+### Adverse communication.
+
+AT_SETUP([server retry])
+AT_KEYWORDS([backoff])
+export TRIPE_SLIPIF=USLIP
+
+for i in alice bob; do (mkdir $i; cd $i; SETUPDIR([beta])); done
+
+WITH_2TRIPES([alice], [bob], [-nslip], [-talice], [-tbob], [
+
+ ## Set up the evil proxy.
+ alicemitm=24516 bobmitm=14016
+ MITM -kalice/keyring.pub >mitm.out 2>mitm.err \
+ peer:alice:$alicemitm:127.0.0.1:$(cat alice/port) \
+ peer:bob:$bobmitm:127.0.0.1:$(cat bob/port) \
+ filt:drop:5 filt:send& mitmpid=$!
+ strace -omitm.trace -p$mitmpid& mitmtrace=$!
+ trap 'kill $mitmpid $mitmtrace; exit 127' EXIT INT QUIT TERM HUP
+
+ ## Try to establish keys anyway.
+ AWAIT_KXDONE([alice], [alice], [bob], [bob], [
+ AT_CHECK([TRIPECTL -dalice ADD -cork bob INET 127.0.0.1 $alicemitm])
+ AT_CHECK([TRIPECTL -dbob ADD alice INET 127.0.0.1 $bobmitm])
+ ])
+
+ ## Check pinging.
+ COMMS_EPING([alice], [alice], [bob], [bob], [10])
+ COMMS_EPING([bob], [bob], [alice], [alice], [10])
+
+ ## Tear down the MITM proxy.
+ kill $mitmpid
+ wait $mitmpid
+ wait $mitmtrace
+])
+
+AT_CLEANUP
+
+###--------------------------------------------------------------------------