Re: Long connection pauses?
On Sunday 08 January 2006 10:06 pm, Brian Chabot wrote: On Sunday 08 January 2006 09:37 pm, Bruce Dawson wrote: Ben Scott wrote: |On 1/8/06, Brian Chabot [EMAIL PROTECTED] wrote: |I have a relatively new machine that pauses for 20-120 seconds between |SYN/ACK and issuing the banner on all TCP connections. Typically, this is indicative of DNS resolution problems. Check your /etc/resolv.conf. I thought so, too. You still haven't said what service (or services) - that's the single most important detail here. That said, the first thing that occurs to me is that an ident daemon maybe should be running, or if you're behind a NAT or a router, identd packets are getting blocked. Lots of services will check this before establishing a connection, most notable mail, but that's usually on outgoing connections that it would cause issues. Again, without at least some details, not much to do but speculate. -N ___ gnhlug-discuss mailing list gnhlug-discuss@mail.gnhlug.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss
Long connection pauses?
I've been pulling my hair out trying to figure soething out. I have a relatively new machine that pauses for 20-120 seconds between SYN/ACK and issuing the banner on all TCP connections. This has been verified by several other systems connecting and using both windows and Linux. The machine is running Mandriva 2006, but so are three other machines on the network and none of them have this problem. All the xinetd settings are identical, as are resolv.conf. ps and top show nothing going on... just a pause of usually 20 seconds per tcp connection. Anyone know where I might look to find out what is causing this? TIA, Brian ___ gnhlug-discuss mailing list gnhlug-discuss@mail.gnhlug.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss
Re: Long connection pauses?
On 1/8/06, Brian Chabot [EMAIL PROTECTED] wrote: I have a relatively new machine that pauses for 20-120 seconds between SYN/ACK and issuing the banner on all TCP connections. Kevin's right in that you need to provide more information. Since TCP itself never issues a banner, you're clearly talking about some higher-level protocol(s) layered on top of TCP. What are they? Is the machine running a firewall? What happens if you shut it off? (You'll want to make sure the box is well secured before you do that.) Are you traversing a firewall, NAT boundary, load balancer, or some other smart device on your way to testing the connection? What happens if you start the connection beyond said device? Try shutting down all but a few services. For example, stop everything but syslog, network, and sshd, and then see if you can connect to sshd. The machine is running Mandriva 2006, but so are three other machines on the network and none of them have this problem. All the xinetd settings are identical, as are resolv.conf The difference must be somewhere else, then. :) Unless by identical you really mean mostly the same, which often later becomes mostly the same except for the one critical thing I overlooked. :) -- Ben ___ gnhlug-discuss mailing list gnhlug-discuss@mail.gnhlug.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss
Re: Long connection pauses?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Ben Scott wrote: |On 1/8/06, Brian Chabot [EMAIL PROTECTED] wrote: | |I have a relatively new machine that pauses for 20-120 seconds between |SYN/ACK and issuing the banner on all TCP connections. Typically, this is indicative of DNS resolution problems. Check your /etc/resolv.conf. | | Kevin's right in that you need to provide more information. | | Since TCP itself never issues a banner, you're clearly talking about |some higher-level protocol(s) layered on top of TCP. What are they? | | Is the machine running a firewall? What happens if you shut it off? | (You'll want to make sure the box is well secured before you do |that.) | | Are you traversing a firewall, NAT boundary, load balancer, or some |other smart device on your way to testing the connection? What |happens if you start the connection beyond said device? | | Try shutting down all but a few services. For example, stop |everything but syslog, network, and sshd, and then see if you can |connect to sshd. | |The machine is running Mandriva 2006, but so are three other machines on |the network and none of them have this problem. All the xinetd settings |are identical, as are resolv.conf | | | The difference must be somewhere else, then. :) | | Unless by identical you really mean mostly the same, which often |later becomes mostly the same except for the one critical thing I |overlooked. :) -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.1 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFDwcxw/TBScWXa5IgRAp6aAJ0UGtuN0BnDoThu1gDoGnjdESOeawCaA74b TBWGZOKHKY7uAMx3w9U6+NM= =W+bv -END PGP SIGNATURE- ___ gnhlug-discuss mailing list gnhlug-discuss@mail.gnhlug.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss
Re: Long connection pauses?
On Sunday 08 January 2006 09:37 pm, Bruce Dawson wrote: Ben Scott wrote: |On 1/8/06, Brian Chabot [EMAIL PROTECTED] wrote: |I have a relatively new machine that pauses for 20-120 seconds between |SYN/ACK and issuing the banner on all TCP connections. Typically, this is indicative of DNS resolution problems. Check your /etc/resolv.conf. I thought so, too. But the resolv.conf is functionally identical to those in the other Mandriva installs on the same LAN. (only the comments were different.) Nameservers are pingable, fast, and name resolution works. The pause continues on machines where this ons can get a PTR in miliseconds. I'll shut off some services and get a tcpdump tomorrow night. This box was forced into early production after a HDD failure just before Christmas. Previous testing with ethereal shows no packets between ACK and the service's banner many seconds later. Brian ___ gnhlug-discuss mailing list gnhlug-discuss@mail.gnhlug.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss
