alias traceroute to "traceroute -I"
From: Lew Pitcher on 1 Jun 2010 19:01 On June 1, 2010 18:45, in alt.os.linux.slackware, NoEMail(a)home.org wrote: > FYI: > Sometime, a long time ago, my traceroute > stopped working. I only got * for every > step. Recently I found a need for traceroute > and looked online to find a fix. I found > suggestions, but no fix. After a little > experimenting I find that traceroute > works as before if you use the -I option. "Classic" traceroute sends UDP packets with ascending TTL values to high-end (and presumably unused) ports on the target system. As each TTL expires, the expiry point sends back an ICMP time-exceeded packet (ICMP type 5, code 0), which includes the expiry point's IP address. This is the default for the traceroute included in Slackware. Other implementations of traceroute use the ICMP "ECHO REQUEST" packet (ICMP type 8, code 0), again with ascending TTL values, and get back ICMP time-exceeded packets when each TTL expires. This is the behaviour of Slackware's traceroute, with the -I option. Historically, traceroute used UDP packets ("classic" traceroute) because /some/ routers would *not* return ICMP error packets to ICMP messages. Had "classic" traceroute used ICMP "ECHO REQUEST" messages, these routers would silently discard the expired message, leaving a TTL unaccounted for. Hopefully, those sorts of router have disappeared. These days, the "classic" traceroute might not work because of firewalling. Typically, firewalls block some (or all) UDP traffic, causing the "classic" traceroute's UDP packets to be silently discarded. OTOH, there's no guarantee that the ICMP "ECHO REQUEST" traceroute will fare any better. Those same firewalls can (and often do) drop some ICMP messages. Those firewalls practice a sort of "security by obscurity" by preventing outsiders from "pinging" addresses inside the firewall. > You can alias traceroute to "traceroute -I" HTH -- Lew Pitcher Master Codewright & JOAT-in-training | Registered Linux User #112576 Me: http://pitcher.digitalfreehold.ca/ | Just Linux: http://justlinux.ca/ ---------- Slackware - Because I know what I'm doing. ------
From: root on 1 Jun 2010 19:23 Lew Pitcher <lpitcher(a)teksavvy.com> wrote: > > These days, the "classic" traceroute might not work because of firewalling. > Typically, firewalls block some (or all) UDP traffic, causing the "classic" > traceroute's UDP packets to be silently discarded. > > OTOH, there's no guarantee that the ICMP "ECHO REQUEST" traceroute will fare > any better. Those same firewalls can (and often do) drop some ICMP > messages. Those firewalls practice a sort of "security by obscurity" by > preventing outsiders from "pinging" addresses inside the firewall. > >> You can alias traceroute to "traceroute -I" > > HTH Thanks for responding. I turned off all firewalling in attempts to get traceroute to work: no luck. At least for the time being I am happy with this fix.
From: Mike Spencer on 1 Jun 2010 22:59 It's also possible that misconfiguration at your ISP can block traceroute. This happened to me at one point. I would have been stumped had it not been the case that my ISP had two portal machines (I forget the technical term) for dialup and traceroute worked when my connection went through one but not with the other. Because I was able to point to this discrepancy, the ISP support guy fixed things up. I have no idea what specific config detail(s) caused this. -- Mike Spencer Nova Scotia, Canada
From: Mikhail Zotov on 2 Jun 2010 02:00 On Tue, 1 Jun 2010 22:45:13 +0000 (UTC) root <NoEMail(a)home.org> wrote: > FYI: > Sometime, a long time ago, my traceroute > stopped working. I only got * for every > step. Recently I found a need for traceroute > and looked online to find a fix. I found > suggestions, but no fix. After a little > experimenting I find that traceroute > works as before if you use the -I option. > You can alias traceroute to "traceroute -I" Sometimes, tcptraceroute can be a more convenient tool. -- Mikhail
|
Next
|
Last
Pages: 1 2 Prev: Broken KDE 3.3 Advanced Text Editor "kate" Next: info about slackware project |