[clue-tech] intermittent connection failures

[Jason S. Friedman]

Very odd behavior.

I cannot reach certain websites, such as microsoft.com, marc.info, 
kristian.vilmann.net.  The browser times out.

Ping registers different times for different hosts:
jason at goldenrule:~> ping -c 5 www.qwest.com
PING www.qwest.com (155.70.40.252) 56(84) bytes of data.
64 bytes from 155.70.40.252: icmp_seq=1 ttl=118 time=34.4 ms
64 bytes from 155.70.40.252: icmp_seq=2 ttl=118 time=33.9 ms
64 bytes from 155.70.40.252: icmp_seq=3 ttl=118 time=33.6 ms
64 bytes from 155.70.40.252: icmp_seq=4 ttl=118 time=34.1 ms
64 bytes from 155.70.40.252: icmp_seq=5 ttl=118 time=33.5 ms

--- www.qwest.com ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 20156ms
rtt min/avg/max/mdev = 33.557/33.965/34.487/0.396 ms

jason at goldenrule:~> ping -c 5 www.qwest.net
PING www.qwest.net (204.147.80.81) 56(84) bytes of data.
64 bytes from www.qwest.net (204.147.80.81): icmp_seq=1 ttl=247 time=58.8 ms
64 bytes from uswest.net (204.147.80.81): icmp_seq=2 ttl=247 time=58.6 ms
64 bytes from wwwld.uswest.net (204.147.80.81): icmp_seq=3 ttl=247 
time=58.5 ms
64 bytes from www.uswest.net (204.147.80.81): icmp_seq=4 ttl=247 
time=58.9 ms
64 bytes from www.qwest.net (204.147.80.81): icmp_seq=5 ttl=247 time=58.8 ms

--- www.qwest.net ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4007ms
rtt min/avg/max/mdev = 58.598/58.790/58.947/0.251 ms

My mail server fails to receive mail from comcast.net, among a few others:
root at goldenrule /var/log $ grep 'timeout after DATA' mail.log | cut 
-f6-99 -d" " | sort | uniq
timeout after DATA (0 bytes) from mta.emails.meredith.com[198.31.62.42]
timeout after DATA (0 bytes) from 
outbd-pstfx.customercenter.net[208.235.248.20]
timeout after DATA (0 bytes) from outbound3.bullhorn.com[209.202.131.98]
timeout after DATA (0 bytes) from 
strongmail6.yorksolutions.net[209.252.82.246]
timeout after DATA (0 bytes) from unknown[218.248.67.247]
timeout after DATA (0 bytes) from unknown[222.252.213.178]
timeout after DATA (0 bytes) from unknown[41.205.230.39]
timeout after DATA (1011 bytes) from outbound.wom.com[216.58.169.194]
timeout after DATA (1022 bytes) from outbound.wom.com[216.58.169.194]
timeout after DATA (187 bytes) from 
qmta05.emeryville.ca.mail.comcast.net[76.96.30.48]
timeout after DATA (187 bytes) from 
qmta12.emeryville.ca.mail.comcast.net[76.96.27.227]
timeout after DATA (189 bytes) from 
qmta06.westchester.pa.mail.comcast.net[76.96.62.56]
timeout after DATA (189 bytes) from 
qmta08.westchester.pa.mail.comcast.net[76.96.62.80]
timeout after DATA (189 bytes) from 
qmta11.westchester.pa.mail.comcast.net[76.96.59.211]
timeout after DATA (856 bytes) from mail.vsym.com[38.119.104.98]

but can receive from most (~600 others):
root at goldenrule /var/log $ grep ' connect from' mail.log | grep -v 
unknown | cut -f6-99 -d" " | sort | uniq | wc -l
611

My mail server can _send_ to comcast.net.

Qwest is my DSL provider.  My download speed seems to vary between 2.5 
and 7.5 Mb/s.