Re: Debugging network problems

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Some more info:

One of my major issues is during svn operations. In the middle of an
operation such svn up, the update starts ok, then at some point, I can
no longer connect to my server.

Each time, it stops at a different file, so that also doesn't tell me
anything about packet sizes or whatever, since I am unable to see any
pattern in all of this.


Any ideas would be greatly appreciated before I lose the little hair I
have left.

:-)




On Fri, 2007-08-31 at 16:43 +0900, David Leangen wrote:
> Thank you, Martijn,
> 
> My reply inline.
> 
> 
> > > Generally, I can connect to the outside world, and the outside world can
> > > connect to me. By this, I mean that each of the local machines behind my
> > > proxy can connect.
> > >
> > > However, the connections back to my own URL are sporadic. In other
> > > words, sometimes I can connect, sometimes I can't. Assuming my domain is
> > > my.company.com, when I try to connect to my.company.com from within my
> > > network, sometimes I can, sometimes I can't, but I have not at all
> > > figured out a pattern.
> > >
> > > When this happens, domain names are being resolved, but I get
> > > "Connection timed out" errors.
> > >
> 
> > Sounds like an PMTUD issue. Do you allow all ESTABLISHED packets in, not 
> > just tcp?
> 
> Yes, I'm letting all packets in:
> 
>   -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
> 
> 
> This is my iptables file (below).
> 
> Maybe somebody can spot the problem?
> 
> 
> Cheers,
> David
> 
> 
> 
> *mangle
> :PREROUTING ACCEPT [0:0]
> :INPUT ACCEPT [0:0]
> :FORWARD ACCEPT [0:0]
> :OUTPUT ACCEPT [0:0]
> :POSTROUTING ACCEPT [0:0]
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG
> FIN,PSH,URG -j DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j
> DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags SYN,RST SYN,RST -j DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG
> FIN,PSH,URG -j DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j
> DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags SYN,RST SYN,RST -j DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG
> FIN,PSH,URG -j DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j
> DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags SYN,RST SYN,RST -j DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG
> FIN,PSH,URG -j DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j
> DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags SYN,RST SYN,RST -j DROP
> -A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
> COMMIT
> 
> *nat
> :PREROUTING ACCEPT [0:0]
> :POSTROUTING ACCEPT [0:0]
> :OUTPUT ACCEPT [0:0]
> -A PREROUTING -p tcp --dport 5433 -j DNAT --to 192.168.2.10:5432
> -A PREROUTING -p udp --dport 5433 -j DNAT --to 192.168.2.10:5432
> -A PREROUTING -p tcp --dport 5434 -j DNAT --to 192.168.2.11:5432
> -A PREROUTING -p udp --dport 5434 -j DNAT --to 192.168.2.11:5432
> -A POSTROUTING -d 192.168.2.10 -s 192.168.0.0/255.255.0.0 -p tcp -j SNAT
> --to 192.168.11.100
> -A PREROUTING -p tcp -s 202.238.89.88 --dport 50000:50100 -j DNAT --to
> 192.168.2.5
> -A POSTROUTING -o eth0 -j MASQUERADE
> 
> COMMIT
> *filter
> :INPUT DROP [0:0]
> :FORWARD ACCEPT [0:0]
> :OUTPUT ACCEPT [0:0]
> :BLACKLIST - [0:0]
> :LOG_ACCEPT - [0:0]
> :LOG_DROP - [0:0]
> :icmp_packets - [0:0]
> -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 20 -j LOG_ACCEPT
> -A INPUT -p tcp -m tcp --dport 21 -j LOG_ACCEPT
> -A INPUT -p tcp -m tcp --dport 22 -j LOG_ACCEPT
> -A INPUT -p tcp -m tcp --dport 25 -j LOG_ACCEPT
> -A INPUT -p udp -m udp --dport 53 -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 110 -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 143 -j ACCEPT
> -A INPUT -p tcp -m tcp --dport 443 -j LOG_ACCEPT
> -A INPUT -p tcp -m tcp --dport 993 -j ACCEPT
> -A INPUT -p udp -m udp -s 192.168.0.0/255.255.0.0 --dport 10080 -j
> ACCEPT
> # The following line is for FTP passive ports
> -A INPUT -p tcp -m tcp --dport 55000:55500 -j LOG_ACCEPT
> -A INPUT -s 127.0.0.1 -j ACCEPT
> -A INPUT -p icmp -j icmp_packets
> -A INPUT -j LOG_DROP
> -A OUTPUT -p tcp -m tcp --dport 50000:50100 -j LOG_ACCEPT
> -A OUTPUT -p udp -m udp --dport 700:710 -j LOG_ACCEPT
> -A BLACKLIST -j LOG_DROP
> -A LOG_ACCEPT -j LOG --log-prefix "[IPTABLES ACCEPT] : "
> --log-tcp-options --log-ip-options
> -A LOG_ACCEPT -j ACCEPT
> -A LOG_DROP -j LOG --log-prefix "[IPTABLES DROP] : " --log-tcp-options
> --log-ip-options
> -A LOG_DROP -j DROP
> -A icmp_packets -p icmp -m icmp --icmp-type 0 -j ACCEPT
> -A icmp_packets -s 192.168.0.0/255.255.255.0 -p icmp -m icmp --icmp-type
> 8 -j ACCEPT
> -A icmp_packets -s 192.168.1.0/255.255.255.0 -p icmp -m icmp --icmp-type
> 8 -j ACCEPT
> -A icmp_packets -s 192.168.2.0/255.255.255.0 -p icmp -m icmp --icmp-type
> 8 -j ACCEPT
> -A icmp_packets -p icmp -m icmp --icmp-type 8 -j ACCEPT
> -A icmp_packets -p icmp -m icmp --icmp-type 3 -j ACCEPT
> -A icmp_packets -p icmp -m icmp --icmp-type 11 -j ACCEPT
> COMMIT
> 
> 
> 



[Index of Archives]     [Linux Netfilter Development]     [Linux Kernel Networking Development]     [Netem]     [Berkeley Packet Filter]     [Linux Kernel Development]     [Advanced Routing & Traffice Control]     [Bugtraq]

  Powered by Linux